Dendritic cell tumors associated with low-grade B-cell malignancies. Report of three cases

A case report of a blueberry muffin baby caused by congenital self-healing indeterminate cell histiocytosis

BACKGROUND

Blueberry muffin is a descriptive term for a neonate with multiple purpuric skin lesions. Many causes are known, amongst them life-threatening diseases like congenital infections or leukemia. Indeterminate cell histiocytosis (ICH) is an exceptionally rare cause of blueberry muffin rash. ICH is a histiocytic disorder which can be limited to the skin or can present with systemic involvement. A mutation that has been described in histiocytic disorders is a MAP2K1 mutation. In ICH, this mutation has previously been described in merely one case.

CASE PRESENTATION

A term male neonate was admitted to the neonatology ward directly after birth because of a blueberry muffin rash. ICH was diagnosed on skin biopsy. The lesions resolved spontaneously. The patient is currently 3 years old and has had no cutaneous lesions or systemic involvement so far. This disease course is similar to that of the Hashimoto-Pritzker variant of LCH.

CONCLUSIONS

ICH can manifest in neonates as resolving skin lesions. It is limited to the skin in most cases, but systemic development is possible. Therefore, it is essential to confirm the diagnosis with a biopsy before the lesions resolve and to monitor these patients closely with routine follow-up.

Indeterminate Dendritic Cell Tumor as Cutaneous Involvement of Chronic Myelomonocytic Leukemia Successfully Treated With Phototherapy

Indeterminate dendritic cell tumor (IDCT) is a rare disease composed of so-called indeterminate cells, a dendritic cell subset displaying histological and some ultrastructural and immunophenotypic features of Langerhans cells, but lacking Birbeck granules. We report a case of cutaneous IDCT occurring in a patient with chronic myelomonocytic leukemia (CMML) successfully treated with UV-A phototherapy. Next-generation sequencing studies of the CMML demonstrated mutations in TET2, ASXL1, and ZRS2 genes, also detected in the IDCT, demonstrating a clonal relationship between both tumors and confirming IDCT as a specific subtype in the spectrum of CMML-related cutaneous lesions.

Indeterminate Cell Histiocytosis Mimicking Rosacea

Indeterminate cell histiocytosis (ICH) is a rare proliferative disorder of histiocytes, which display morphologic and immunophenotypic characteristics of both Langerhans cell histiocytosis (LCH) and non-Langerhans cell histiocytosis (NLCH). We describe an unusual clinical presentation of ICH mimicking rosacea and provide a relevant review of the literature.

Indeterminate Cell Histiocytosis of the Spine: A Case Report

INTRODUCTION

Indeterminate cell histiocytosis is a rare neoplastic disease characterized by proliferation of dendritic cells that share morphologic and immunophenotypic features of Langerhans cells and non-Langerhans histiocytes. ICH lesions are typically restricted to the skin; however, there have been rare reports of extracutaneous and systemic involvement.

CASE PRESENTATION

We describe a case of a 13-year-old female presenting with complaints of worsening lower back pain for 1 year. CT and MRI of the lumbar spine demonstrated a well-defined bony, lytic, expansile lesion of the posterior and mid-endplate of the L4 vertebra with mass effect on the thecal sac. The patient underwent L3-L5 decompression and fusion with surgical excision of the vertebral body tumor. Microscopic examination of the lesion showed benign fibrohistiocytic proliferation with giant cells, and immunohistochemical staining revealed a phenotype consistent with indeterminate cell histiocytosis (S100+ CD1a+ langerin-).

DISCUSSION/CONCLUSION

ICH is an extraordinarily rare neoplastic disease of dendritic cells that has a poorly understood pathogenesis. This case expands the spectrum of potential ICH extracutaneous involvement to now include the spine, a location previously undocumented in the literature in the pediatric population.

Histiocytic Sarcoma: Review, Discussion of Transformation From B-Cell Lymphoma, and Differential Diagnosis

Context.—

Histiocytic sarcoma is a rare neoplasm of mature histiocytes with an aggressive clinical course that can arise de novo or from a low-grade B-cell lymphoma. In particular, chronic lymphocytic leukemia/small lymphocytic lymphoma is a very common malignancy in the Western hemisphere, and most cases of chronic lymphocytic leukemia/small lymphocytic lymphoma have an indolent course and behavior. However, 2% to 8% of chronic lymphocytic leukemia/small lymphocytic lymphoma cases transform. Histiocytic sarcomatous transformation is rare and portends poor prognosis.

Objective.—

To review the clinical features, morphology, and key points related to the differential diagnosis for histiocytic sarcoma. We discuss recent understanding of the biology underlying transformation.

Data Sources.—

University of Michigan case and review of pertinent literature about histiocytic sarcoma and morphologic differential diagnosis.

Conclusions.—

Histiocytic sarcoma is a rare histiocytic neoplasm that can arise as a result of transdifferentiation from low-grade B-cell lymphomas, and has a wide differential diagnosis including other histiocytic/dendritic cell neoplasms, myeloid neoplasms, lymphomas, melanoma, and carcinoma. However, some key morphologic and immunohistochemical features allow for accurate classification.

The t(14;18) translocation is absent from endothelial and follicular dendritic cells of follicular lymphoma (FL) and shows heterogeneous presence in preserved FL mantle zones

Background

The translocation t(14;18)(q32;q21) is the genetic hallmark of follicular lymphoma (FL) and can be observed in 85–90% of cases. Whether the translocation is restricted to cells with germinal center B-cell phenotype or can be observed in other cell types of the microenvironment remains debated. Of interest, cases of associated histiocytic and dendritic cell sarcomas arising in the background of FL have been shown to be clonally related and carry the t(14;18), suggesting a “transdifferentiation” of the malignant FL clone into a neoplasm of a different hematopoietic lineage.

Methods

We analyzed the presence of the t(14;18)(q32;q21) as a surrogate marker of the malignant clone in cells of the FL microenvironment using combined fluorescence immunophenotyping and interphase cytogenetics targeting the BCL2 gene locus. In addition to non-lymphoid cells in FL, we analysed FL with preserved IgD+ mantle zones and cases of in situ follicular neoplasia (ISFN) to investigate whether cells of non-germinal center B-cell phenotype are part of the malignant clone.

Results

Six (40%) of 15 manifest FL cases with preserved IgD+ mantle zones did not harbour the t(14;18)(q32;q21) translocation. In all t(14;18) + FL cases, follicular dendritic cells and endothelial cells lacked the t(14;18) translocation. 2/9 FL revealed t(14;18)- IgD+ mantle zone B-cells. In the seven ISFN cases, the t(14;18) translocation was strictly confined to germinal center cells.

Conclusions

The t(14;18) translocation in follicular lymphoma is limited to B-cells. The origin of IgD+ mantle cells is heterogeneous, in the majority of cases belonging to the neoplastic clone, whereas a minority of cases of manifest FL show nonneoplastic mantle zones, similar to ISFN.

Recurrent Indeterminate Dendritic Cell Tumor of the Skin

Indeterminate dendritic cell tumor (IDCT) is a dendritic cell tumor that displays histologic features similar to those of Langerhans cells. The origin of the indeterminate cells may represent precursors of Langerhans cells or skin dendritic cells. IDCT is extremely rare, and tumor progression and predictive factors are not well known. Here, we report a case of a 61-year-old man who presented with a papule on his back and was finally diagnosed with IDCT based on histology and immunohistochemistry. The tumor recurred three months after surgical excision.

Indeterminate dendritic cell neoplasm of the skin: A 2-case report and review of the literature

Indeterminate dendritic cell neoplasm (IDCN) is an exceedingly rare and mostly cutaneous histiocytosis, frequently associated with other hematopoietic malignancies. We report 2 cases of multilesional cutaneous IDCN. A 55-year-old male with no associated malignancy and complete response to ultraviolet phototherapy; and a 72-year-old male with chronic myelomonocytic leukemia (CMML). Both cases showed histiocytoid cytology, positivity for CD1a and no expression of langerin or BRAF^V600E . With our patients, the literature describes 79 cases of IDCNs, including 65 (82%) with only skin involvement, 7 cases (9%) with involvement of skin and a second site, 5 cases (6%) involving lymph nodes only, 1 splenic lesion and 1 systemic disease. Seventeen cases (22%) were associated with other hematopoietic malignancies, most commonly CMML (6 cases), follicular lymphoma (4 cases) and acute myeloid leukemia (3 cases). All IDCNs associated with myeloid malignancies were limited to the skin, while most cases associated with lymphoma were limited to lymph nodes. Reported responses of cutaneous lesions to ultraviolet phototherapy are encouraging, while systemic chemotherapy is appropriate for clinically aggressive cases and treatment of associated malignancies. Recognition of the clinico-morphologic spectrum of IDCNs should prevent misdiagnoses and prompt investigation of possible associated neoplasms.

Histiocytic and dendritic cell neoplasms: what have we learnt by studying 67 cases

Tumors derived from histiocytic and dendritic cells encompass a large and heterogeneous group of neoplastic and reactive conditions, and their diagnosis is challenging both for pathologists and clinicians. Diagnosis is based on morphological and phenotypical findings, but hybrid features are not uncommon. Furthermore, recent studies uncovered the molecular mechanisms driving some of these tumors, improving diagnostic adequacy, and providing the basis for effective therapeutic breakthroughs.Sixty-seven cases were submitted to the accessory cell and histiocytic neoplasms session at the European Association of Haematopathology/Society for Hematopathology workshop 2016 held in Basel, Switzerland. The cases included histiocytic sarcomas (HS), Langerhans cell tumors (LCT), Erdheim-Chester disease, interdigitating dendritic cell sarcomas (IDCS), indeterminate dendritic cell tumors (IND-DCT), follicular dendritic cell sarcomas, and blastic plasmacytoid dendritic cell neoplasms. Rosai-Dorfman disease and, more rare, conditions such as ALK-positive histiocytosis were also submitted. These cases illustrated classical and unexpected features at morphological, phenotypical, and molecular levels, providing a valuable compendium for pathologists confronting with these tumors.The paper summarizes the most notable features of every single group of diseases, with comments about the most challenging issues, in the attempt to provide practical indications for their recognition.

Generalized Indeterminate Cell Histiocytosis Presenting as Eroded Papules and Crusts

Indeterminate cell histiocytosis (ICH) is a very rare histiocytic disease. We reported a case of generalized ICH presenting as eroded papules and crusts, accompanied with intermittent fever, pulmonary disorder, lymphadenectasis in the mediastinum, and the retroperitoneum. The histopathology indicated a neoplasm that was composed of small nests of large cells with ample pale cytoplasm. Immunohistochemistry results and the absence of Birbeck granules led us to the diagnosis of ICH. Four months later, the patient died of anemia, ascites, and swelling of the limbs.

Primary Indeterminate Dendritic Cell Tumor of Skin Correlated to Mosquito Bite

Primary indeterminate dendritic cell tumor (IDCT) is an extremely neoplastic dendritic cell disorder. Little is known about its pathogenesis, etiology, and prognostic factors because of its rarity. Herein, we present a case report of a skin IDCT that arose in mosquito bite and discuss the correlation between hypersensitivity to mosquito bites and leukemia/lymphoma.A 28-year old man presented with multiple widespread cutaneous plaques and nodules 8 months after being bitten by a mosquito on his back. Dermatological examination revealed multiple skin-colored, well-demarcated plaques and nodules measuring approximately 0.5 to 1.8 cm in diameter all over the body. A biopsy of the skin lesion was taken. Morphologically, the dermis was effaced by round or polygonal cells with oval nuclei and abundant eosinophilic cytoplasm, arranged in nests and in some areas in a sheet-like pattern. The tumor cells were positive for CD68, CD1a, and S-100, whereas negative for Langerin and lack Birbeck granules ultrastructurally. A diagnosis of IDCT was made. No treatment was given. The patient was alive with spontaneous disease regression after 17 months of follow-up.IDCT is an extremely rare disease and may be associated with mosquito bite.

Spontaneous regression of interdigitating dendritic sarcoma in a patient with concurrent small lymphocytic lymphoma

Interdigitating dendritic cell sarcoma (IDCS) is a rare tumour; only seven cases of IDCS associated with chronic lymphocytic leucaemia/small lymphocytic lymphoma (CLL/SLL) have been reported. We present the case of a 60-year-old man who presented with fevers, night sweats and significant unintentional weight loss. Investigations led to a diagnosis of synchronous SLL and IDCS. Subsequent fluorodeoxyglucose (FDG) positron emission tomography CT (PET-CT) imaging revealed an unusual clinical course with spontaneously resolving highly metabolic lesions. After 42 months of follow-up, the patient remains free of clinical symptoms and evidence of IDCS.

Dendritic cell and histiocytic neoplasms: biology, diagnosis, and treatment

BACKGROUND

Dendritic and histiocytic cell neoplasms are rare malignancies that make up less than 1% of all neoplasms arising in lymph nodes or soft tissues. These disorders have distinctive disease biology, clinical presentations, pathology, and unique treatment options. Morphology and immunohistochemistry evaluation by a hematopathologist remains key for differentiating between these neoplasms. In this review, we describe tumor biology, clinical features, pathology, and treatment of follicular dendritic cell sarcoma, interdigitating dendritic cell sarcoma, indeterminate dendritic cell sarcoma, histiocytic sarcoma, fibroblastic reticular cell tumors, and disseminated juvenile xanthogranuloma.

METHODS

A literature search for articles published between 1990 and 2013 was undertaken. Articles are reviewed and salient findings are systematically described.

RESULTS

Patients with dendritic cell and histiocytic neoplasms have distinct but variable clinical presentations; however, because many tumors have recently been recognized, their true incidence is uncertain. Although the clinical features can present in many organs, most occur in the lymph nodes or skin. Most cases are unifocal and solitary presentations have good prognoses with surgical resection. The role of adjuvant therapy in these disorders remains unclear. In cases with disseminated disease, prognosis is poor and data on treatment options are limited, although chemotherapy and referral to a tertiary care center should be considered. Excisional biopsy is the preferred method of specimen collection for tissue diagnosis, and immunohistochemistry is the most important diagnostic method for differentiating these disorders from other entities.

CONCLUSIONS

Dendritic cell and histiocytic cell neoplasms are rare hematological disorders with variable clinical presentations and prognoses. Immunohistochemistry remains important for diagnosis. Larger pooled analyses or clinical trials are needed to better understand optimal treatment options in these rare disorders. Whenever possible, patients should be referred to a tertiary care center for disease management.

Clinicopathologic characteristics and outcomes of histiocytic and dendritic cell neoplasms: the moffitt cancer center experience over the last twenty five years

Neoplasms of histiocytic and dendritic cells are rare disorders of the lymph node and soft tissues. Because of this rarity, the corresponding biology, prognosis and terminologies are still being better defined and hence historically, these disorders pose clinical and diagnostic challenges. These disorders include Langerhans cell histiocytosis (LCH), histiocytic sarcoma (HS), follicular dendritic cell sarcoma (FDCS), interdigtating cell sarcoma (IDCS), indeterminate cell sarcoma (INDCS), and fibroblastic reticular cell tumors (FRCT). In order to gain a better understanding of the biology, diagnosis, and treatment in these rare disorders we reviewed our cases of these neoplasms over the last twenty five years and the pertinent literature in each of these rare neoplasms. Cases of histiocytic and dendritic cell neoplasms diagnosed between 1989–2014 were identified using our institutional database. Thirty two cases were included in this analysis and were comprised of the following: Langerhans cell histiocytosis (20/32), histiocytic sarcoma (6/32), follicular dendritic cell sarcoma (2/32), interdigitating dendritic cell sarcoma (2/32), indeterminate dendritic cell sarcoma (1/32), and fibroblastic reticular cell tumor (1/32). Median overall survival was not reached in cases with LCH and showed 52 months in cases with HS, 12 months in cases with FDCS, 58 months in cases with IDCS, 13 months in the case of INDCS, and 51 months in the case of FRCT. The majority of patients had surgical resection as initial treatment (n = 18). Five patients had recurrent disease. We conclude that histiocytic and dendritic cell neoplasms are very rare and perplexing disorders that should be diagnosed with a combination of judicious morphology review and a battery of immunohistochemistry to rule out mimics such as carcinoma, lymphoma, neuroendocrine tumors and to better sub-classify these difficult to diagnose lesions. The mainstay of treatment for localized disease remains surgical resection and the role of adjuvant therapy is unclear. In patients with multiple areas of involvement, treatment at tertiary care centers with multimodality treatment is likely needed. Accurate subset diagnosis will contribute to better data as well as treatment outcomes analysis of these rare disorders of adult patients in the future.

Clonal Relationships Between Malignant Lymphomas and Histiocytic/Dendritic Cell Tumors

Tumors of histiocytic or dendritic cell origin appear to occur with increased frequency in patients with lymphoma. Recent molecular data have demonstrated clonal relationships between the lymphoma and the histiocytic/dendritic cell tumor in some of these cases. Clinical, pathologic, and experimental data suggest that this phenomenon probably represents transdifferentiation of the lymphoma clone to a histiocytic/dendritic cell lineage in most cases. Awareness of this entity is necessary to prompt comparative molecular studies in appropriate cases.

The genetics of interdigitating dendritic cell sarcoma share some changes with Langerhans cell histiocytosis in select cases

Histiocytic disorders have been noted to have evidence of transdifferentiation; examples of cases with combinations of different lineages have been shown. In our index case, we identified interdigitating dendritic cell (IDC) differentiation in a case of Langerhans cell histiocytosis (LCH). Little is currently known about the genetics of IDC sarcoma (IDCS) because they are exceedingly rare. Using array comparative genomic hybridization (aCGH), we evaluated 4 cases of IDCS and compared them with our index case, as well as genetic abnormalities previously found in LCH. Four cases of paraffin-embedded samples of IDCS and 1 case of LCH with IDC differentiation were evaluated using aCGH. Array CGH results showed no abnormalities in a case of LCH with interdigitating cell differentiation. In 3 of 4 cases of IDCS, genetic abnormalities were identified; 1 case had no identifiable abnormalities. Interdigitating dendritic cell sarcoma case 1 had gains of 3q and 13q; IDCS case 2 had trisomy 12; IDCS case 3 had deletions of 7p, 12p, 16p, 18q, 19q, and 22q; and IDCS case 4 had no detectable abnormalities. Our index case, LCH with IDC differentiation, showed no abnormalities by aCGH. A number of LCH cases do not have detectable genetic abnormalities. In contrast, 3 of 4 cases of IDCS evaluated had identifiable abnormalities by aCGH. Furthermore, 2 of these shared abnormalities, albeit of large genetic regions, with published abnormalities seen in LCH. No recurrent abnormalities were identified in the IDCS cases. However, the possibility of a relationship between IDCS and LCH cannot be entirely excluded by these results.

Langerhans Cell Sarcoma Arising from Chronic Lymphocytic Lymphoma/Small Lymphocytic Leukemia: Lineage Analysis and BRAF V600E Mutation Study

Background:

the phenomenon that histiocytic/dendritic cell sarcomas may be transformed from lymphoproliferative diseases is dubbed ‘transdifferentiation’. Langerhans cell sarcoma (LCS) transdifferentiated from chronic lymphocytic leukemia/small cell lymphoma (CLL/SLL) is extremely rare. The underlying mechanisms of LCS tumorogenesis and its transdifferentiation from CLL/SLL are largely unknown.

Aims:

the authors strive to further characterize LCS, to understand the potential molecular changes in LCS and the underlying mechanisms of CLL/SLL transformation to LCS.

Materials and Methods:

a progressively enlarging right inguinal lymph node from a 68-year-old female patient with a history of CLL was biopsied and submitted for flow cytometry analysis, routine hematoxylin, and eosin (H and E) stain and immunohistochemical study. Furthermore, clonality study (fluorescent in situ hybridization (FISH) analysis with a CLL panel probes) and BRAF V600E mutation study (pyrosequencing and immunostain) were performed.

Results:

two different neoplasms, LCS and CLL/SLL, were discovered to occur simultaneously in the same lymph node. These two entities were shown to be clonally related. More importantly, for the first time, BRAF V600E mutation was detected in LCS.

Conclusions:

LCS can be transdifferentiated from CLL/SLL and BRAF V600E mutation may provide the foundation for alternative therapy of LCS.

Dendritic cell sarcoma: a pooled analysis including 462 cases with presentation of our case series

Dendritic cell tumors are extremely rare and current knowledge on these tumors is limited. The characteristics of three dendritic cell sarcoma subtypes and their optimal treatment approaches are not fully clarified. We aimed to make a systematic review of the literature and enrich the current data with five new cases. Pooled analysis of 462 reported cases revealed that the tumor had no age, gender or racial predilection. Our analysis suggests that the young age, advanced stage, intraabdominal involvement and unfavorable histological features (i.e. large tumor size, absence of lymphoplasmacytic infiltration, coagulative necrosis, high mitotic count) may predict poor prognosis. Subtypes of this tumor have different clinical behaviors with interdigitating dendritic cell sarcoma being the most aggressive form. In general, surgery is the most effective treatment modality and adjuvant radiotherapy has no significant effect on overall survival of patients. The role of chemotherapy for the management of advanced disease is controversial.

Interdigitating dendritic cell sarcoma presenting simultaneously with acute myelomonocytic leukemia: report of a rare case and literature review

Interdigitating dendritic cell sarcoma (IDCS) is an extremely rare tumor derived from interdigitating dendritic cells. We report the first case of a 64-year-old Chinese woman who was diagnosed with simultaneous IDCS and acute myelomonocytic leukemia (AML-M4). The patient had undergone chemotherapy for breast cancer 6 years previously. Based on the laboratory results, both the IDCS and the AML-M4 in this patient were determined to be of myelogenous origination. Furthermore, a review of 62 IDCS cases (Medline database, key word: IDCS) reported to date revealed that as many as 17 % of the patients had malignant disease and received radiotherapy and/or chemotherapy prior to developing IDCS, and that this group of patients showed worse prognosis compared with counterparts. The patient in the present report showed poor response to four cycles of sequential chemotherapy, and died 6 months after the initial diagnosis.

Clonally related histiocytic/dendritic cell sarcoma and chronic lymphocytic leukemia/small lymphocytic lymphoma: a study of seven cases

Histiocytic and interdigitating dendritic cell sarcomas are rare tumors originating from bone marrow-derived myeloid stem cells. Recent studies have shown evidence of cross-lineage transdifferentiation of B cells in follicular lymphoma to histiocytic and dendritic cell sarcomas. In this study, we report the morphologic, molecular and cytogenetic analysis of seven cases of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) associated with histiocytic and dendritic cell sarcomas. All seven patients were elderly males (median age 71 years). The B-cell neoplasms preceded the development of the histiocytic and dendritic cell sarcomas in six of seven patients, and one patient had both tumors diagnosed at the same time. The tumors included four interdigitating dendritic cell sarcomas: one Langerhans cell sarcoma, one histiocytic sarcoma and one immature neoplasm with evidence of histiocytic origin. Laser-capture microdissection and PCR analysis showed identical clonal immunoglobulin gene rearrangements in the two phenotypically distinct components in all cases. There was a preferential usage of IGHV4-39 by the V-D-J gene rearrangement. By fluorescence in situ hybridization (FISH) analysis, two cases showed deletion 17p in both components, whereas four cases had normal cytogenetic findings by FISH in the CLL/SLL cells, but acquired cytogenetic abnormalities in the corresponding histiocytic and dendritic tumors. Chromosome 17p abnormalities were the most common cytogenetic abnormality detected in the sarcomas, seen in five of six cases studied. Compared with the CLL/SLL cells, the histiocytic/dendritic cells were largely negative for PAX5, but showed strong expression of PU.1 and variable and weak expression of CEBPβ. Our study provides evidence for transdifferentiation of CLL/SLL B cells to tumors of dendritic and less often histiocytic lineage, and suggests that secondary genetic events may play a role in this phenomenon.

Interdigitating dendritic cell sarcoma following adult liver transplantation: case report and literature review

Interdigitating dendritic cell sarcoma is an extremely rare neoplasm derived from professional antigen presenting cells. We report an unusual case of such a tumor occurring in a 61-year-old woman who had undergone orthotopic liver transplantation for stage IVA2 primary hepatocellular carcinoma with a raised preoperative α-fetoprotein level, followed by tacrolimus-based immunosuppressive therapy. During her subsequent management, the tacrolimus blood levels ranged from 7.9 ng/mL to 16.1 ng/mL. Physical examination revealed bilateral neck and left axillary lymphadenopathy. No evidence of either chronic hepatitis B virus or Epstein-Barr virus could be detected in serum. An excisional biopsy of a right neck lymph node was performed. Microscopically, the normal architecture was diffusely effaced by a proliferation of spindled to ovoid cells arrayed in a fascicular, ill-defined whorled pattern and small lymphocytes were admixed in varying numbers with the tumor cells. Immunohistochemical studies showed that the tumor cells were positive for S100 protein, vimentin and CD68. Based on these findings, the case was diagnosed as an interdigitating dendritic cell sarcoma. The patient unfortunately had no response to 2 cycles of CHOP chemotherapy (cyclophosphamide, doxorubicin, vincristine, and prednisone), and died of wide spread disease 6 months after the original biopsy. We propose that tacrolimus-based immunosuppression was associated with the development of interdigitating dendritic cell sarcoma after liver transplantation in this case.

Clinicopathologic features of histiocytic lesions following ALL, with a review of the literature

We describe the clinicopathologic features of 15 patients who had histiocytic lesions that followed acute lymphoblastic leukemia (ALL). Twenty-one separate histiocytic lesions were evaluated that covered a wide spectrum, some conforming to the usual categories of juvenile xanthogranulomas (5), Langerhans' cell histiocytosis (1), Langerhans' cell sarcoma (4), Rosai-Dorfman disease (1), and histiocytic sarcoma (4). Most were atypical for the category by histology, phenotype, or abnormally high turnover rate. Seven low-grade lesions defied easy categorization and were characterized only as "atypical histiocytic lesion" following ALL. For those evaluated, the molecular signature of the prior leukemia was present in the histiocytic lesion. In 3 of 15 patients, the leukemia and histiocytic lesion shared immunoglobulin H or monoclonal TCR gene rearrangements and, in 4 of 15 patients, clonal identity was documented by fluorescence in situ hybridization. Four patients died of progressive disease, 3 of whom had histiocytic sarcoma and 1 who had an atypical lesion. One patient died of recurrent ALL. The other 10 patients are alive, 7 after recurrences and treatment with surgery and/or chemotherapy. The post-ALL lesions are more aggressive than their native counterparts, but despite the demonstration of the presence of the leukemia signature in 7 of 15 patients, the prognosis is generally favorable, except for patients with histiocytic sarcoma. It remains unclear whether the histiocytic lesions arise as a line from the original ALL or whether transdifferentiation is involved.

Transformation of chronic lymphocytic leukemia/small lymphocytic lymphoma to interdigitating dendritic cell sarcoma: evidence for transdifferentiation of the lymphoma clone

Interdigitating dendritic cell sarcoma (IDCS) is a rare tumor derived from interdigitating dendritic cells. Three cases of IDCS associated with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) have been described, but no clonal relationship between the 2 neoplasms was demonstrated. We present a detailed case analysis of a CLL/SLL with metachronous IDCS and demonstrate that these 2 neoplasms are clonally related. The IDCS and CLL cells had trisomy 12 and identical monoclonal immunoglobulin heavy chain gene rearrangements. Analysis of transcription factors with a role in myeloid differentiation demonstrated PU.1 up-regulation and C/EBPalpha down-regulation in IDCS compared with CLL. High-density array comparative genomic hybridization also identified gains in part of chromosome 16q in IDCS. Our study demonstrates for the first time clonal transformation of CLL/SLL into IDCS. This phenomenon may be triggered by alterations in lineage-determining transcription programs, which result in transdifferentiation, coupled with additional oncogenic stimuli caused by chromosomal imbalances.

Transformation of B cell lymphoma to histiocytic sarcoma: somatic mutations of PAX-5 gene with loss of expression cannot explain transdifferentiation

Transdifferentiation of B cell lymphoma of germinal center cell origin to histiocytic sarcoma has recently been described but is a rare occurrence. The cause for loss of B cell differentiation in these lymphomas is unknown. We investigated whether somatic hypermutation of the PAX-5 gene, a transcription factor that is important for maintaining B cell identity and is frequently mutated in B cell lymphomas of germinal center cell origin, might be a cause for loss of PAX-5 expression and thus B cell phenotype. However, no somatic hypermutation of the PAX-5 gene was detected in the two cases we studied. The molecular basis for transdifferentiation of B cell lymphoma to histiocytic sarcoma remains therefore unresolved.

Histiocytic/dendritic cell sarcoma arising from follicular lymphoma involving the bone: a case report and review of literature

Histiocytic/dendritic cell sarcomas arising from follicular lymphoma are very rare and poorly understood lesions. We describe a case, which is unique in that it presented with a hipbone lesion simultaneously with axillary lymphadenopathy. Biopsy of the axillary lymph node showed a low-grade follicular lymphoma. The hipbone lesion was comprised two cell populations, one representing diffuse large B cell lymphoma and the other a histiocytic/dendritic sarcoma. The cells of all three lesions contained an IGH/BCL2 rearrangement, suggesting that both diffuse large B cell lymphoma and histiocytic/dendritic sarcoma differentiation developed from the same low grade precursor (follicular lymphoma). This case illustrates that sarcomatous transdifferentiation of follicular lymphoma can be an unpredictable local phenomenon and that it can occur extra nodally in the bone marrow. It may also occur concurrently with the progression of follicular lymphoma to a diffuse large B cell lymphoma.

Clonally related follicular lymphomas and histiocytic/dendritic cell sarcomas: evidence for transdifferentiation of the follicular lymphoma clone

Rare cases of histiocytic and dendritic cell (H/DC) neoplasms have been reported in patients with follicular lymphoma (FL), but the biologic relationship between the 2 neoplasms is unknown. We studied 8 patients with both FL and H/DC neoplasms using immunohistochemistry, fluorescence in situ hybridization (FISH) for t(14;18), and polymerase chain reaction (PCR)/sequencing of BCL2 and IGH rearrangements. There were 5 men and 3 women (median age, 59 years). All cases of FL were positive for t(14;18). The H/DC tumors included 7 histiocytic sarcomas, 5 of which showed evidence of dendritic differentiation, and 1 interdigitating cell sarcoma. Five H/DC tumors were metachronous, following FL by 2 months to 12 years; tumors were synchronous in 3. All 8 H/DC tumors showed presence of the t(14;18) either by FISH, or in 2 cases by PCR with the major breakpoint region (MBR) probe. PCR and sequencing identified identical IGH gene rearrangements or BCL2 gene breakpoints in all patients tested. All H/DC tumors lacked PAX5, and up-regulation of CEBPbeta and PU.1 was seen in all cases tested. These results provide evidence for a common clonal origin of FL and H/DC neoplasms when occurring in the same patient, and suggest that lineage plasticity may occur in mature lymphoid neoplasms.

Dendritic cell sarcoma: an analytic overview of the literature and presentation of original five cases

Interdigitating and follicular dendritic cell sarcoma (DCS) are very rare diseases, with approximately 184 cases being reported thus far, and their best treatment modality is still on debate. This is a review of all the cases of dendritic cell sarcoma reported from 1981 until April 2006. This review is enriched with the original contribution of five cases occurred at our Institution from 1994 to 2006. The review of the literature pointed out that radical surgery alone was curative in approximately two thirds of these cases, the relapsing rate in patients who received adjuvant treatments being higher than 30%. We pinpoint new five cases of dendritic cell sarcoma (three FDCS and two IDCS). Both the analytic revision of the literature and our data suggest that localized DCS may be effectively treated by radical surgery and do not support the use of adjuvant treatments after radical excision.

Indeterminate cell histiocytosis in association with later occurrence of acute myeloblastic leukaemia

Indeterminate cell histiocytosis (ICH) is a proliferation of indeterminate CD1a+, CD68+, S100+ and CD207- dermal dendritic cells. We describe a 39-year-old man who developed diffuse ICH and, 6 years later, acute myeloblastic leukaemia (AML). He was treated with cyclophosphamide, etoposide and vinblastine until 2003. In August 2004, he presented dyspnoea, hyperpyrexia and infiltration of the lung parenchyma, compatible with an AML invasion, and died after a course of induction chemotherapy. Cytomorphology and immunophenotype analyses suggested an ICH clonal evolution. The leukaemogenic role of etoposide is discussed. ICH has previously been reported in association with B-cell malignancy, but only one case has shown systemic progression.

Acquired mucosal indeterminate cell histiocytoma

Indeterminate cell histiocytosis is an exceptional and controversial entity with variable clinical, histopathologic or immunohistochemical findings, sharing morphologic and immunophenotypic features from both Langerhans and non-Langerhans cell histiocytoses. Neoplastic cells express S-100 and CD1a antigens, but lack Birbeck granules. It has been reported in both adults and children, as solitary or multiple cutaneous lesions with rare extracutaneous involvement. We describe a 12-year-old boy with an indeterminate cell histiocytosis manifesting as a solitary verrucous papule on the mucosa of the glans penis. The morphologic features and diagnostic criteria of cutaneous indeterminate cell histiocytic proliferations are reviewed. The possible relationship between indeterminate cell and Langerhans cell histiocytoses is discussed.

Synchronous Interdigitating Dendritic Cell Sarcoma and B-Cell Small Lymphocytic Lymphoma in a Lymph Node

A gradually enlarging axillary mass in a 79-year-old man was excised. The specimen was processed for light microscopy, immunohistochemical studies, and electron microscopy; gene rearrangement studies were also performed. A diagnosis of an interdigitating dendritic cell tumor of the lymph node and a B-cell small lymphocytic lymphoma occurring in the same anatomic location was made. We found that although rare cases of interdigitating dendritic cell tumor with an associated secondary malignancy have been described in the literature, to our knowledge, this is the first report of interdigitating dendritic cell tumor and synchronous neoplasm diagnosed at the same site. A possible relationship between the 2 disorders is also discussed.

Indeterminate cell histiocytosis: fact or fiction?

Indeterminate cell histiocytosis is a rare disorder, in which the predominant cells have the characteristics of both Langerhans cells and macrophages. We, in this study, describe 18 patients and compare them with those previously published. Most patients were adults with either solitary or multiple red-brown papules or nodules. While most lesions were confined to the skin, both conjunctival and bony involvement was seen. Histologically, the lesions showed patterns resembling those described for xanthogranulomas, with predominantly oncocytic (nine patients), spindled (five patients), scalloped (two patients) or vacuolated (two patients) macrophages. The accompanying infiltrate was mainly lymphocytic, although eosinophils and occasionally plasma cells were seen. All lesions were positive for macrophage markers, such as KP1 (CD68) and Ki-M1p, as well as for S-100 protein and showed variable reactivity for CD1a. No Birbeck granules were seen ultrastructurally in one patient. Some patients shared features with sinus histiocytosis with massive lymphadenopathy. It is unclear whether this disorder is a separate entity or represents various macrophage disorders identified at various time points in the inflammatory response. Ratzinger G, Burgdorf WHC, Metze D, Zelger BG, Zelger B. Indeterminate cell histiocytosis: fact or fiction? A clinicopathological series of 18 patients.

Interdigitating dendritic cell tumor with breast and cervical lymph-node involvement: a case report and review of the literature

Interdigitating dendritic cell tumor (IDCT) is an extremely rare malignancy. It occurs primarily in lymph nodes, but extranodal involvement has also been reported. A 38-year-old woman with IDCT with breast and cervical lymph-node involvement is reported in this paper. To our knowledge, this is the first case of IDCT originating from the breast. In the breast and lymph node, the tumor displayed diffuse sheets, fascicles and storiform growth pattern. It was composed of oval to spindle cells with pale to eosinophilic cytoplasm, ill-defined cell outlines, oval nuclei with vesicular chromatin and prominent eosinophilic nucleoli. Mitotic activity was three per ten high-power fields. The neoplastic cells were intermingled with small mature lymphocytes and plasma cells. Immunohistochemical studies showed that the tumor cells were strongly and diffusely positive for vimentin, CD68, S-100 protein, CD45/leukocyte common antigen and fascin and focally positive for lysozyme, alpha-1 antitrypsin and CD4. Ki-67 labeling index was 10%. The patient was treated with combined therapeutic approaches, including surgery, radiotherapy and chemotherapy. IDCT has the potential for an aggressive clinical course. However, 32 months after the initial diagnosis, the patient is still alive and being followed with a stable tumor burden.

Follicular lymphoma of the skin and superficial soft tissues associated with a prominent follicular dendritic cell proliferation: an unusual pattern which may represent a diagnostic pitfall

We describe two elderly patients with follicular lymphoma (FL) involving the skin and superficial soft tissues, with a striking proliferation of follicular dendritic cells (FDC). In addition, one patient had bone marrow involvement by FL. Histopathologically, the most remarkable feature in both cases seen at low magnification was a striking pallor of the constituent cells, which were arranged in fascicles, whorls, and round islands. The majority of the cells had the typical cytologic features of FDCs. They were intimately intermingled with centroblasts and centrocytes. A large amount of the clear cytoplasm and the pale nuclei of FDCs, which predominated in the tumors, caused the striking overall pallor of the lesions. Small reactive lymphocytes were scattered between the fascicles. A vague follicular growth pattern was seen only focally. The mantle zones were markedly reduced or absent so that the follicles were seen lying unseparated. The close intermixture of the FDCs and the germinal center cells was responsible for the FDCs appearing to be decorated with B-associated marker, and the germinal center cells seemed to be stained to some degree with FDC-markers. The tumor bulk demonstrated a diffuse and strong reaction with CD10, CD20, CD21, CD35, and stained weakly with CD79a. Fascin and CD23 showed only a weak and focal staining pattern. Bcl-2 decorated large centroblasts and small reactive T-cells. The tumor bulk was negative for actin, EMA, cytokeratins, vimentin, desmin, and factor XIIIa. The proliferative index was rather low; MIB-1 mainly decorated large centroblasts. No monoclonal rearrangement of IgH genes was detected. Epstein-Barr virus was not identified. Electron microscopy revealed typical features of FDCs intermingled with germinal center cells. Such cases may represent a diagnostic pitfall, as FDC overgrowth can mask FL and give the neoplasm the appearance of FDC sarcoma/tumor. We believe that, in both cases, the FDC proliferation had a reactive character.

Interdigitating dendritic cell sarcoma: a report of four paediatric cases and review of the literature

AIMS

To report a series of four paediatric cases of interdigitating dendritic cell sarcoma (IDCS) and add to the known extranodal sites of occurrence for this tumour. Neoplasms derived from interdigitating dendritic cells are rare, with only 33 cases being reported in the literature (Medline search). These tumours usually occur in lymph nodes in the adult population.

METHODS AND RESULTS

The patients were a 10-year-old girl with a large soft tissue mass bulging into the left chest, a 12-year-old girl with a right paraspinal mass, a 21-month-old boy with generalized lymphadenopathy and hepatosplenomegaly and a 6-year-old girl with a large bladder mass. Paraffin blocks and haematoxylin and eosin slides were available in all cases. In addition, immunohistochemistry and electron microscopy were performed. A diagnosis of IDCS was made in all cases.

CONCLUSION

The diagnosis of IDCS can rarely be entertained on clinical information alone. Microscopically, there is a wide spectrum of features. Thus, immunohistochemistry and electron microscopy are crucial in making the diagnosis. The differential diagnosis includes inflammatory pseudotumour, follicular dendritic cell sarcoma, true histiocytic lymphoma, malignant Langerhans cell histiocytosis, anaplastic large-cell lymphoma, melanoma, and a range of sarcomas. IDCS displays aggressive behaviour and approximately half of the patients die of the disease.