Systemic Histiocytosis (Langerhans Cell Histiocytosis, Erdheim-Chester Disease, Destombes-Rosai-Dorfman Disease): from Oncogenic Mutations to Inflammatory Disorders

Craniofacial Langerhans Cell Histiocytosis Successfully Treated Through Intralesional Injection of Triamcinolone Acetonide: A Retrospective Study

Treatment options for single-system Langerhans cell histiocytosis (LCH) range from observation to chemotherapy. Among these options, corticosteroid injection is appealing due to the feasibility, preservation of structure and function as well as the low complication rate. Therefore, this study aimed to investigate the effectiveness of intralesional injection of triamcinolone acetonide (TA) for the treatment of craniofacial LCH and present a typical case. 11 patients diagnosed with LCH of the jaws who received intralesional injection of TA at Hospital of Stomatology, Sun Yat-sen University from April 2014 to May 2021 were involved. Clinicopathologic data were collected and analyzed. The 11 subjects included 7 males and 4 females (mean age 14.6±16.9 y). Most lesions were located in the mandible (n=9, 81.8%). The effective rate of intralesional injection of TA was 90.9%. The average initial dosage and average accumulative dosage were 33.2±21.0 and 99.5±88.7 mg, respectively. The mean time needed for complete ossification of the lesion was 12.5±8.2 months. The mean follow-up time was 20±13.4 months. Although the effective rate was similar between children and adults (100% versus 75%, P=0.364), the initial dosage, accumulative dosage, number of injections, and time needed for complete ossification of the lesion were all lower in children (P<0.05). In conclusion, intralesional injection of TA is a suitable treatment option for craniofacial LCH, especially in children. Studies that incorporate a larger patient cohort should be conducted to verify the current findings.

Temporal bone Langerhans cell histiocytosis with uterine cervix involvement and cutaneous Erdheim-Chester disease

With fewer than 40 documented cases, temporal bone Langerhans cell histiocytosis (LCH) is exceptionally rare in adults. We present a case of temporal bone and uterine cervix LCH in an adult with concurrent cutaneous Erdheim-Chester disease. A woman in her 50s presented with several months of unilateral right aural fullness, otalgia, otorrhoea and tinnitus, unresponsive to antibiotics and aural irrigation. CT of the temporal bone revealed right mastoid destruction, prompting further investigation. Histology obtained from mastoid exploration confirmed LCH. Initial management included radiotherapy, followed by methotrexate and later, cytarabine. Disease monitoring was conducted withPositron Emision Tomography-CT. Due to its rarity, LCH is often initially misdiagnosed. Clinicians should remain vigilant for LCH in patients presenting with unresolved otological symptoms that deviate from the expected clinical course. Swift communication between relevant medical teams is essential for rapid diagnosis and optimal management of potential multisystem LCH when symptoms present in different areas.

MR Imaging of Tumors and Tumor-Like Conditions of the Hip

The hip joint is home to a diverse range of neoplasms, as well as many pseudo lesions, including post-traumatic, infectious, and degenerative processes. Through careful evaluation of the clinical context, location, and imaging features, these entities can be distinguished, enabling accurate and efficient diagnosis. While not exhaustive, this article reviews a selection of benign, malignant, and non-neoplastic lesions affecting the hip bones, cartilage, and soft tissues, focusing on their notable imaging and pathologic features.

Beyond BRAFV600E: Investigating the Clinical and Genetic Spectrum of Langerhans Cell Histiocytosis in Children

BACKGROUND

Langerhans cell histiocytosis (LCH) is the most prevalent histiocytic disorder in pediatric populations, with a highly heterogeneous clinical presentation. Currently, the correlation between clinical phenotypes and molecular alterations in childhood LCH, besides the BRAFV600E mutation, has not been sufficiently studied.

METHODS

This study presented data on 33 pediatric LCH patients treated at our center who exhibited various molecular alterations other than the BRAFV600E mutation. Additionally, we comprehensively reviewed pediatric LCH cases with non-BRAFV600E molecular alterations reported from January 2010 to August 2024.

RESULTS

A total of 309 pediatric LCH patients with molecular alterations beyond BRAFV600E were enrolled in the study, among whom 33 were from our center. In these LCH cases, 49 kinds of MAP2K1 mutations, 31 kinds of BRAF mutations, and 4 kinds of ARAF mutations were found. At our center, two patients with multisystem LCH with risk organ involvement, both with BRAFN486_P490del mutation, showed poor response to induction chemotherapy for 6 weeks. Among the 303 LCH patients with MAP2K1 or other BRAF alterations, patients with the MAP2K1 mutation had a higher prevalence of single-system bone involvement (SS-bone) than patients carrying the BRAF mutation (p = 0.0072). Within the MAP2K1 group, exon 3 mutations exhibited a stronger association with SS-bone than exon 2 mutations (p = 0.042). Additionally, patients with the BRAF exon 15 mutation and MAP2K1 exon 2 mutation had higher rates of LCH onset before age 3 compared with patients carrying the BRAF exon 12 mutation and MAP2K1 exon 3 mutation (p = 0.037; p = 0.0015). Patients carrying the BRAF mutation in exon 15 had higher rates of liver involvement compared with patients carrying the exon 12 (p = 0.042).

CONCLUSIONS

Pediatric LCH patients often carry recurrent somatic MAP2K1 and BRAF mutations, which are associated with clinical manifestations.

Orbital masses as a rare presentation of Rosai-Dorfman disease: Clinicopathologic characterization of five cases

Rosai-Dorfman disease (RDD) is a rare, non-Langerhans cell histiocytosis. Most cases present with marked, non-tender lymphadenopathy due to the proliferation of atypical histiocytes. A minority of cases involves extranodal sites and can present as bone lesions, skin rashes, pulmonary nodules, and rarely orbital masses. Orbital involvement in RDD is rare and may infrequently present as an isolated tumor mass without lymphadenopathy. This study aims to better characterize this uncommon presentation of this rare disease. Five cases of orbital RDD were identified from the last 18 years and the clinical characteristics of each case were compared with histopathological findings. Three men and two women ages 12-36 presented with complaints of eye swelling and/or vision changes. One patient had a history of neurofibromatosis type I and inflammatory pseudotumors while the other four had no signs of systemic disease or other sites of extranodal involvement at the time of presentation. Masses ranged in size from 1.0 cm to 3.5 cm and primarily involved the superior orbit. Resected lesions all displayed characteristic findings of admixed atypical histiocytes, lymphocytes, and plasma cells with a fibrotic background. Emperipolesis was seen in all cases. Immunostaining for S100 and CD68 was diffusely positive in the histiocyte population. Clinical follow-up was obtained for 4 of 5 patients: all four were disease-free at 1 to 15 years after resection. RDD should be considered in the differential for patients with orbital masses, even in the absence of lymphadenopathy or signs of systemic disease.

Common progenitor origin for Rosai-Dorfman disease and clear cell sarcoma

Histiocytic neoplasms (HNs) in adults have been reported to be associated with a high prevalence of coexisting haematological and solid malignancies. While a proportion of coexisting HNs and haematological malignancies share identical genetic alterations, the genetic association between HNs and solid malignancies has scarcely been reported. We report a case of Rosai-Dorfman disease (RDD) complicated by coexisting clear cell sarcoma (CCS). RDD is a rare HN. CCS is an ultrarare soft tissue sarcoma with a poor prognosis. Mutation analysis with whole-exome sequencing revealed six shared somatic alterations including NRAS p.G12S and TP53 c.559+1G>A in both the RDD and CCS tissue. This is the first evidence of a clonal relationship between RDD and solid malignancies using mutational analysis. We hypothesise that neural crest cells, which originate in CCS, are likely the common cells of origin for RDD and CCS. This case helps to unravel the underlying clinicopathological mechanisms of increased association of solid malignancies in HNs. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Co-occurrence of Erdheim-Chester disease and clonally evolving acute myeloid leukemia with FLT3-ITD and PTPN11 mutations

Erdheim-Chester disease (ECD) is a rare histiocytosis that tends to co-exist with other myeloid malignancies. Here, we use genetic and transcriptomic sequencing to delineate a case of co-occurring BRAFV600E-mutated ECD and acute myeloid leukemia (AML), followed by AML remission and relapse. The AML relapse involved the extinction of clones with KMT2A-AFDN and FLT3-ITD, and the predominance of PTPN11-mutated subclones with distinct transcriptomic features. This case report has highlighted the screening for other myeloid malignancies at the diagnosis of ECD and the clinical significance of PTPN11-mutated AML subclones that require meticulous monitoring.

Erdheim‑Chester disease of multisystem involvement with delayed diagnosis: A case report and literature review

Erdheim-Chester disease (ECD) is a rare tumor of histiocytic origin, characterized by foamy or lipid-laden histiocytes mixed or surrounded by fibrosis that infiltrate multiple organs. Misdiagnosis is common due to the diversity of clinical presentations. The present study reported a case of ECD with the involvements of bone, cardiac, aorta and retroperitoneum. The patient had no obvious clinical symptoms and no noteworthy foamy histiocytes or Touton giant cells were found on pathological examination, delaying the diagnosis. The patient was a young male found to have pericardial effusion on physical examination, and computed tomography (CT) revealed soft tissue infiltrates in the retroperitoneum and around the aorta. A mediastinal biopsy revealed fibrous connective tissue with small-vessel hyperplasia and acute-chronic inflammatory cell infiltration. The initial diagnosis was retroperitoneal fibrosis (RPF), and hormonal and tamoxifen treatments were administered. The patient presented with oliguria, eyelid edema and fever four years later. A repeat CT revealed an increase in the extent of tissue infiltration and pericardial effusion compared with the previous CT. Subsequent cardiac magnetic resonance imaging revealed massive thickening in the form of fibrotic tissue infiltrating the heart and surrounding thoracic and abdominal aorta. Single photon emission CT revealed multiple areas of increased bone metabolism, particularly symmetrical involvement of the long bones of both lower extremities. A biopsy of the perirenal tissue revealed fibrous tissue and a small number of lymphocytes and macrophages [typical foamy histiocytes observed via x200 magnification and hematoxylin-eosin (HE) staining, no presence of xanthogranuloma or Touton giant cells]. After a comprehensive evaluation and ruling out other diseases, the diagnosis of ECD was determined. The prognosis of this disease is poor; early diagnosis is critical and requires accurate judgment by clinicians. Biopsies of all involved sites and refinement of genetic tests to guide treatment, if possible, are both necessary.

Erdheim-Chester Disease: Investigating the Correlation between Targeted Treatment Therapy and Disease Outcomes

A retrospective analysis of 20 adult patients with histopathological and clinical diagnoses of ECD was conducted at a single institution over a twenty-year period (2002-2022). Clinical responses were compared on the basis of treatments rendered, which included chemotherapy, immunotherapy, systemic corticosteroids, surgery and radiation, or targeted agents, referring to any small molecular inhibitors. Treatment response evaluation varied by the anatomic site(s) of disease, the extent of disease at diagnosis, and the imaging modality employed. In this analysis, patients were treated with a combination of targeted agents, myelosuppressive therapies, and radiation at various points in their disease courses. Of these, the most common treatment modality rendered was targeted therapy, employed in 11 of 20 patients. Partial responses or better were observed in 15 of 20 patients. Rates of stable disease trended towards being more frequent with targeted therapy versus conventional therapy but did not reach significance (p = 0.2967). Complete response rates trended towards being more common with conventional therapy than molecular (p = 0.5) but were equivocal overall. Trends of peripheral blood absolute monocytes with relation to disease activity were reviewed as recent literature implied that monocyte levels surrounding disease progression were of potential prognostic significance in histiocytic diseases. Amongst the patients who progressed at any point during their treatment course, absolute monocyte count (in K/µL) was identified at the closest available timepoint prior to or following disease progression and at the lowest value (nadir) following re-institution of therapy prior to any additional agent(s) being employed. There was no statistically significant difference in either of these monocyte values nor in disease outcomes with respect to treatments rendered within our cohort. However, our cohort consists of a heterogenous population of patients with ECD with data that highlights several trends over a longitudinal period, spanning the advent of targeted therapy. Significant differences are anticipated in ongoing analyses.

The role of 2-[18F]FDG PET/CT in Erdheim-Chester disease

OBJECTIVE

To analyze the body distribution of Erdheim-Chester disease (ECD) and determine the utility of 2-[18 F]FDG PET/CT compared to other imaging techniques. Additionally, to assess the aggressiveness and extent of the disease based on the presence/absence of the BRAFV600E mutation.

MATERIALS AND METHODS

The 2-[18F]FDG-PET/CT scans of all patients diagnosed with ECD between 2008 and 2021 were reviewed, including 19 patients. The affected territories were classified as detectable by PET/CT or detectable only by other imaging techniques (bone scintigraphy, contrast-enhanced CT, or MRI). Descriptive analysis and correlation of the BRAF mutation with the affected organs and maximum SUV were performed using the Student's t-test.

RESULTS

Out of the 19 patients (14 males; mean age 60.3 years), 11 had the BRAFV600E mutation. A total of 127 territories (64 organ-systems) affected were identified using different imaging modalities, of which 112 were detected by PET/CT, and an additional 15 territories were solely identified by cerebral and cardiac MRI. The presence of BRAFV600E mutation was associated with greater organ involvement (p < 0.05) without differences in SUVmax (p > 0.05).

CONCLUSION

2-[18F]FDG PET/CT is a highly effective diagnostic tool in patients with ECD, detecting the majority of affected territories. MRI was the only imaging modality with additional findings in territories showing high physiological uptake of 2-[18F]FDG (cerebral and cardiac). The presence of the BRAFV600E mutation correlated with a higher extent of the disease.

Dermoscopy and reflectance confocal microscopy finding of different anatomic sites of Langerhans cell histiocytosis

BACKGROUND

Recognizing Langerhans cell histiocytosis (LCH) might be a challenge due to its rarity. Reflectance confocal microscopy (RCM) and dermoscopy were emergent promising non-invasive technique as auxiliary tools in diagnosis of different skin conditions. However, the RCM and dermoscopic features of LCH had been less investigated. To reveal the common RCM and dermoscopic features of LCH.

MATERIALS AND METHODS

Forty cases of LCH were retrospectively analyzed according to age, locations, clinical, RCM, and dermoscopic features from September 2016 to December 2022. To reveal the differences and common in clinical, RCM, and dermoscopic features that occur in different anatomic location.

RESULTS

In the study, sites of predilection include the trunk 31/40 (77.5%), extremity 21/40 (52.5%), face 14/40 (35%), scalp 11/40 (27.5%), vulvar 4/40 (10%), and nail 2/40 (5%). All LCHs had the common RCM features. There were significant differences in clinical and dermoscopic features for age and lesion anatomic site. The common dermoscopic features for scalp, face, trunk, and extremity were the erythematous scaly rash, purplish-red globules or patches, scar-like streaks with ectatic vessels. While the features for nail LCH were purpuric striae, onycholysis and purulent scaly rash, and the erosive erythematous plaque and purulent scaly rash for vulvar LCH. The common RCM features of all LCH showed a focal highly reflective dense image in the surface keratin layer, epidermis architectural disarray, obscuration of dermo-epidermal junction, numerous polygonal, large, medium reflective, short dendrites cells in the epidermis, and dermis. All LCH involving the vulvar and nail did not manifest skin lesions.

CONCLUSION

RCM and dermoscopy showed promising value for diagnosis and differentiation of LCH.

Investigating the correlation between small molecular inhibitor utilization, peripheral blood monocytes, and treatment outcomes in Rosai Dorfman disease

Rosai Dorfman disease (RDD) is a non-Langerhans cell histiocytic neoplasm characterized by sinus histiocytosis with variable emperipolesis. There is a limited understanding of the factors that contribute to disease progression. Traditional management of RDD consists of local therapies (resection, radiation) for localized disease and myelosuppression for systemic disease; targeted medications have also recently been introduced into clinical practice as an additional therapeutic modality. The goals of this study are to compare the impact of targeted therapies to conventional management of RDD and identify trends in laboratory data that may provide insight into disease progression. A retrospective analysis was conducted at a single institution over a 20-year period in 35 adult patients with histopathologic evidence of RDD without confounding secondary malignancies. Clinical data points included laboratory evaluation, molecular diagnostics, imaging, and therapies rendered. Binary data was utilized for statistical analysis and comparison of outcomes by treatment type and utilization of targeted agents. Evaluation of treatment response varied based on anatomic disease sites and baseline imaging modality. To standardize the radiographic analysis, we included PERCIST (if PET was utilized) or RECIST assessments (in the cases of CT or MR imaging). Conventional therapies rendered included local treatment (surgery, radiation, intralesional injections), systemic corticosteroids, immunotherapy, and chemotherapy while targeted agents included only small molecule inhibitors. In this analysis, primary disease was identified in cutaneous, osseous, and CNS structures (17, 11, and 6/35 patients respectively). Management consisted of surgery (12/35 patients), steroid and myelosuppressive therapies (9/35 each), immunotherapy (5/35), and targeted molecular agents (5/35). In evaluating outcomes, the proportion of partial responses was substantially higher in recipients of molecular as compared to conventional therapy (4/5 patients compared to 6/29) while complete responses were more common in the conventional therapy cohort (12/29 compared to 1/5). Lastly, an evaluation of peripheral blood absolute monocytes in all patients who had progressed on therapy identified a significant decrease in pre-progression values as compared to values following therapy re-institution (averages of 0.70 and 0.27 K/µL, respectively; p = 0.0002, 95% CI 0.652-0.2360). Larger-scale studies are needed to further evaluate the relevance of the monocyte trends that were identified in terms of their relationship to disease status. This study is the largest analysis of Rosai Dorfman disease, that we are aware of, from a single institution. In this cohort, the utilization of small molecule inhibitors corresponded to a greater increase in partial responses than conventional therapies, although the opposite effect has been observed in complete responses. This finding can be attributed to the recent introduction of targeted agents and shorter follow-up. We anticipate higher complete response rates with the use of small molecule in ongoing analyses over a longer follow-up period. The recognition of relative monocyte elevation prior to disease progression is an intriguing and to our knowledge, novel finding in the field of Rosai Dorfman disease. Future studies aimed at elucidating the implications of this trend are in progress.

Solitary Langerhans cell histiocytosis of the sternum in a 21-year-old woman

Children are more likely to develop Langerhans cell histiocytosis (LCH), a rare disorder with an unknown cause. LCH often invades skeletal systems, while it has occasionally been seen in the sternum or ribs. The best course of treatment for single-site, skeletal LCH is yet unknown. We present an instance of sternal LCH with adult onset. By fusing and reconstructing chest computed tomography, it was possible to determine the extent of surrounding soft tissue invasion. Because LCH is so uncommon, it could be challenging to recall when we see a sternal lesion. Adult Patients who arrive with anterior chest discomfort and an osteolytic sternal lesion should include LCH on their differential diagnosis list.

Langerhans Cell Histiocytosis Showed Intense Uptake of 68 Ga-FAPI

ABSTRACT

A 23-year-old man was recently diagnosed with Langerhans cell histiocytosis (LCH). 68 Ga-FAPI PET/CT showed multiple lesions with intense FAPI uptake in the axial and appendicular skeleton with lytic or mixed bone destruction, consistent with osseous lesions of LCH. FAPI-avid foci around the right atrium and inferior vena cava, as well as micronodules and thin-walled cysts in the lungs, were also noted, possibly also involvement of LCH. This case suggested that 68 Ga-FAPI PET/CT may have the potential to be applied in evaluation of LCH.

The value of 18F-FDG PET/CT in the systemic evaluation of patients with Rosai-Dorfman disease: a retrospective study and literature review

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare form of non-Langerhans cell histiocytic disease. The aim of this study was to review the characteristics of RDD using 18F-FDG PET/CT and determine its efficacy in the disease management.

RESULTS

A total of 28 RDD patients underwent 33 18F-FDG PET/CT scans for systematic assessment and follow-up. The common involved sites included the lymph nodes (17, 60.7%), upper respiratory tract (11, 39.3%), and skin (9, 32.1%). Five patients had more lesions detected in PET/CT images than in CT and/or MRI, including inapparent nodules (n = 5) and bone destruction (n = 3). After thorough treatment evaluation using PET/CT, the treatment strategies of 14 patients (14/16, 87.5%) were changed. Five patients underwent PET/CT twice during follow-up and the SUVs were significantly decreased (15.3 ± 3.4 vs. 4.4 ± 1.0, p = 0.02), which demonstrated disease improvement.

CONCLUSIONS

18F-FDG PET/CT contributed to displaying the holistic characteristics of RDD, in particular during initial assessment, treatment strategy adjustment, or efficacy evaluation, and could compensate for some disadvantages of CT and MRI images.

Multisystem ALK-positive histiocytosis: a multi-case study and literature review

BACKGROUND

Anaplastic lymphoma kinase (ALK)-positive histiocytosis, a novel rare histiocytic proliferation, was first described in 2008; it occurs in early infancy with liver and hematopoietic involvement. The spectrum was subsequently broadened to include localized diseases in older children and young adults. However, its full clinicopathological features and molecular lineage have not been fully elucidated.

RESULTS

Here, we report four cases of multisystem ALK-positive histiocytosis without hematopoietic involvement. Clinically, three patients were adults aged between 32 and 51 years. Two patients', whose main manifestations were intracranial mass and numerous micronodules in the thoracoabdominal cavity organs and skin papules respectively, had a partial response to ALK inhibitors after surgery. One patient presented with mediastinal neoplasm without surgical treatment, and progressive disease occurred after two years of ALK inhibitor therapy. The fourth patient was a 17-month-old male with a large intracranial mass and presented with a poor response to ALK inhibitor and chemoradiotherapy; he died eight months after surgery. Pathologically, the histiocytes were large, with abundant eosinophilic cytoplasm, and mixed with variable numbers of foamy cells and Touton giant cells. Interstitial fibrosis was also observed. Histiocytes were positive for macrophage markers (CD68 and CD163) and ALK. KIF5B-ALK fusions were detected in two cases, EML4-ALK in one, and both DCTN1-ALK and VRK2-ALK fusions were detected in one case.

CONCLUSIONS

We observed that ALK inhibitors present robust and durable responses in adult patients but a poor response in young children with central nervous system involvement. There is no consensus on the optimal treatment regimen and long-term prognosis requires further observation. Moreover, every unusual histiocytic proliferative lesion, especially unresectable and multisystem involvement, should be routinely tested for ALK immunohistochemical staining to identify this rare disease.

Sympatho-Vagal Dysfunction in Systemic Sclerosis: A Follow-Up Study

Systemic sclerosis (SSc) patients often present cardiovascular autonomic dysfunction, which is associated with the risk of arrhythmic complications and mortality. However, little is known regarding the progression of cardiac autonomic impairment over time. We aimed to evaluate the cardiac autonomic modulation among SSc with limited cutaneous (lcSSc), diffuse cutaneous (dcSSc) subset, and age-matched healthy control (HC) at baseline (t0) and five-year follow-up (t1). In this follow-up study, ECG was recorded at t0 and t1 in twenty-four SSc patients (dcSSc; n = 11 and lcSSc; n = 13) and 11 HC. The heart rate variability (HRV) analysis was conducted. The spectral analysis identified two oscillatory components, low frequency (LF) and high frequency (HF), and the sympatho-vagal balance was assessed by the LF/HF ratio. The LF/HF increased (p = 0.03), and HF reduced at t1 compared to t0 in dcSSc (p = 0.03), which did not occur in the lcSSc and HC groups. Otherwise, both lcSSc and dcSSc groups presented augmented LF/HF at t0 and t1 compared to HC (p < 0.01). In conclusion, a worsening of cardiac autonomic dysfunction is related to the dcSSc subset, in which a more extent of skin fibrosis and internal organs fibrosis is present.

Rosai-Dorfman Disease between Proliferation and Neoplasia

Rosai-Dorfman disease (RDD) is a rare myeloproliferative disorder of histiocytes with a broad spectrum of clinical manifestations and peculiar morphologic features (accumulation of histiocytes with emperipolesis). Typically, the patient with RDD shows bilateral painless, massive cervical lymphadenopathy associated with B symptoms. Approximately 43% of patients presented with extranodal involvement. According to the 2016 revised histiocytosis classification, RDD belongs to the R group, including familial and sporadic form (classical nodal, extranodal, unclassified, or RDD associated with neoplasia or immune disease). Sporadic RDD is often self-limited. Most RDD needs only local therapies. Nevertheless, a small subpopulation of patients may be refractory to conventional therapy and die of the disease. Recent studies consider RDD a clonal neoplastic process, as approximately 1/3 of these patients harbor gene mutations involving the MAPK/ERK pathway, e.g., NRAS, KRAS, MAP2K1, and, rarely, the BRAF mutation. In addition to typical histiocytic markers (S100/fascin/CD68/CD163, etc.), recent studies show that the histiocytes in RDD also express BCL-1 and OCT2, which might be important in pathogenesis. Additionally, the heterozygous germline mutation involving the FAS gene TNFRSF6 is identified in some RDD patients with an autoimmune lymphoproliferative syndrome type Ia. SLC29A3 germline mutation is associated with familial or Faisalabad histiocytosis and H syndrome.

Molecular and oral manifestations of langerhans cell histiocytosis preceding acute myeloid leukemia

Background

Langerhans cell histiocytosis (LCH) is a heterogeneous neoplastic disorder that is rarely seen in patients aged 60 years and older. It is reported that elderly patients with LCH have a higher chance of having malignancies. In the oral cavity, patients with LCH can present with mucosal ulcers and extensive osteolysis, making it difficult for clinicians to make a proper diagnosis.

Case presentation

We reported an 82-year-old Chinese woman with oral symptoms as the first presentation of LCH, and eventually developed acute myeloid leukemia (AML). She suffered diffuse ulcers involving the entire gingival mucosa and the left half hard palate, and had lost several teeth. Genomic DNA sequencing of the cells from LCH revealed multiple mutations in TET2, BRAF, SRSF2, NRAS, MAP2K4 and so on. The patient declined the BRAF^V600E inhibitor (Vemurafenib). Although a dramatic improvement of the oral ulcers was achieved after symptomatic treatment, the patient developed acute myeloid leukemia (AML) and died.

Conclusions

This report presented the diagnostic difficulties of LCH with oral manifestations and highlighted the importance of radiological assessments and laboratory tests. Moreover, many of the mutations detected in our LCH patient are frequently seen in AML, suggesting that AML and LCH cells in this patient share the same origin.

Ultrasonographic analysis of Langerhans cell histiocytosis in children: a report of 55 cases

OBJECTIVE

To explore the value of ultrasonography in the diagnosis and treatment of Langerhans cell histiocytosis (LCH) in children.

METHOD

The clinical and imaging features of 55 children with pathologically confirmed LCH were retrospectively analyzed.

RESULTS

Thirteen patients had bone LCH and 42 had multisystem LCH. Among the 13 cases of bone LCH, 8 cases involving the skull and 2 involving the scapula were characterized by osteolytic bone destruction, 1 case involving the clavicle and 1 involving the iliac bone showed multiple irregular bone destruction, and 1 case involving the tibia showed local hypoechoic cortical bone. Soft tissue echo filling was present in the local areas of bone destruction. Among the 42 cases of multisystem LCH, 33 involved the bone, 35 showed an enlarged liver, 15 involved the spleen, 2 involved the pancreas, 3 involved the lung, 3 involved the thymus, and 21 affected the lymph nodes in different regions.

CONCLUSIONS

Ultrasonography of the flat bones in children with LCH mainly showed punched-out osteolytic bone destruction. Long bone lesions were characterized by fan shell changes in the endosteum of long bones, and some also showed bone destruction. Multisystem LCH can affect almost any organ. Ultrasonography is important for early diagnosis.

FDG PET/CT in Mixed Langerhans Cell Histiocytosis and Erdheim-Chester Disease

ABSTRACT

The histiocytoses arise from hematopoietic bone marrow stem cells or monocytes. They range from limited to disseminated disease. We report a 31-year-old woman with multisystem Langerhans cell histiocytosis (LCH). The recognition that pericardial disease was rare in LCH prompted review of the initial limited biopsies, which helped establish a second diagnosis of Erdheim-Chester disease. The increasing recognition of mixed histiocytoses requires searching for Erdheim-Chester disease when a patient is diagnosed with LCH and vice versa. FDG PET/CT can help establish the diagnosis or suggest mixed disease based on the organs involved.

The Systolic Pulmonary Arterial Pressure Liaises Impaired Cardiac Autonomic Control to Pro-inflammatory Status in Systemic Sclerosis Patients

The current study was undertaken to test the hypothesis that systemic sclerosis (SSc) patients with higher systolic pulmonary arterial pressures (PAPs) present a blunted cardiac autonomic modulation and a pro-inflammatory profile. Thirty-nine SSc patients were enrolled (mean age 57 ± 11 years). ECG and respiration were recorded in the supine (SUP) position and during the active standing (ORT). Heart rate variability (HRV) analysis was performed on samples of 300 beats. The symbolic analysis identified three patterns, 0V%, (sympathetic) and 2UV% and 2LV%, (vagal). The %ΔORT was calculated from the differences between HRV in ORT and SUP, normalized (%) by the HRV values at rest. The PAPs was obtained non-invasively through echocardiography. For the inter-group analysis, participants were allocated in groups with higher (+PAPs ≥ median) and lower PAPs (–PAPs < median) values. At rest, the cardiac sympathetic modulation (represented by 0V%) was positively correlated with PAPs, while parasympathetic modulation (represented by 2LV%) was negatively correlated with PAPs. The dynamic response to ORT (represented by Δ0V% and Δ2LV%), sympathetic and parasympathetic were negatively and positively correlated with PAPs, respectively. The +PAPs group presented a higher inflammatory status and a blunted cardiac autonomic response to ORT (↓Δ0V% and ↑Δ2LV%) compared to the –PAPs group. These findings suggest an interplay among cardiac autonomic control, inflammatory status, and cardiopulmonary mechanics that should be considered for the assessment, monitoring, and treatment of SSc patients.

Diagnostic utility of flow cytometry in identifying histiocytic sarcoma-A case report

Histiocytic sarcoma (HS) is a malignant neoplasm of hematopoietic origin. It is an exceedingly rare and aggressive malignancy commonly seen in adults. Diagnosis is difficult owing to lack of specific clinical manifestations with the absence of precursor lesions or causative agents. Hence, it primarily relies on histopathological morphology combined with immunohistochemistry, which is time-consuming, hence resulting in delayed treatment. However, diagnostic utility of flow cytometry is not well established in this. We report a case of a 45-year-old man who presented with right axillary lymphadenopathy for 1 month. FNAC was performed on the axillary lymph node, which showed large, atypical lymphoid/histiocyte-like cells. On flow cytometry, these cells were CD64+, CD11c+, and CD45+ suggesting histiocytic sarcoma. Similar morphology was seen on incisional biopsy. On immunohistochemistry, the cells were negative for B and T cell markers, PAX5, EMA, CK, ALK, and CD1a and expressed CD68, S100, and CD11c. A diagnosis of histiocytic sarcoma was made. Hence, flow cytometry can be a highly effective and powerful tool for the early detection of HS and can help in prompt treatment, given its aggressive clinical course and low survival interval.

Cyclin D1 expression and molecular genetic findings in periocular histiocytoses and neoplasms of macrophage-dendritic cell lineage

PURPOSE

Frequent activating mutations in the mitogen-activated protein kinase (MAPK) pathway genes have been identified in histiocytoses. MAPK signaling consistently upregulates Cyclin D1. The goal of this study was to determine whether Cyclin D1 expression by immunohistochemistry is a useful diagnostic marker for periocular histiocytoses and to further characterize their genetic basis.

DESIGN

Retrospective observational case series.

METHODS

Pathology records were searched for all patients with histiocytoses diagnosed between 1995-2020. Eleven histiocyte-rich inflammatory lesions and 10 xanthelasma served as controls. Cyclin D1 immunohistochemistry was performed on all tissues. A subset of histiocytoses was evaluated by next-generation sequencing (NGS) and droplet digital PCR (ddPCR).

RESULTS

There were 36 patients, 15 (42%) males and 21 (58%) females, with histiocytoses: 9 (25%) juvenile xanthogranuloma, 8 (22%) adult-onset asthma and periocular xanthogranuloma, 7 (19%) Langerhans cell histiocytosis, 5 (14%) Rosai-Dorfman disease, 5 (14%) xanthogranuloma not otherwise specified, 1 (3%) Erdheim-Chester disease, and 1 (3%) histiocytic sarcoma. Moderate-to-strong nuclear Cyclin D1 expression was present in ≥50% of lesional cells in histiocytoses (23/36, 64%), significantly more when compared to histiocyte-rich inflammatory lesions (0/11, 0%, P<.001) and xanthelasma (0/10, 0%, P<.001). Cyclin D1 was expressed in <10% of lesional cells in all 11 histiocyte-rich inflammatory lesions (P<.001) and all 10 xanthelasma lesions (P<.001). MAPK pathway gene mutations were detected in 12 of 14 (86%) histiocytoses successfully assayed by NGS and/or ddPCR.

CONCLUSIONS

Our study confirms that the Cyclin D1 immunohistochemical stain is a useful diagnostic marker for periocular histiocytoses, correlating with underlying mutations in MAPK pathway genes.

18F-FDG PET/MR Assessment of Pediatric Langerhans Cell Histiocytosis

Introduction

Langerhans cell histiocytosis (LCH) is a histiocytic proliferative disease without a well-understood etiology. The aim of our study is to summarize the imaging features of PET/MR in children with LCH and to explore its diagnostic role in LCH.

Methods

Retrospective analysis was performed of the pretreatment PET/MR imaging data of 15 children with LCH. Comparison of ADC values was done between lesions and normal tissues.

Results

Of the fifteen patients enrolled, five had single-organ or single-system involvement, and ten had multiple-system involvement. Nine patients had varying degrees of bone destruction and increased FDG uptake, whereas thickening and deviation of the pituitary stalk and disappearance of the normal high-signal intensity of T1WI in the neurohypophysis were observed in the pituitary gland in six of them. Splenomegaly with diffuse increased FDG uptake or a normal spleen with increased FDG uptake was found in four cases, liver in three, multiple lymph node enlargement in three, pulmonary lesions in three, and increased metabolism in medullary cavity in two cases. Additionally, two cases involved the skin. Hypermetabolic nodules were detected in muscle in one case, thyroid involvement in one case, and a mediastinal lesion in one case.

Conclusion

PET/MR can show well the distribution of the organs, systems, and lesions involved in LCH and is of considerable significance in the systemic evaluation of LCH.

Rosai-Dorfman disease in the central nervous system with two isolated lesions originated from a single clone: a case report

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare, benign, idiopathic non-Langerhans cell histiocytosis. Cases of RDD in the CNS are extremely rare but lethal. RDD is thought to represent a reactive process. Recent studies proposed a subset of RDD cases that had a clonal nature. However, its clone origin is poorly understood.

CASE PRESENTATION

We present a rare case of RDD in the CNS with two isolated lesions. These two lesions were removed successively after two operations. No seizure nor recurrence appears to date (2 years follow-up). Morphological and immunohistochemical profiles of these two lesions support the diagnosis of RDD. Based on the whole-exome sequencing (WES) data, we found the larger lesion has a higher tumor mutational burden (TMB) and more driver gene mutations than the smaller lesion. We also found seven common truncal mutations in these two lesions, raising the possibility that they might stem from the same ancestor clone.

CONCLUSIONS

Overall, this is the first report about clonal evolution of RDD in the CNS with two isolated lesions. Our findings contribute to the pathology of RDD, and support the notion that a subset of cases with RDD is a clonal histiocytic disorder driven by genetic alterations.

Urinary involvement in Erdheim-Chester disease: computed tomography imaging findings

PURPOSE

To describe the urological manifestations of Erdheim-Chester disease (ECD) and their computed tomography (CT) findings.

METHODS

We retrospectively reviewed 48 patients diagnosed with ECD at Peking Union Medical College Hospital from January 2014 to January 2020. Twenty-four patients exhibited urological manifestations. Their CT findings, including appearances of the involved area (e.g., perirenal space, renal sinus, ureters, renal arteries, and adrenal glands), occurrence rate of ECD involvement in each area, signal enhancement pattern after CT contrast agent administration, disease progression, and causes of hydronephrosis were discussed.

RESULTS

In 24 patients with evidence of ECD urological involvement, the most common manifestation was perirenal infiltration, appearing as "hairy kidney" on unenhanced CT scans and moderate signal enhancement on enhanced CT scans (17/24, 70.8%). Other manifestations included renal sinus infiltration (16/24, 66.7%), proximal ureter involvement (14, 58.3%), renal artery sheath (10, 41.7%), hydronephrosis (14, 58.3%), and adrenal glands involvement (8, 33.3%). The histiocytic infiltrate was mostly bilateral, starting from the perirenal space and spreading to the renal sinus and ureters. Hydronephrosis was usually associated with infiltration of ureters.

CONCLUSION

Kidneys are the most common visceral organs affected by ECD. CT scanning is not only advantageous in early diagnosis, but also critical for designing the treatment regime for patients with ECD.

Indolent renal involvement with BRAFV600E mutation: Erdheim-Chester, a rare disease with a wide spectrum of clinical manifestations

We present the case of a patient with three-year indolent bilateral ureteral and perirenal masses. Clinical presentation, radiological context, and histopathological findings with detection of BRAF V600E mutation confirmed the diagnosis of Erdheim-Chester disease (ECD). A review of current knowledge regarding diagnosis, clinical assessment, management, and treatment of ECD is also presented.

Oncogene-induced maladaptive activation of trained immunity in the pathogenesis and treatment of Erdheim-Chester disease

Trained immunity (TI) is a pro-inflammatory program induced in monocyte/macrophages upon sensing of specific pathogens and characterized by immunometabolic and epigenetic changes enhancing cytokine production. Maladaptive activation of TI (i.e., in the absence of infection) might result in detrimental inflammation and disease development; however, the exact role and extent of inappropriate activation of TI in the pathogenesis of human diseases is undetermined. Here, we reveal oncogene-induced, maladaptive induction of TI in the pathogenesis of a human inflammatory myeloid neoplasm (Erdheim-Chester disease, ECD, characterized by the BRAFV600E oncogenic mutation in monocyte/macrophages and excess cytokine production). Mechanistically, myeloid cells expressing BRAFV600E exhibit all molecular features of TI: activation of the AKT/mTOR signaling axis; increased glycolysis, glutaminolysis, and cholesterol synthesis; epigenetic changes on promoters of genes encoding cytokines; and enhanced cytokine production leading to hyper-inflammatory responses. In ECD patients, effective therapeutic strategies contrast this maladaptive TI phenotype; in addition, pharmacologic inhibition of immunometabolic changes underlying TI (i.e., glycolysis) effectively dampens cytokine production by myeloid cells. This study reveals the deleterious potential of inappropriate activation of TI in the pathogenesis of human inflammatory myeloid neoplasms, and the opportunity for inhibition of TI in conditions characterized by maladaptive myeloid-driven inflammation.

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.

Coexisting BRAF-Mutated Langerhans Cell Histiocytosis and Primary Myelofibrosis with Shared JAK2 Mutation

Langerhans cell histiocytosis (LCH) is an infrequent disease, characterized by oligoclonal proliferation of immature myeloid-derived cells. However, the exact pathogenesis remains unknown. In rare cases, LCH is present in patients with concomitant myeloid proliferative neoplasms. Here, we describe a 69-year-old male, who presented with a maculopapular rash covering truncus, face, and scalp. A cutaneous ulcerating lesion on the right cheek led to a biopsy showing LCH. Lesional cells were BRAF ^V600E and JAK2 ^V617F mutated. A bone marrow aspirate showed no infiltration of Langerhans cells, but alterations consistent with primary myelofibrosis (PMF) and a polymerase chain reaction test were positive for JAK2 ^V617F. Our case highlights an uncommon condition of two hematological malignancies present in the same patient. The identification of the BRAF ^V600E mutation supports previous findings of this mutation in LCH. Interestingly, a JAK2 ^V617F mutation was found in both LCH and PMF cells, indicating a possible clonal relationship between the two malignancies.

Mixed Langerhans Cell Histiocytosis and Erdheim-Chester Disease in a Girl: A Rare and Puzzling Diagnosis

OBJECTIVE

The objective of this study was to report the case of a girl diagnosed as suffering from multisystem, BRAF V600E-positive refractory Langerhans cell histiocytosis (LCH) and coexistent Erdheim-Chester disease (ECD) with perirenal, intracranial involvement and the dramatic response to clofarabine treatment.

OBSERVATIONS

Histiocytoses are rare diseases with a broad clinical spectrum. Recent evidence supports a molecular and clinical overlap between LCH and ECD, and mixed LCH/ECD is now a separate entity. However, only a few pediatric cases of mixed disease have been reported in the literature.

CONCLUSIONS

In a child with refractory, multisystem histiocytosis and atypical presentations, mixed LCH/ECD should be suspected in the differential diagnosis.

Histiocytosis and Neoplasms of Macrophage-Dendritic Cell Lineages: Multimodality Imaging with Emphasis on PET/CT

Histiocytosis is a rare inflammatory process characterized by pathologic infiltration and accumulation of cells derived from the monocytic lineage in normal tissue. It encompasses more than 100 different subtypes of disorders that were recently classified into five main groups: (a) Langerhans-related histiocytosis, (b) Rosai-Dorfman histiocytosis, (c) cutaneous and mucocutaneous histiocytosis, (d) malignant histiocytosis, and (e) hemophagocytic lymphohistiocytosis and macrophage activation syndrome. Langerhans cell histiocytosis is the most common histiocytic disorder. Less common types include Erdheim-Chester disease, Rosai-Dorfman disease, adult and juvenile xanthogranuloma, necrobiotic xanthogranuloma, histiocytic sarcoma, interdigitating dendritic cell sarcoma, Langerhans cell sarcoma, and hemophagocytic lymphohistiocytosis. Although the pathogenesis of these disorders may be attributable to mutations in the oncogenic driver, recent discoveries have shown that inflammation and fibrosis secondary to mutated histiocytes, rather than a proliferative cell mechanism, result in manifestation of the disease. Diagnosis, which relies on a multidisciplinary approach, is challenging and often delayed because clinical findings are nonspecific and may mimic malignant processes at radiologic evaluation. Compared with conventional imaging, PET/CT allows detection of the increased metabolic activity in histiocytes. Diagnostic algorithms for histiocytic disorders should include functional imaging with fluorine 18 (¹⁸F) fluorodeoxyglucose (FDG) PET/CT, which provides a comprehensive whole-body evaluation of their potential involvement with multiple organ systems and allows monitoring of therapeutic response. The most recent revised classification, pathophysiologic and clinical manifestations, sites of involvement, and imaging features of histiocytosis are described in this review and a multimodality approach is used, with emphasis on ¹⁸F-FDG PET/CT evaluation. ^©RSNA, 2021.

Congenital Unilesional Cutaneous Langerhans Cell Histiocytosis: A Case Report

ABSTRACT

Langerhans cell histiocytosis (LCH) is a clonal proliferation of bone-marrow-derived cells, which normally reside as epidermal and mucosal dendritic cells involved in antigen presentation. It is a rare disease more common in children than adults, that is believed to be neoplastic in most cases. The diagnosis is based on clinical and radiological findings in combination with histopathologic, immunophenotypic, or ultrastructural analyses. LCH have a broad spectrum of clinical manifestations, ranging from benign cutaneous lesions to malignant multisystem disease. Based on the extent of involvement at diagnosis, LCH can be divided in single-system LCH when only one organ or system is involved, usually with multiple lesions, and multisystem LCH, when 2 or more organs or systems are involved at diagnosis. One variant of LCH is characterized by congenital isolated cutaneous involvement. It typically manifests at birth or in the postnatal period with a widespread eruption of red-to-brown papulo-nodules or, more uncommonly, a solitary lesion. The overall prognosis for single lesion skin limited LCH is excellent and most lesions spontaneously resolve within 4-18 weeks. Systemic involvement is rare. Skin findings cannot predict systemic disease and obtaining an oncology consultation is recommended for further evaluation. Herein, we present an additional case in a full-term, well-appearing, female infant with an isolated, asymptomatic, ulcerated, papule of the left arm, that was noted at birth.

Solitary juvenile xanthogranuloma of the hypopharynx. Clinico-pathologic study in a child with β-Thalassemia Major and Cutaneous Mastocytosis

Juvenile Xanthogranuloma (JXG), the most common pediatric non-Langerhans cell histiocytosis, may rarely occur in association with Neurofibromatosis (types 1 and 2), Juvenile Myelomonocytic Leukemia and Cutaneous Mastocytosis (CM) and, morphologically, mimics Erdheim-Chester Disease tissue lesions and ALK-positive histiocytosis. We describe a 4-year-old girl with Beta-Thalassemia Major who developed an hypopharyngeal BRAFV600E- and ALK-negative JXG and CM. JXG has been rarely reported in the aerodigestive tract and in association with CM. In this molecular era, knowledge of genetic heterogeneity of JXG and clinical scenarios in which it may develop is essential for the appropriate diagnosis and treatment of each individual patient.

Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare but increasingly recognized multi-system disorder. Its diagnosis and treatment require integration of clinical information, imaging studies, and pathology studies. Of note, ECD can now be defined as a clonal myeloid disorder due to mutations which activate mitogen-activated protein kinase (MAPK) pathways and where an inflammatory milieu is important in the pathogenesis and clinical manifestations of the disease. Biopsy demonstrating characteristic histopathologic features in addition to clinical and radiographic features, most often sclerosing long bone involvement, is required to establish a diagnosis. Detection of somatic MAPK pathway mutations can also assist in the differential diagnosis of ECD and related histiocytic neoplasms. Also, genetic analysis establishing BRAF and RAS mutational status is critical in all ECD patients, as these features will impact therapy with MAPK inhibition. Therapy is recommended at diagnosis in all patients, except for those patients with minimally symptomatic disease. Prospective therapeutic trials are essential to furthering therapeutic progress in ECD.

Erdheim-Chester disease: An in vivo human model of Mϕ activation at the crossroad between chronic inflammation and cancer

Erdheim-Chester disease (ECD) is a rare histiocytosis characterized by infiltration of multiple tissues by CD68⁺ foamy Mϕs (or 'histiocytes'). Clinical manifestations arise from mass-forming lesions or from tissue and systemic inflammation. ECD histiocytes harbor oncogenic mutations along the MAPK-kinase signaling pathway (BRAF^V600E in more than half of the patients), and secrete abundant pro-inflammatory cytokines and chemokines. Based on these features, ECD is considered an inflammatory myeloid neoplasm, and is accordingly managed with targeted kinase inhibitors or immunosuppressive and cytokine-blocking agents. Evidence is emerging that maladaptive metabolic changes, particularly up-regulated glycolysis, represent an additional, mutation-driven feature of ECD histiocytes, which sustains deregulated and protracted pro-inflammatory activation and cytokine production. Besides translational relevance to the management of ECD patients and to the development of new therapeutic approaches, recognition of ECD as a natural human model of chronic, maladaptive Mϕ activation instructs the understanding of Mϕ dysfunction in other chronic inflammatory conditions.

Erdheim-Chester disease with asymmetric talus involvement: A case report

BACKGROUND

Erdheim-Chester disease (ECD) is a rare multi-system or multi-organ histiocytic proliferative disease with diverse clinical manifestations, and the development of the disease is complex, which makes clinical diagnosis and treatment difficult. The characteristic clinical manifestations include multi-organ involvement, especially in the symmetrical diaphysis and metaphysis of the bilateral extremities. ECD with a unilateral talus lesion is extremely rare. Here, we report an unusual case of ECD invading the asymmetric talus and tibia without involving other organs. The patient had good outcome after surgery.

CASE SUMMARY

We report a case of a 67-year-old man who was referred to our outpatient department because of left ankle chronic pain for 5 years, which exacerbated after a foot sprain 6 mo previously. We discovered multiple sclerotic lesions of the tibia and talus on his previous X-ray films, which were initially missed in a local hospital. Therefore, enhanced computer computed tomography (CT) and magnetic resonance imaging were performed. These examinations showed multiple lesions in the bone marrow cavity of the left tibia, and cortical sclerosis and osteonecrosis of the left talus. Specimens were collected via bone puncture from the two lesions, and a final diagnosis of ECD was confirmed by pathological and immunohistochemical examinations. In addition, other auxiliary examinations including head CT, pulmonary CT, spinal CT, abdominal CT, cardiac ultrasound and thyroid ultrasound showed no obvious abnormalities. The patient underwent surgery for the tibia lesion scraping and talus lesion scraping combined with cement casting. The patient started on a progressive rehabilitation at 4 wk, and felt no pain after surgery. During a 2-year follow-up period, the patient exercised normally without pain, and there were no signs of recurrence.

CONCLUSION

This study shows that surgery treatment may also achieve good results for ECD patients with only bone involvement.

Mammary Extranodal Rosai-Dorfman Disease With and Without Associated Axillary Lymphadenopathy: Insights for Practitioners of Breast Pathology

Rosai-Dorfman disease is a rare proliferative histiocytic disorder of lymph nodes that is descriptively known as sinus histiocytosis with massive lymphadenopathy. Extranodal involvement of the parenchyma of the breast is uncommonly reported, with fewer than 50 cases of mammary extranodal disease detailed in the English-language literature. We characterize a retrospective series of adult female patients from a single institution with Rosai-Dorfman disease of the breast and axillary lymph nodes. Because Rosai-Dorfman disease of the breast and axillary lymph nodes may clinically, radiographically, and histologically mimic breast carcinoma and other conditions, we present an illustrated review of the disease and its relevant differential diagnoses in hopes of raising awareness and allowing for accurate management of affected patients.