Histiocytic sarcoma following CAR T-cell therapy: a case report

BACKGROUND

Development of secondary tumor after CART treatment is not well investigated. We report a pediatric B-cell acute lymphoblastic leukemia (B-ALL) patient who developed histiocytic sarcoma shortly after CART therapy.

CASE REPORT

A 9-year-old boy diagnosed with relapsed B-ALL presenting the KRAS A146T mutation received autologous mouse-derived CD19 and CD22 chimeric antigen receptor T-cell therapy at our center (Chinese Clinical Trial Registry: ChiCTR2000032211). Thirty days post-CART therapy, the bone marrow showed complete remission. At 85 days post-CART therapy, the boy presented with fever and chills. An abdominal CT scan showed massive hepatomegaly with multiple low-density lesions in the liver. At 130 days post-CART therapy, a bone marrow smear showed abnormal proliferation of macrophages, some of which exhibited phagocytosis. On day 136 post-CART therapy, laparoscopic liver biopsy was performed, revealing multiple yellow-white lesions on the surface of the liver. Microscopically, multifocal lesions were observed, predominantly composed of cells with abundant cytoplasm. Immunohistochemical staining indicated histiocytic origin. Based on the immunohistochemical results, histiocytic sarcoma was diagnosed. The same cytogenetic markers were identified in histiocytic sarcoma.

CONCLUSION

Our case illustrates a rare complication after CART therapy. The diagnosis and treatment of histiocytic sarcoma pose many challenges.

Histiocytic sarcoma mimicking localized tenosynovial giant cell tumor in the pediatric foot: A rare case report with MRI Findings

We present a rare case of histiocytic sarcoma (HS) occurring in the foot of a 12-year-old male, initially misdiagnosed as localized tenosynovial giant cell tumor (TSGCT). HS is an exceptionally uncommon hematologic malignant neoplasm, with its occurrence in children and extranodal sites being even rarer. To our knowledge, this is the first reported case of extranodal HS in the foot, emphasizing comprehensive MRI findings. Initially, the patient was diagnosed with TSGCT based on histological results following surgical resection. However, after recurrence and subsequent surgical resection, histological and immunochemical analyses led to a revised diagnosis of HS. This report focuses on the MRI findings of HS, highlighting the distinctions from localized TSGCT. While both conditions share histopathological similarities, immunohistochemical tests are crucial for accurate diagnosis. The report underscores the importance of differentiating HS for appropriate treatment.

A rare case of primary central nervous system histiocytic sarcoma harboring a novel ARHGAP45::BRAF fusion: a case report and literature review

INTRODUCTION

Patients with histiocytic sarcoma occurring in the central nervous system (CNS) are rare and have a very poor prognosis. The increased use of molecular diagnostic approaches in solid tumors has brought more opportunities for the diagnosis and treatment of central nervous system histiocytic sarcoma (CNSHS).

CASE DESCRIPTION

A 9-year-old girl was admitted to the hospital with pain in her head and neck, as well as vomiting. Imaging scans showed a prominent abnormality in the anterior falciform region, and histopathology revealed the presence of CD68 (+) and CD163 (+) cells, leading to a preliminary diagnosis of primary intracerebral CNSHS. Molecular profiling tests identified a new variant of ARHGAP45::BRAF fusion in this case, which has not been reported in any other tumor. The patient underwent surgical removal of the tumor and will require long-term monitoring.

CONCLUSION

The presence of the BRAF point mutation, predominantly BRAF p.V600E, has been documented in prior literature of CNSHS. This is the first case of pediatric histiocytic sarcoma in the anterior falciform region who has a unique ARHGAP45::BRAF fusion. The findings of our study indicate that a broader range of molecular assays should be employed in the diagnosis of CNSHS and opens up new possibilities for the treatment of the patient.

Histiocytic sarcoma of the palate: a case report

Histiocytic sarcoma is a malignant proliferation of cells that exhibit morphological and immunophenotypic features of mature histiocytes. Owing to its rarity, its clinical features and standard treatment have not yet been established. This report describes a case of histiocytic sarcoma of the palate that developed in a 76-year-old man, the first report of an intraoral histiocytic sarcoma. An extended resection was performed; however, establishing the excision line was extremely difficult because assessing the tumour boundary on imaging was challenging and the tumour underwent dynamic gross morphological changes following biopsy. Complete resection is required to obtain a favourable prognosis for high-grade tumours with indistinct borders. In this case, an intraoperative rapid examination with frozen section analysis was performed along the planned excision line to completely resect the tumours exhibiting such behaviour. At 28 months postoperatively, the patient demonstrated no recurrence or metastasis; however, he is under careful monitoring.

Metastatic Histiocytic Sarcoma with Secondary Involvement of the Skin: A Case Report

Histiocytic sarcoma (HS) is a rare malignant neoplasm of presumed hematopoietic origin, showing morphologic and immunophenotypic evidence of histiocytic differentiation. A 61-year-old woman presented with an abdominal mass. She had a history of HS in both adrenal glands. The tumour cells of the left adrenal gland were very large epithelioid cells with abundant eosinophilic cytoplasm and large, round-to-oval nuclei. Similarly, the cutaneous lesion of the skin was composed of polygonal cells with well-defined cell borders and high nuclear/cytoplasm (N/C) ratios. Immunohistochemically, both tumours were positive for histiocyte-associated antigens but negative for epithelial, melanocyte, lymphoid, dendritic, and Langerhansl nuclei. Similarly, the cutaneous lesion of the skin was composenose correctly. It is important to recognise the morphological features and immunohistochemical characteristics of metastatic cells in order to achieve accurate diagnoses.

The changing landscape of pediatric histiocytoses: Birth, life, and transdifferentiation of pediatric histiocytes

Histiocytic neoplasms in the children are very rare, and histiocytoses can occur in the perinatal period. The presumed origins and presentation of specific histiocytoses in the pediatric age group are described. Common and newly described histiocytoses are presented including Langerhans cell histiocytosis, Rosai-Dorfman disease, histiocytic sarcoma, ALK positive histiocytosis, and hemophagocytic lymphohistiocytosis. Molecular findings common to pediatric histiocytoses are also discussed.

Histiocytic sarcoma in renal transplant patients: a literature review

BACKGROUND

Histiocytic sarcoma (HS) is defined as neoplasm resembling morphological and immunophenotypic characteristics of mature histiocytes. It is a rare form of lymphoid neoplasms. Despite advances in treatment and diagnosis of histiocytic sarcoma, majority of cases had poor prognosis due to progressive nature of the disease. In the following article, all reported cases of histiocytic sarcoma in renal transplant patients are reviewed.

METHODS

In our literature review, all relevant reports were collected electronically by entering the necessary keywords. A Boolean approach using Medical Subject Heading (MeSH) keywords was implemented. After establishing the inclusion/exclusion criteria, article titles and abstracts were evaluated by Systematic Reviews and Meta-Analyses (PRISMA) standards for 2020. All cases of histiocytic sarcoma in renal transplant patients were included.

RESULT

Based on our inclusion and exclusion criteria 4 case reports were yielded in this review. Two were males and 2 were females with the mean age of 42.25 years. Fever was the most common symptom. Although tumor originated from the native kidney on one patient, the site of the primary tumor was thorax, oropharynx, and transplanted kidney in the rest. Metastasis was detected in all cases. Prednisone was used for all cases. EBV was positive in 2 cases and negative in one of them. Histology was diagnostic and similar in all cases. Immunohistochemistry was done for 3 cases. Although chemotherapy was done for 3 patients, all 4 cases ended in mortality.

CONCLUSION

Despite the fact that neoplasms are post renal transplant complications, histiocytic sarcoma is a scarce and fatal entity in such patients. Histological and immunohistochemistry tests are the corner stone in diagnosis of histiocytic sarcoma.

Controversies in the Spleen: Histiocytic, Dendritic, and Stromal Cell Lesions

Histiocytic, dendritic, and stromal cell lesions that occur in the spleen are challenging diagnostically, not well studied due to their rarity, and therefore somewhat controversial. New techniques for obtaining tissue samples also create challenges as splenectomy is no longer common and needle biopsy does not afford the same opportunity for examination of tissue. Characteristic primary splenic histiocytic, dendritic, and stromal cell lesions are presented in this paper with new molecular genetic findings in some entities that help differentiate these lesions from those occurring in non-splenic sites, such as soft tissue, and identify possible molecular markers for diagnosis.

Characterization of expression and prognostic implications of GD2 and GD3 synthase in canine histiocytic sarcoma

GD2 and GD3 are disialoganglioside oncofetal antigens important in oncogenesis. GD2 synthase (GD2S) and GD3 synthase (GD3S) are needed for GD2 and GD3 production. The objectives of this study are to validate the use of RNA in situ hybridization (RNAscope®) in the detection of GD2S and GD3S in canine histiocytic sarcoma (HS) in vitro and optimize this technique in canine formalin-fixed paraffin-embedded (FFPE) tissues. A secondary objective is to evaluate the prognostic significance of GD2S and GD3S on survival. Quantitative RT-PCR compared GD2S and GD3S mRNA expression between three HS cell lines followed by RNAscope® in fixed cell pellets from the DH82 cell line and FFPE tissues. Variables prognostic for survival were determined with Cox proportional hazard model. RNAscope® was validated for detection of GD2S and GD3S and optimized in FFPE tissues. GD2S and GD3S mRNA expression was variable between cell lines. GD2S and GD3S mRNA expression was detected and measured in all tumor tissues; there was no association with prognosis. GD2S and GD3S are expressed in canine HS and successfully detected using the high throughput technique of RNAscope® in FFPE samples. This study provides the foundation for future prospective research of GD2S and GD3S utilizing RNAscope®.

Characterization of expression and prognostic implications of transforming growth factor beta, programmed death-ligand 1, and T regulatory cells in canine histiocytic sarcoma

Histiocytic sarcoma (HS) is an aggressive malignant neoplasm in dogs. Expression and prognostic significance of transforming growth factor beta (TGF-β), programmed death-ligand 1 (PD-L1), and T regulatory cells (Tregs) in HS is unknown. The goal of this study was to investigate the expression and prognostic significance of TGF-β, PD-L1, and FoxP3/CD25 in canine HS utilizing RNA in situ hybridization (RNAscope®). After validation was performed, RNAscope® on formalin-fixed paraffin-embedded (FFPE) patient HS tissue samples was performed for all targets and expression quantified with HALO® software image analysis. Cox proportional hazard model was conducted to investigate the association between survival time and each variable. Additionally, for categorical data, the Kaplan-Meier product-limit method was used to generate survival curves. TGF-β and PD-L1 mRNA expression was confirmed in the DH82 cell line by reverse transcription polymerase chain reaction (RT-PCR) and CD25 + FoxP3 + cells were detected by flow cytometry in peripheral blood. Once the RNAscope® method was validated, TGF-β H-score and dots/cell and FoxP3 dots/cell were assessed in HS samples and found to be significantly correlated with survival. Moderate positive correlations were found between FoxP3 and PD-L1 H-score, percent staining area, and dots/cell, and FoxP3 and TGF-β dots/cell. In summary, RNAscope® is a valid technique to detect TGF-β and PD-L1 expression and identify Tregs in canine HS FFPE tissues. Furthermore, canine HS expresses TGF-β and PD-L1. Increased TGF-β and FoxP3 correlated with worse prognosis. Prospective studies are warranted to further investigate TGF-β, PD-L1, and Tregs effect on prognosis.

A long-term survival case of histiocytic sarcoma by surgery alone in a Japanese elderly breast tumor patient

INTRODUCTION

Histiocytic sarcoma (HS) is a rare hematologic malignancy. HS of the breast is extremely rare, and we present a case of an elderly patient with breast HS.

CASE PRESENTATION

An 81-year-old woman with unremarkable past medical and family histories presented to our hospital with a palpable mass in her right upper breast. She had noticed a mass in her right breast 3 months before her first visit. Physical examination revealed a mass measuring approximately 30 mm in the right upper quadrant of the breast; there were no cervical or axillary lymphadenopathies. Mammography revealed a high-concentration mass with unclear margins in the upper and outer breast. Ultrasound and magnetic resonance imaging (MRI) revealed a 31 × 23-mm nodule with a relatively clear margin and necrotic sign on the T2-intensified image. A mastectomy was performed upon the patient's request, and the surgical specimen revealed a 35-mm hemorrhagic mass. The lesion was estrogen receptor-, progesterone receptor-, and HER2/neu-negative. The Ki-67 labeling index was approximately 30%. The immunohistochemical panel showed immune reactivity for the histiocytic markers CD68, CD163, and CD206 and was immune-negative for B lineage, T lineage, Langerhans cells, and keratins. The diagnosis of HS was based on the morphological and immunophenotypic characteristics of the mass. The patient received no systemic therapy and survived for 50 months without recurrence.

CONCLUSIONS

Here, we report the case of an elderly patient with rare breast HS. Although the prognosis of HS seems poor, the breast HS was not as poor as expected, since it might have been discovered in the local region before it metastasized.

Multiple disciplinary team management of rare primary splenic malignancy: Two case reports

BACKGROUND

Malignant splenic tumors are rare but fatal, presenting a challenge in diagnosis and management involving hematology, oncology, and general surgery. By contrast, diagnosing and treating other common malignant tumors (such as lung and gastrointestinal cancer) offers multiple strategies for chemotherapy, radiotherapy, targeted therapy, and immunotherapy with the prospect of a cure. With various specialists involved in clinical multiple disciplinary team (MDT) discussion, personal bias can be minimized. It can also ignite important discussion which can benefit not only one patient but many patients.

CASE SUMMARY

Here, we report on the MDT diagnosis and management of the malignant splenic tumors littoral cell angiosarcoma and histiocytic sarcoma. Although only two cases of rare primary splenic malignancy are presented, MDT is a novel means of rare disease treatment.

CONCLUSION

To benefit patients, imaging analysis, safe operation, precise pathology examination, and individualized therapeutic treatment strategies are required. The involvement of various specialists in a clinical MDT discussion minimizes personal bias and can create important ideas to benefit all patients.

PAX5 P80R-mutated B-cell acute lymphoblastic leukemia with transformation to histiocytic sarcoma: clonal evolution assessment using NGS-based immunoglobulin clonality and mutation analysis

Clonality assessment by the detection of immunoglobulin (IG) gene rearrangements is an important method to determine whether two concurrent or subsequent lymphoid malignancies in one patient are clonally related. Here, we report the detailed clonality analysis in a patient with a diagnosis of B-cell acute lymphoblastic leukemia (B-ALL) followed by a histiocytic sarcoma (HS), in which we were able to study clonal evolution by applying next generation sequencing (NGS) to identify IG rearrangements and gene mutations. Using the sequence information of the NGS-based IG clonality analysis, multiple related subclones could be distinguished in the PAX5 P80R-mutated B-ALL. Notably, only one of these subclones evolved into HS after acquiring a RAF1 mutation. This case demonstrates that NGS-based IG clonality assessment and mutation analysis provide clear added value for clonal comparison and thereby improves clinicobiological understanding.

Lymph node recurrence and re-excision after primary tumor resection of a histiocytic sarcoma of duodenal origin: a case report

BACKGROUND

Histiocytic sarcoma is a rare malignant tumor that is similar in characteristics to a mature histiocyte/macrophage and is a relatively new disease entity. In approximately one-third of cases, the site of origin is a lymph node; development from the gastrointestinal tract, spleen, soft tissue, and skin has further been reported. The tumor characteristics are not well-understood as reports on its clinical presentation and treatment are limited. We report a case of duodenal primary histiocytic sarcoma.

CASE PRESENTATION

An elevated lesion in the second part of the duodenum was detected in a 70-year-old woman during routine examination using upper gastrointestinal tract endoscopy. Blood biochemistry findings were normal for tumor markers. No abnormal findings were observed in the blood count and biochemical examination. Upper gastrointestinal endoscopy revealed a 20-mm elevated lesion with a slight depression in the center, opposite to the papilla of the descending duodenum. The biopsy showed erosions of the mucosal epithelium and inflammatory cell infiltration, but no evidence of malignancy. Ultrasound-guided endoscopy revealed an ischemic tumor of submucosal origin, and bowel biopsy suggested a histiocytic sarcoma. Distant metastasis and lymph node enlargement were absent on abdominal sonography, computed tomography, and magnetic resonance imaging. Duodenal segmental resection was performed. Immunostaining of the excised lesion was positive for CD68, CD163, CD4, CD5, CD15, and CD45 and negative for CD1a, CD21, CD34, MPO, and S-100 protein. Ki-67 positivity was approximately 20%. Based on these findings, the diagnosis of histiocytic sarcoma was confirmed. Ten months after the surgery, a lymph node recurrence in the dorsum of the pancreatic uncus was observed. No evidence of recurrence was found in any other part; hence, we performed pancreaticoduodenectomy. Pathological findings of the excised lymph node confirmed the recurrence of histiocytic sarcoma in the lymph node.

CONCLUSIONS

This is the first reported case of a duodenal primary histiocytic sarcoma with recurrence in the lymph node after the primary resection. The patient was treated for recurrence by lymph node excision and pancreaticoduodenectomy.

Histiocytic Sarcoma With CCND1 Gene Rearrangement Clonally Related and Transdifferentiated From Mantle Cell Lymphoma

OBJECTIVES

Histiocytic neoplasms demonstrate shared gene translocations and clonal immunoglobulin gene rearrangements in cases of associated B-cell lymphomas. However, the evolution of these related disease processes remains largely uncertain, especially in the setting of a prior mantle cell lymphoma.

METHODS

We describe a unique case of a histiocytic sarcoma that transdifferentiated from blastoid mantle cell lymphoma after extensive therapy. Cytogenic and molecular studies were performed and provided evidence for clonal progression.

RESULTS

We present the first reported case of a patient with blastoid mantle cell lymphoma harboring a CCND1 rearrangement that progressed despite multiple therapeutic regimens and ultimately transdifferentiated into histiocytic sarcoma. The histiocytic sarcoma demonstrated a CCND1 rearrangement and targeted next-generation sequencing showed a pathogenic variant in NRAS, a gene involved in the RAS/MAPK pathway, known to play a role in the pathogenesis of histiocytic sarcomas. TP53, NOTCH2, CREBBP, and NFKBIE variants were also identified, which are often seen in B-cell lymphomas, while rarely described in histiocytic sarcoma.

CONCLUSIONS

To our knowledge, this is the first report to provide evidence for clonal evolution of histiocytic sarcoma from blastoid mantle cell lymphoma based on cytogenic and molecular findings. The patient's protracted therapeutic course may have acted as an evolutionary driver promoting this transdifferentiation process.

Histiocytic and dendritic cell neoplasms

BACKGROUND

Histiocytic and dendritic cell neoplasms (HDCNs) represent very rare tumors, which have been the subject of debate during the last few years.

OBJECTIVES

We aimed to provide a comprehensive review of the subject.

MATERIALS AND METHODS

The experience gained by the authors in large international studies and as a national reference center has been summarized to highlight the characteristics of each entity.

RESULTS

The clinical, morphologic, phenotypic, and molecular data of the different entities included under the heading of HDCNs are extensively discussed.

CONCLUSION

Currently, HDCNs are classified in the group of orphan diseases for which a standardized therapy is lacking. An international registry would facilitate expansion and dissemination of knowledge of these diseases and improve their treatment.

Malignant histiocytosis associated with mediastinal germ cell tumor: A case report

BACKGROUND

Germ cell tumors (GCTs) account for 2% of human malignancies but are the most common malignant tumors among males aged 15-35. Since 1983, an association between mediastinal GCT (MGCT) and hematologic malignancies has been recognized.

CASE SUMMARY

We report a case in which malignant histiocytosis was associated with mediastinal GCTs. The clinical data of a male patient with MGCT admitted to Beijing Children's Hospital were collected retrospectively. The patient was first diagnosed according to imaging and pathological features as having MGCT, and was treated with surgery and chemotherapy. One year after stopping chemotherapy, imaging showed metastases in the right supraclavicular, mediastinum, hilar region and retroperitoneal lymph node, right pleura, right lung, and right para-cardiac margin. Pathological diagnosis of the liver nodular and hilar lymph nodes included systemic juvenile xanthogranuloma and Rosai-Dorfman lesions with malignant transformation (i.e., morphological characteristics and immunophenotype of histiocytic sarcoma). Following diagnosis, the patient accepted chemotherapy with vindesine, cytarabine and dexamethasone. Positron emission tomography–computed tomography showed partial remission. The patient was followed-up for 10 mo after the diagnosis of malignant histiocytosis, and no sign of progression or relapse was observed.

CONCLUSION

Physicians should recognize the possibility of hematologic malignancies being associated with MGCT. Suitable sites should be selected for pathological examination.

A case of primary histiocytic sarcoma arising from a neck lymph node

Histiocytic sarcoma (HS) is an aggressive and rare hematological malignancy. Its treatment has not been established, and most patients die within 2 years of diagnosis. Resection can provide a favorable prognosis for solitary lesions. We present the case of an 80-year-old Japanese man with HS. He presented a history of a slow-growing painless mass in the lower part of his right jaw. Ultrasonography showed a swollen lymph node in the vicinity of the right submandibular gland. Contrast-enhanced computed tomography revealed a heterogeneous, low-contrast mass on the right of the neck. Magnetic resonance imaging revealed a heterogeneously enhanced mass in gadolinium-enhanced T1-weighted images. The fine needle biopsy showed spindle-shaped cells and HS was suspected. Fluorodeoxyglucose positron emission tomography revealed uptake by the tumor alone. The patient underwent right upper neck dissection and resection of the submandibular salivary glands. No postoperative adjuvant treatment was administered, but 2-year survival was achieved. Histopathological examination showed proliferation of large, pleomorphic atypical cells without differentiation into lymphocytes, which proved their differentiation into histiocytes. A bone marrow biopsy showed no evidence of monocytic leukemia. Thus, a diagnosis of HS was made. With local treatment alone, our patient achieved long-term survival, maintaining his quality of life.

Increased tumor-infiltrating lymphocyte density is associated with favorable outcomes in a comparative study of canine histiocytic sarcoma

Histiocytic sarcoma (HS) is a rare and aggressive tumor in humans with no universally agreed standard of care therapy. Spontaneous canine HS exhibits increased prevalence in specific breeds, shares key genetic and biologic similarities with the human disease, and occurs in an immunocompetent setting. Previous data allude to the immunogenicity of this disease in both species, highlighting the potential for their successful treatment with immunotherapy. Quantification of CD3 tumor-infiltrating lymphocytes (TIL) in five cases of human HS revealed variable intra-tumoral T cell infiltration. Due to the paucity of human cases and lack of current model systems in which to appraise associations between anti-tumor immunity and treatment-outcome in HS, we analyzed clinical data and quantified TIL in 18 dogs that were previously diagnosed with localized HS and treated with curative-intent tumor resection with or without adjuvant chemotherapy. As in humans, assessment of TIL in biopsy tissues taken at diagnosis reveal a spectrum of immunologically "cold" to "hot" tumors. Importantly, we show that increased CD3 and granzyme B TIL are positively associated with favorable outcomes in dogs following surgical resection. NanoString transcriptional analyses revealed increased T cell and antigen presentation transcripts associated with prolonged survival in canine pulmonary HS and a decreased tumor immunogenicity profile associated with shorter survivals in splenic HS. Based on these findings, we propose that spontaneous canine HS is an accessible and powerful novel model to study tumor immunology and will provide a unique platform to preclinically appraise the efficacy and tolerability of anti-cancer immunotherapies for HS.

Oral histiocytic sarcoma in a cat with mandibular invasion and regional lymph node metastasis

Case summary

An 11-year-old female spayed domestic medium-hair cat presented for dental prophylaxis, at which time no oral mass was appreciated. Fifteen days after a dental cleaning, a mass expanding the oral mucosa of the rostral mandible was identified. An incisional biopsy revealed that the oral mucosa was infiltrated by neoplastic round-to-spindloid mesenchymal cells arranged in streams and small, dense aggregates consistent with an undifferentiated sarcoma. The patient was managed medically for approximately 6 months following the diagnosis, but, owing to declining health, euthanasia was elected and a post-mortem examination was performed. On post-mortem examination, the previously described neoplastic cells were infiltrating the rostral mandible and had metastasized to the right submandibular lymph node. Immunohistochemistry performed during the postmortem examination found that neoplastic cells were positive for Iba-1, CD18 and CD204, and negative for MUM-1, S100, Melan-A and E-cadherin, favoring a diagnosis of oral histiocytic sarcoma. Although recently recognized in cats, feline oral histiocytic sarcoma is rare, the tumor’s immunohistochemical profile is unstandardized, and the tumor’s behavior and prognosis are unclear. The diagnosis is challenging if small incisional biopsies are submitted and the neoplasm is poorly differentiated. This case report discusses the clinical, macroscopic, microscopic and immunohistochemical features of oral histiocytic sarcoma in a cat with mandibular invasion and submandibular lymph node metastasis.

Relevance and novel information

Feline primary oral histiocytic sarcoma is rare and tumor behavior and prognosis are unclear. This report broadens the immunohistochemical features of the tumor and recognizes mandibular invasion and submandibular lymph node metastasis.

Small bowel and lung histiocytic sarcoma revealed by acute peritonitis: A case report with review of literature

INTRODUCTION AND IMPORTANCE

Histiocytic sarcoma (HS) is a rare malignant neoplasm showing morphologic and immunohistochemical features of histiocytes. It is characterized typically by extranodal presentation and a poor clinical course, particularly in cases with disseminated disease.

CASE PRESENTATION

This report documents a case of bifocal and aggressive HS in small bowel and lung revealed by acute peritonitis in a 63-year-old man.

CLINICAL DISCUSSION

Despite its rarity, we believe that the correct diagnosis of HS is crucial for clinical treatment and prognostic prediction.

CONCLUSION

The collection of additional cases of HS are important to obtain further progress in prognosis and guide treatment decisions.

Disseminated mucocutaneous trichosporonosis in a patient with histiocytic sarcoma

Trichosporon asahii is the causal agent of trichosporonosis. Patients with immunosuppression or hematological malignancies are at higher risk of infection. Skin and mucosal involvement appear as fast-growing papulonodular lesions and necrotic ulcers. Internal organ dissemination is lethal. Therapeutic success depends on the underlying disease. Here, the authors present the first case of disseminated mucocutaneous trichosporonosis in a patient with a post-mortem diagnosis of histiocytic sarcoma, a rare and aggressive haematolymphoid neoplasm. Regretfully, death occurred despite treatment with liposomal amphotericin B and supportive measures, showcasing the fatality of both diseases.

An advanced case of gastric histiocytic sarcoma treated with chemotherapy and gastrectomy: a case report and review of literature

Histiocytic sarcoma is a relatively new disease category and the gastrointestinal origin is sporadic. We report a case of a 74-year-old woman who underwent chemotherapy and proximal gastrectomy for extremely rare, advanced gastric histiocytic sarcoma. The resected specimen was subjected to numerous immunostainings to meet the diagnostic criteria of histiocytic sarcoma and was positive for the histiocyte markers' cluster of differentiation 68 and lysozyme. The markers of Langerhans cells, follicular dendritic cells, and myelocyte were all negative. Six reports of surgical resection of histiocytic sarcoma originating in the stomach exist, including our case. We reviewed the clinical course and the histological and immunohistochemical diagnostic features of surgically resected gastric histiocytic sarcoma.

Balancing risk in a patient with primary bone histiocytic sarcoma during pregnancy: Case report and review of the literature

INTRODUCTION AND IMPORTANCE

Histiocytic sarcoma (HS) is a rare, aggressive malignant neoplasm of hematopoietic cell origin. Primary HS of the proximal humerus, without involvement of lymph nodes or bone marrow, or systemic features, is very rare.

CASE PRESENTATION

We report a rare case of primary bony HS of the proximal humerus without bone marrow involvement in a healthy 33-year-old pregnant woman. She was successfully treated with surgical resection during pregnancy and radiotherapy post-delivery.

CLINICAL DISCUSSION

This is the first report of a patient with primary bony HS during pregnancy. This highlights the fact that although HS is a neoplasm of hemolymphoid cell lineage, it frequently arises in non-lymphoid organs.

CONCLUSION

This case emphasizes the importance of a multidisciplinary approach and the need for balancing treatment risk in a patient with primary bone HS during pregnancy.

Histiocytic sarcoma arising from a lymph node: a diagnostic conundrum

Histiocytic Sarcoma (HS) is extremely rare, with only a few hundred cases reported in the literature. The majority of patients present with symptoms due to unifocal or multifocal extra-nodal disease. Less than 20% of these cases show solitary involvement of a lymph node. We report a case of a solitary HS in a 53-year-old woman presenting with a 2.7-cm right groin mass arising from an inguinal lymph node. The initial cytologic examination of the tissue showed a high-grade spindle-shaped morphology with high-grade mitotic activity. A high-grade sarcoma was initially considered considering the absence of normal lymphoid aggregate and the presence of high-grade cytologic features in the cells. To evaluate the tumor in its entirety, the mass was surgically excised. A histological examination of the tumor showed focal rimming of the lymphoid tissue at the periphery and a centrally located stellate necrotic focus. The tumor cells had an epithelioid to spindle cell morphology along with large uniform nuclei and prominent nucleoli. A high mitotic index was present. Immunohistochemistry (IHC) stains showed strong positivity for CD68, CD163, and Vimentin, and were weakly positive for SMA and CD45. Based on the histologic and clinical examination, a diagnosis of HS was made. Multiple malignancies can mimic HS histopathology and the rarity of this tumor makes the diagnosis more challenging. No fine-needle aspiration (FNA) criteria for its diagnosis have been recognized. Herein, we report a rare case of an isolated HS involving a lymph node which resembled high-grade sarcoma on the FNA biopsy to raise awareness among our surgical pathologist colleagues.

Histiocytic and Dendritic Cell Sarcomas of Hematopoietic Origin Share Targetable Genomic Alterations Distinct from Follicular Dendritic Cell Sarcoma

Background

Histiocytic and dendritic cell neoplasms are a diverse group of tumors arising from monocytic or dendritic cell lineage. Whereas the genomic features for Langerhans cell histiocytosis and Erdheim‐Chester disease have been well described, other less common and often aggressive tumors in this broad category remain poorly characterized, and comparison studies across the World Health Organization diagnostic categories are lacking.

Methods

Tumor samples from a total of 102 patient cases within four major subtypes of malignant histiocytic and dendritic cell neoplasms, including 44 follicular dendritic cell sarcomas (FDCSs), 41 histiocytic sarcomas (HSs), 7 interdigitating dendritic cell sarcomas (IDCSs), and 10 Langerhans cell sarcomas (LCSs), underwent hybridization capture with analysis of up to 406 cancer‐related genes.

Results

Among the entire cohort of 102 patients, CDKN2A mutations were most frequent across subtypes and made up 32% of cases, followed by TP53 mutations (22%). Mitogen‐activated protein kinase (MAPK) pathway mutations were present and enriched among the malignant histiocytosis (M) group (HS, IDCS, and LCS) but absent in FDCS (72% vs. 0%; p < .0001). In contrast, NF‐κB pathway mutations were frequent in FDCSs but rare in M group histiocytoses (61% vs. 12%; p < .0001). Tumor mutational burden was significantly higher in M group histiocytoses as compared with FDCSs (median 4.0/Mb vs. 2.4/Mb; p = .012). We also describe a pediatric patient with recurrent secondary histiocytic sarcoma treated with targeted therapy and interrogated by molecular analysis to identify mechanisms of therapeutic resistance.

Conclusion

A total of 42 patient tumors (41%) harbored pathogenic mutations that were potentially targetable by approved and/or investigative therapies. Our findings highlight the potential value of molecular testing to enable precise tumor classification, identify candidate oncogenic drivers, and define personalized therapeutic options for patients with these aggressive tumors.

Implications for Practice

This study presents comprehensive genomic profiling results on 102 patient cases within four major subtypes of malignant histiocytic and dendritic cell neoplasms, including 44 follicular dendritic cell sarcomas (FDCSs), 41 histiocytic sarcomas (HSs), 7 interdigitating dendritic cell sarcomas (IDCSs), and 10 Langerhans cell sarcomas (LCSs). MAPK pathway mutations were present and enriched among the malignant histiocytosis (M) group (HS, IDCS, and LCS) but absent in FDCSs. In contrast, NF‐κB pathway mutations were frequent in FDCSs but rare in M group histiocytosis. A total of 42 patient tumors (41%) harbored pathogenic mutations that were potentially targetable by approved and/or investigative therapies.

Histiocytic and dendritic cell neoplasms are a diverse group of tumors arising from the monocytic or dendritic cell lineage. This article presents the molecular characteristics of the four major subtypes of malignant histiocytic and dendritic cell neoplasms, focusing on genomic alterations that could represent therapeutic targets.

Histiocytic sarcoma following combination chemotherapy for primary mediastinal germ cell tumor: a diagnostic dilemma

Histiocytic sarcoma is considered an extremely rare condition. We herein report on a case of histiocytic sarcoma following combination chemotherapy for a primary mediastinal germ cell tumor in a 26-year-old Asian man who visited the General Medicine Department of a hospital with complaints of cough and high fever. Chest computed tomography (CT) imaging revealed a tumor (diameter 10.5 cm) in the anterior mediastinum, with no signs of metastasis, and CT-guided biopsy of the mediastinal tumor revealed the presence of some necrotic cartilages. The patient's serum α-fetoprotein (AFP) level was determined to be high at 160.4 ng/mL and a primary mediastinal non-seminomatous germ cell tumor was suspected, so the patient was referred to the Department of Urology. Despite the presence of severe thrombocytopenia, the patient was treated using a combination of chemotherapy and intermittent transfusion, which was able to normalize his serum AFP level. However, resection of the mediastinal tumor was unsuccessful due to persistent thrombocytopenia and the patient was subsequently transferred to our hospital for further examination and treatment. Despite management by hematologists, the condition of the patient did not improve; although his AFP level remained normal, the tumor increased in size and then metastasized to the liver and spleen. The general condition of the patient deteriorated and he died 9 months after his first visit. The patient was diagnosed with histiocytic sarcoma following a pathological autopsy. Due to the extremely rare incidence of histiocytic sarcoma, this condition should be a differential diagnosis and the appropriate tests must be conducted to give an exact treatment.

Nodal histiocytic sarcoma with prominent eosinophilic infiltration: expression of eotaxin-2 on tumor cells

Background

Histiocytic sarcoma (HS) is a rare neoplasm showing morphological and immunophenotypic features of mature tissue histiocytes. We report a patient with nodal HS exhibiting prominent reactive eosinophilic infiltration.

Case presentation

A 68-year-old man presented with intermittent left lower abdominal pain and weight loss over 3 months. A computed tomography scan revealed multiple abdominal nodules. Open biopsy of the mesenteric tumors was performed for definitive diagnosis. Histologically, the tumor was comprised of a diffuse noncohesive proliferation of pleomorphic large cells, including multinucleated cells. Neoplastic cells were positive for histiocytic markers (CD68, CD163, and LIGHT) and PD-L1 but lacked markers of Langerhans cells, follicular dendritic cells, and epithelial cells. Frequent reactive inflammatory cells were intermingled in the background. Interestingly, prominent eosinophilic infiltration was also noted. Spindle neoplastic cells were prone to be present around areas with little to no eosinophilic infiltration and exhibiting fibrosis and lymphatic vessel proliferation. Conversely, polygonal neoplastic cells were prone to be present around areas with relatively large amounts of eosinophilic infiltration without fibrosis or lymphatic vessel proliferation. Immunohistochemically, the tumor cells and reactive eosinophils expressed eotaxin-2 and eotaxin-3, respectively.

Conclusion

We revealed that eotaxins induced the selective migration of eosinophils into tissues in this case. These eosinophils may affect the tumor remodeling and tumor biology characteristics of HS, such as fibrosis and lymphatic vessel proliferation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13000-020-01061-4.

Case report on unusual tumor with synchronous cutaneous and gastrointestinal tract involvement

Histiocytic sarcoma (HS) is an exceedingly rare lymphohematopoietic malignancy with morphological and immunophenotypic characteristics of mature tissue histiocytes. We report a unique case of a HS with synchronous skin and gastrointestinal tract involvement which has not been reported in literature till date to the best of our knowledge. A 70-year-old male farmer presented with multiple ulcerated skin lesions ranging from 0.5 to 10 cm all over the body. Autopsy revealed multiple transmural nodular deposits in stomach, intestines, head of pancreas, and peripancreatic tissue. Histopathology and immunohistochemistry profile was consistent with HS exhibiting positivity for CD68, CD163, and lysozyme. CD 163 identifies histiocytic malignancies with high degree of specificity and has become a promising marker for their diagnosis.

Oral histiocytic sarcoma in a cat

Case summary

A 15-year-old neutered male domestic shorthair cat presented with a 4-week history of dysphonia and reluctance to chew hard food. Oral examination revealed a mass lesion on the caudal soft palate. Biopsy was performed and histopathology with immunohistochemistry was most consistent with histiocytic sarcoma. CT of the head identified a discrete, left-sided, soft tissue mass lesion cranial to the tonsil with bilaterally symmetrical regional lymph nodes. CT of the thorax was unremarkable. Surgical removal achieved cytoreduction but not complete removal. Adjuvant chemotherapy with lomustine 10 mg (30 mg/m²) was initiated. The patient developed suspected pancreatitis 2–3 weeks postoperatively, so further chemotherapy treatment was discontinued, but supportive treatment with pain relief and appetite stimulants was provided. Three months postoperatively, the patient developed recurrent dysphonia, and oral examination revealed a suspicion of local recurrence. Confirmation of diagnosis (cytopathology or histopathology) was not obtained. Supportive treatment to maintain a good quality of life was continued and the patient was euthanased 6 months after diagnosis owing to progressive disease.

Relevance and novel information

Only a few reports have been published describing histiocytic diseases of cats. To our knowledge, this is the first report of a feline histiocytic sarcoma of the oral cavity. Therefore, histiocytic sarcoma should be considered as a differential diagnosis in feline patients with an oral mass, especially if histopathology suggests a pleomorphic and poorly differentiated sarcoma. Immunohistochemistry for the confirmation of cell line origin would be strongly recommended.

Leukemic Phase of Histiocytic Sarcoma of the Digestive System: A Rare Manifestation of a Rare Disease

Histiocytic sarcoma (HS) is a rare, malignant, and aggressive subtype of histiocytosis. We present an unusual case of aggressive HS presenting in the gastrointestinal tract and gallbladder that progressed after several lines of chemotherapy with a leukemic phase. We review the clinical, pathological, and molecular characteristics of HS in this case and review the literature on HS involving the digestive system as well as on overt leukemic phase of this disease. HS is often diagnosed at an advanced stage, and mortality is high. We discuss the therapeutic approach to patients with HS. We highlight the role of overexpression and somatic alterations in the RAF-MEK-ERK pathway in the pathogenesis of HS and discuss potential targeted approaches to treat these rare tumors.

Thrombocytopenia with multiple splenic lesions - histiocytic sarcoma of the spleen without splenomegaly: A case report

BACKGROUND

Histiocytic sarcoma (HS) of the spleen is reported to be a rare and lethal disease. The clinicopathological features of splenic HS have not been well described. The objective of this paper is to describe the diagnosis and treatment of a case of this rare disease and provide a review of the literature.

CASE SUMMARY

In this article, we discuss the case of a 40-year-old Hispanic female who presented with progressive thrombocytopenia and multiple hypoechoic lesions in the spleen without splenomegaly. Positron emission tomography-computed tomography showed increased activity in cervical lymph nodes, as well as multiple bone and splenic lesions with positive uptake. Two bone marrow biopsies and fine-needle aspiration of the cervical lymph node were inconclusive. Laparoscopic splenectomy was performed, and gross examination showed a 110.1 g spleen with multiple rubbery, nodular lesions within the subcapsular sinus and splenic parenchyma. The microscopic findings showed multinodular histiocyte proliferation with atypia and multilobulated nuclei, which were positive for CD163, CD4, and CD68 by immunohistochemical analysis. The final pathologic diagnosis was difficult and was found to be low-grade HS of the spleen, after consultations with two renowned hematopathology institutions. At the patient’s five-month follow-up visit, her bone marrow metastasis had progressed. She is waiting to be enrolled in a clinical trial.

CONCLUSION

Pathologic diagnosis of splenic HS can be challenging. Low-grade differentiation may be associated with a slow progressive disease.

CLIPPERS, a syndrome of lymphohistiocytic disorders

BACKGROUND

CLIPPERS (chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids) is a chronic central nervous system (CNS) inflammatory disorder. It may be associated with lymphoma and macrophage activation, while the related report of histiocytes (macrophage) activation involved in pathogenesis of CLIPPERS is rare. We present the first "probable CLIPPERS" case associated with histiocytic sarcoma (HS) progressed to hemophagocytic syndrome (HPS) in a 38-year-old man patient.

CASE PRESENTATION

The 38-year-old man presented with facial numbness, diplopia, gait ataxia and glossolalia for 29 months. Brain MRI showed gadolinium enhancement peppering the pons and extending into the midbrain, medulla, brachium pontis, cerebellum and thalamus. The patient's CNS symptoms were improved significantly and accompanied by marked radiological improvement after glucocorticoids therapy, while the disease courses presented relapsing-remitting and glucocorticoids-dependent. Multiple nodules in the abdomen were accidentally discovered by the abdominal Computed tomography (CT) during the remission period. HS was diagnosed by histological examination of the abdominal node biopsy accompanied by CLIPPERS relapse, and eventually progressed to HPS.

CONCLUSIONS

CLIPPERS could be a syndrome of lymphohistiocytic disorders.

Histiocytic sarcoma of the base of tongue treated with radical radiotherapy: A case report and review of the literature

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First report in literature of curative management with radiotherapy for histiocytic sarcoma.

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Radiotherapy to localised base of tongue histiocytic sarcoma was well tolerated.

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No evidence of relapse following 5 years follow up.

Histiocytic sarcoma (HS) is an exceedingly rare and aggressive neoplasm of lymphoid and haematopoietic tissues and expresses histological and phenotypical characteristics of mature histiocytes. There have only been a few cases of documented HS in the head and neck region. Whilst patients with HS often have nodal or disseminated disease, patients can present with localised disease. There are currently no established treatment guidelines, and reported cases of localised disease have been managed with primary surgery and adjuvant radiotherapy and/or chemotherapy. Here we present, the case of a 49 year old man with a HS of the base of tongue treated with radical radiotherapy to a dose of 60 Gy in 30 fractions, achieving disease free survival of greater than 5 years with minimal toxicity. To our knowledge, this is the first reported case of HS treated with radical radiotherapy, and suggests that when the potential morbidity of surgery for localised disease is significant, radiotherapy may represent an alternative treatment.

Subsequent development of histiocytic sarcoma and follicular lymphoma: cytogenetics and next-generation sequencing analyses provide evidence for transdifferentiation of early common lymphoid precursor-a case report and review of literature

Histiocytic sarcoma (HS) is a rare aggressive hematologic neoplasm that can be associated with low-grade B cell lymphoma. The development of both neoplasms is currently being considered a transdifferentiation mechanism but remains elusive. We report the case of a 65-year-old patient with synchronous development of peritoneal/abdominal HS and grade 1-2 follicular lymphoma (FL). Cytogenetic analysis and targeted next-generation sequencing of both FL and HS tumors identified common genomic alterations such as IGH-BCL2 rearrangement, CREBBP and KMT2D, and aberrations of chromosomes 9q and 19q. However, only the HS tumor had a KRAS mutation while the lymph node involved by FL harbored a TNFAIP3 mutation and both tumors also showed distinct chromosomal alterations. This report strengthens the hypothesis of a common lymphoid progenitor which accumulates genetic alterations leading to two different hematologic malignant diseases with significantly distinct prognoses.

Primary Histiocytic Sarcoma Presenting as a Breast Mass: A Case Report

Histiocytic sarcoma is a rare hematologic malignancy, with very few cases of primary histiocytic sarcoma of the breast described in English scientific literature. Herein, we describe a case of primary histiocytic sarcoma of the breast in a 75-year-old woman, with no clinical history of malignant tumors, who presented with a palpable solitary breast mass. Microscopically, the resected breast mass showed large pleomorphic cells, some multinucleated giant cells, and admixed inflammatory components. The pleomorphic tumor cells further showed a diffuse, noncohesive growth pattern, an abundant eosinophilic cytoplasm, and strong and diffuse immunoreactivity for cluster of differentiation (CD) 68 and CD163. Furthermore, a whole-body positron-emission tomography/computed tomography using deoxy-2-[¹⁸F]fluoro-D-glucose performed after surgery showed no other masses or lesions. After surgical excision, the patient was followed up, and no evidence of tumor recurrence or metastasis was noted.

Histiocytic Sarcoma Following B-Lymphoblastic Leukemia/Lymphoma

OBJECTIVES

Rare cases of clonally related histiocytic sarcoma (HS) following B-lymphoblastic leukemia/lymphoma (B-ALL/LBL) have been reported to date.

METHODS

We present a patient with HS, which appeared as a breast mass 12 months after the initial diagnosis of B-ALL.

RESULTS

Both HS and the B-ALL shared IGH-MYC and IGK gene rearrangements. Next-generation sequencing and whole-exome sequencing (WES) studies detected 35 common mutations, as well as mutations unique to B-ALL (16) and HS (15), including BRAF D594G. The patient achieved complete remission of B-ALL, but HS failed to respond to many cycles of intensive chemotherapy regimens. A partial response was achieved with sorafenib, a BRAF-targeted therapy.

CONCLUSIONS

To our knowledge, this is the first study to demonstrate by WES that clonally related B-ALL and HS arise through divergent evolution from a common precursor. We present our findings together with a discussion of the previously reported cases of HS in patients with B-ALL.

Histiocytic sarcoma of the eyelid

Histiocytic Sarcoma is a rare malignant hematopoietic neoplasm that can present in extranodal sites including lymph nodes, skin, gastrointestinal tract, and the central nervous system. Only 10% of cases manifest as skin lesions and very few are reported in the head and neck. The authors report a case of histiocytic sarcoma of the eyelid in a 72-year-old male that was clinically diagnosed as a chalazion. Initial excision was not sent for routine histopathological assessment and the patient was subsequently lost to follow up. Recurrence occurred at the eyelid site and additional lesions were found on the forearms, abdomen, and right knee. Histopathological assessment of one of these other sites confirmed the diagnosis of histiocytic sarcoma. To our knowledge, this is the first reported case of disseminated histiocytic sarcoma that originally presented in the ocular adnexa (eyelid). And, as the initial lesion was not sent to Pathology and therefore potentially missed, this case highlights the importance of submitting tissue, including chalazia, for pathologic evaluation.

A novel surgical approach with peritonectomy to extranodal multisystemic histiocytic sarcoma: A case report and literature review

INTRODUCTION

Histiocytic sarcoma (HS) is a very rare malignant histiocytic derivation cancer. The extranodal multisystemic HS has an aggressive clinical course and poor Disease-Free Survival (DFS) and Overall Survival (OS). There are no shared and effective therapeutic protocols; our approach aims to improve the prognosis for advanced diseases.

PRESENTATION OF THE CASE

53-year-old female patient admitted to hospital for intestinal obstruction in April 2016 with evidence of an ileal mass in the right iliac fossa and peritoneal metastases, undergoing urgent surgery of ileal resection, ileostomy and nodular peritoneal mass biopsy. Histological examination diagnosed HS. Staging exams excluded the involvement of other gastro-intestinal districts in the absence of concomitant lymphoproliferative disorders, and PET-CT revealed multiple abdominal and mediastinal nodes hyperplasia. The patient performed chemotherapy and, seeing the partial abdominal extranodal response, was performed cytoreductive surgery (CRS). Histological examination confirmed the diagnosis of HS with multiple peritoneal, ileal, colic and omental localisation. Adjuvant second-line chemotherapy treatment (4 DHAP cycles) was performed. Disease Free Survival at ten months from cytoreductive surgery, Overall Survival at 21 months from diagnosis.

DISCUSSION

Despite a multimodal therapy with surgery and chemotherapy, extranodal multisystemic HS has a poor prognosis. Up to now the role of surgery is limited to biopsies or complications treatment. Our results of DFS and OS show that cytoreductive surgery may be a valid therapeutic choice.

CONCLUSION

The surgical approach with major cytoreductive purposes could improve the prognosis in cases with prevalent abdominal extranodal localisation.

Histiocytic and Dendritic Cell Neoplasms

Histiocytic and dendritic cell neoplasms are very rare, belonging to a group that share morphologic, immunophenotypic, and ultrastructural characteristics of mature histiocytic/dendritic neoplasms. Histiocytic and dendritic cell neoplasms may arise de novo or in association with B-cell, T-cell, or myeloid neoplasms. Recent molecular findings, particularly the discoveries of the mutations in the RAS-RAF-MEK-ERK pathway, have greatly advanced the diagnosis and treatment options. Histiocytic and dendritic cell neoplasms may closely resemble each other, non-hematopoietic neoplasms, and even reactive processes. Therefore, it is essential to understand the clinicopathologic characteristics, differential diagnoses, and pitfalls of each entity.

Histiocytic Sarcoma and Hemangiosarcoma Update

Histiocytic sarcoma (HS) and hemangiosarcoma (HSA) are uncommon and aggressive neoplasms that develop much more frequently in dogs than in cats. Breed-specific predispositions have been identified for both cancers. The development of novel diagnostics is underway and may aid in earlier diagnosis. Therapeutic approaches to HS and HSA depend on the stage of disease and may include surgery, radiation therapy, and chemotherapy. Such interventions improve outcome; however, aside from a small number of clinical circumstances, both diseases are considered largely incurable. Continued efforts toward the identification of driver mutations and subsequent druggable targets may lead to improvements in long-term prognosis.

Genome-wide DNA copy number analysis and targeted transcriptional analysis of canine histiocytic malignancies identifies diagnostic signatures and highlights disruption of spindle assembly complex

Canine histiocytic malignancies (HM) are rare across the general dog population, but overrepresented in certain breeds, such as Bernese mountain dog and flat-coated retriever. Accurate diagnosis relies on immunohistochemical staining to rule out histologically similar cancers with different prognoses and treatment strategies (e.g., lymphoma and hemangiosarcoma). HM are generally treatment refractory with overall survival of less than 6 months. A lack of understanding regarding the mechanisms of disease development and progression hinders development of novel therapeutics. While the study of human tumors can benefit veterinary medicine, the rarity of the suggested orthologous disease (dendritic cell sarcoma) precludes this. This study aims to improve the understanding of underlying disease mechanisms using genome-wide DNA copy number and gene expression analysis of spontaneous HM across several dog breeds. Extensive DNA copy number disruption was evident, with losses of segments of chromosomes 16 and 31 detected in 93% and 72% of tumors, respectively. Droplet digital PCR (ddPCR) evaluation of these regions in numerous cancer specimens effectively discriminated HM from other common round cell tumors, including lymphoma and hemangiosarcoma, resulting in a novel, rapid diagnostic aid for veterinary medicine. Transcriptional analysis demonstrated disruption of the spindle assembly complex, which is linked to genomic instability and reduced therapeutic impact in humans. A key signature detected was up-regulation of Matrix Metalloproteinase 9 (MMP9), supported by an immunohistochemistry-based assessment of MMP9 protein levels. Since MMP9 has been linked with rapid metastasis and tumor aggression in humans, the data in this study offer a possible mechanism of aggression in HM.

Rare myeloid sarcoma with KMT2A (MLL)-ELL fusion presenting as a vaginal wall mass

Backgroud

Myeloid sarcoma (MS) is a rare neoplasm of immature myeloid precursors that form tumor mass outside the bone marrow. The diagnosis of de novo MS can be challenging, particularly in patients with no prior history of hematologic malignancies or when MS involves unusual anatomic sites.

Case presentation

The patient was a 53-year-old woman with a history of uterine fibroids and vaginal bleeding for many years who presented with a vaginal wall mass. The tumor had histologic and phenotypic features of histiocytic sarcoma, however, overlapping with a possible extramedullary MS. Using a comprehensive genomic profiling, we were able to identify recurrent chromosomal aberrations associated with MS including a rare KMT2A-ELL fusion, losses of chromosomes 1p, 9, 10, 15, 18, and gain of chromosome 1q and mutations in FLT3 and PTPN11, and achived the final diagnosis of a de novo MS. The patient received standard treatment for acute myeloid leukemia regimen with stem cell transplantation and achieved complete remission.

Conclusion

Our case illustrates the clinical utility of comprehensive genomic profiling in assisting the diagnosis or differential diagnosis of challenging MS or histiocytic sarcoma cases, and in providing important information in tumor biology for appropriate clinical management.

Clinical significance of the two-base insertion mutation in the TP53 gene in canine histiocytic sarcoma

Canine histiocytic sarcoma (HS) is an aggressive tumor type originating from dendritic cells or macrophages. We previously reported high incidence of the two-base (AT) insertion mutation (insAT) in the tumor protein p53 (TP53) gene in dogs with HS, and the aim of this study was to investigate the clinical significance of insAT in canine HS. The present study established a sensitive digital PCR-based assay for detecting insAT and examined its associations with clinical variables and survival time. The mutation was detected in 26 of 64 dogs (41%), and the mean mutant allele frequency was 1.9% (range, 0.014-35%), indicating that not all tumor cells harbor insAT. The incidence of insAT was significantly higher in dogs with metastatic lesions than in those without metastatic lesions. However, the existence of insAT was not associated with survival time or response to chemotherapy with lomustine or nimustine. This study suggested that HS cells might acquire insAT in the TP53 gene during development of metastasis, but insAT was not a prognostic factor in canine HS. Further studies are needed to investigate the contribution of insAT to the development of metastatic lesions of canine HS.

Putative histiocytic sarcoma in redfin needlefish Strongylura notata (Beloniformes: Belonidae) in Florida, USA

Redfin needlefish Strongylura notata from Florida coastal waters were observed with unusual neoplastic lesions. Affected specimens were collected from 1 Atlantic estuary (Indian River Lagoon, prevalence = 0.32%, n = 5314) and 2 Gulf of Mexico estuaries (Tampa Bay, prevalence = 0.02%, n = 10762; Charlotte Harbor, prevalence = 0.02%, n = 5112) during routine fisheries-independent monitoring surveys conducted from 1999-2009. Grossly, each lesion manifested as a large (18-30 mm × 20-50 mm), raised (approximately 10 mm), white, creamy, or pinkish nodule on the flank, dorsal trunk, base of the pectoral fin, or head. Multiple small (<5 mm) nodules possessing poorly demarcated borders with neighboring tissues on the external jaw surface and at the base of the teeth were also observed. Histopathologically, neoplastic cells were found in the dermis, beneath the skeletal muscle, and in the soft tissue at the base of teeth of the premaxilla and the dentary jaw processes. Neoplastic cells usually had prominently invaded among the myosepta of the skeletal muscle. Neoplastic parenchymal cells had the basic characteristics of atypical, mononuclear, round, histiocytic cells with an eccentric, reniform nucleus and abundant cytoplasmic vacuolation, while some exhibited bizarre nuclear pleomorphism. Transmission electron microscopy revealed that neoplastic cells had a grooved nucleus and cytoplasmic organelles with rough endoplasmic reticulum, mitochondria, Golgi apparatus, and lysosomes. Neoplastic cells had possibly metastasized to liver, spleen, and kidney. Positive immunohistochemical staining with Ki67, p53, S-100, and CD163 support neoplastic features and a putative diagnosis of histiocytic sarcoma.

A case of recurrent histiocytic sarcoma with MAP2K1 pathogenic variant treated with the MEK inhibitor trametinib

Histiocytic sarcoma in advanced clinical stages is typically an aggressive neoplasm, with poor response to conventional chemotherapy. An 18-year-old male with refractory histiocytic sarcoma that had transformed from Rosai-Dorfman disease was admitted to our hospital. A pathogenic variant of MAP2K1 was detected by next-generation sequencing of tumor specimens. Affected regions showed excellent responses to the MEK inhibitor trametinib. It has been reported that RAS/MEK/ERK pathway is activated in many cases of histiocytic sarcoma. MEK inhibition may represent a useful treatment option in histiocytic sarcoma.

Primary histiocytic sarcoma of the central nervous system: a case report with platelet derived growth factor receptor mutation and PD-L1/PD-L2 expression and literature review

Background

Histiocytic sarcoma (HS) is an aggressive malignant neoplasm. HS in the central nervous system is exceptionally rare and associated with a poor prognosis. This report documents a case of primary HS of the central nervous system with treatment including surgery, radiotherapy, and chemotherapy.

Case presentation

Our patient was a 47 year old female presenting with progressive ataxia, headaches, imbalance, nausea, vomiting, and diplopia. MRI showed a heterogeneously enhancing lesion approximately 2.9 × 3.0 × 2.3 cm centered upon the cerebellar vermis with mild surrounding vasogenic edema and abnormal enhancement of multiple cranial nerves. The patient underwent surgical debulking, which revealed histiocytic sarcoma with grossly purulent drainage. Staging revealed diffuse leptomeningeal involvement, primarily involving the brain and lower thoracic and lumbar spine. She underwent adjuvant radiotherapy to the brain and lower spine and was started on high dose methotrexate. However, she experienced progressive disease in the cervical and thoracic spine as well as pulmonary involvement. Genomic sequencing of her tumor showed a mutation in the platelet-derived growth factor receptor A (p.V0681) which could be targeted with Dasatinib. However, she did not tolerate Dasatinib and she succumbed to progressive disseminated disease eight months from original diagnosis. Our pathologic evaluation also revealed expression of PD-L1 and PD-L2 by tumor cells raising the potential therapeutic role for immune checkpoint inhibition.

Conclusions

This case provides an example of effective CNS control with resection and moderate doses of radiation therapy. A review of the literature confirms aggressive multidisciplinary treatment is the most effective treatment against this disease. In addition, genomic sequencing may play an important role in determining new therapeutic options. However, CNS histiocytic sarcoma remains an aggressive disease with a propensity for early widespread dissemination and few long term survivors.

Histiocytic cell neoplasms involving the bone marrow: summary of the workshop cases submitted to the 18th Meeting of the European Association for Haematopathology (EAHP) organized by the European Bone Marrow Working Group, Basel 2016

The bone marrow is a preferential site for both reactive and neoplastic histiocytic proliferations. The differential diagnosis ranges from reactive histiocyte hyperplasia in systemic infections, vaccinations, storage diseases, post myeloablative therapy, due to increased cell turnover, and in hemophagocytic lymphohistiocytosis, through extranodal Rosai-Dorfman disease to neoplasms derived from histiocytes, including histiocytic sarcomas (HS), Langerhans cell histiocytoses (LCH), Erdheim-Chester disease (ECD), and disseminated juvenile xanthogranuloma (JXG). One of the most important recent developments in understanding the biology of histiocytic neoplasms and in contributing to diagnosis was the detection of recurrent mutations of genes of the Ras/Raf/MEK/ERK signaling pathway, in particular the BRAF^V600E mutation, in LCH and ECD. Here, we summarize clinical and pathological findings of 17 histiocytic neoplasms that were presented during the bone marrow symposium and workshop of the 18th European Association for Haematopathology (EAHP) meeting held in Basel, Switzerland, in 2016. A substantial proportion of these histiocytic neoplasms was combined with clonally related lymphoid (n = 2) or myeloid diseases (n = 5, all ECD). Based on the latter observation, we suggest excluding co-existent myeloid neoplasms at initial staging of elderly ECD patients. The recurrent nature of Ras/Raf/MEK/ERK signaling pathway mutations in histiocytic neoplasms was confirmed in 6 of the 17 workshop cases, illustrating their diagnostic significance and suggesting apotential target for tailored treatments.

Fas-ligand and caspase-3 positivity in three cases of histiocytic sarcoma: a different etiopathogenic pathway?

Histiocytic sarcoma (HS) is a rare malignant neoplasia of hematopoietic origin and unknown etiology. We studied three patients with histiocytic sarcoma reviewing the morphological and immunohistochemical aspects. We evaluated in particular, if apoptosis may be unbalanced in this disease. All cases have morphological and immunohistochemical features consistent with the diagnosis of histiocytic sarcoma. The markers CD163, CD68, vimentin, lysozyme, and S-100 were positive in all cases. Similarly, the three samples were positive for Fas-ligand and Caspase-3. It is well-known that neoplasms may induce increased levels of Fas-ligand with the blockade of the apoptosis process. In the context of HS, the increased Fas-ligand expression represents a new area for research. Indeed, it is linked to proinflammatory stimulus and, maybe with the association of an infection.

A novel canine histiocytic sarcoma cell line: initial characterization and utilization for drug screening studies

Background

Histiocytic sarcoma is a rare disorder in humans, however it is seen with appreciable frequency in certain breeds of dogs, such as Bernese mountain dog. The purpose of this study was to fully characterize a novel canine histiocytic sarcoma cell line, and utilize it as a tool to screen for potential therapeutic drugs.

Methods

The histiocytic sarcoma cell line was characterized by expression of cellular markers as determined by immunohistochemistry and flow cytometry techniques. The neoplastic cells were also evaluated for their capability of phagocytizing beads particles, and their potential to grow as xenograft in an immunodeficient mouse. We investigated the in vitro cytotoxic activity of a panel of thirteen compounds using the MTS proliferation assay. Inhibitory effects of different drugs were compared using one-way ANOVA, and multiple means were compared using Tukey’s test.

Results

Neoplastic cells expressed CD11c, CD14, CD18, CD45, CD172a, CD204, MHC I, and vimentin. Expression of MHC II was upregulated after exposure to LPS. Furthermore, the established cell line clearly demonstrated phagocytic activity similar to positive controls of macrophage cell line. The xenograft mouse developed a palpable subcutaneous soft tissue mass after 29 days of inoculation, which histologically resembled the primary neoplasm. Dasatinib, a tyrosine kinase pan-inhibitor, significantly inhibited the growth of the cells in vitro within a clinically achievable and tolerable plasma concentration. The inhibitory response to dasatinib was augmented when combined with doxorubicin.

Conclusions

In the present study we demonstrated that a novel canine histiocytic sarcoma cell line presents a valuable tool to evaluate novel treatment approaches. The neoplastic cell line favorably responded to dasatinib, which represents a promising anticancer strategy for the treatment of this malignancy in dogs and similar disorders in humans.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4132-0) contains supplementary material, which is available to authorized users.