A rare case of facial cutaneous Rosai-Dorfman disease clinically mimicking basal cell carcinoma followed by multiple myeloma after 2 years

Rosai-Dorfman disease (RDD) is a rare non-Langerhans cell histiocytosis disorder characterized by the proliferation of histiocytes within the lymph nodes. Extranodal involvement can occur; however, only 10% of extranodal RDD involve the skin. We present a unique case of a 66-year-old woman with cutaneous RDD followed by the development of multiple myeloma (MM). To our knowledge, this is only the second reported case where RDD preceded a diagnosis of MM, with the first documented instance occurring in 2018. The patient presented to the dermatology clinic with a 5-year history of painless, solitary lesion over the right cheek. Local examination revealed a single 6 mm x 7 mm well-circumscribed pearly telangiectatic lesion resembling basal cell carcinoma over the right nasolabial fold and cheek. The lesion was excised with a 3 mm circumferential margin. Histopathology showed a mixed lymphohistiocytic cell infiltrate with emperipolesis and immunohistochemical staining patterns consistent with RDD. Two years later, the patient presented with hip pain and was diagnosed with MM. She was treated with lenalidomide, bortezomib, and dexamethasone, and was later maintained on lenalidomide. Our case adds to the limited evidence suggesting a potential association between RDD and MM. Further research in this field is required to promptly identify and manage patients with such a presentation in the future.

Treatment of cutaneous Rosai-Dorfman disease with ALA-PDT combined with low-dose oral corticosteroids: A case report

Cutaneous Rosai-Dorfman Disease (CRDD), a rare form of Rosai-Dorfman Disease (RDD), lacks established treatment guidelines. In this case report, we detailed a successful case of CRDD management in a 50-year-old woman with facial lesions. Our treatment included 5-aminolevulinic acid photodynamic therapy (ALA-PDT) and low-dose oral corticosteroids. Remarkable improvement was evident after six ALA-PDT courses, and a one-year follow-up confirmed sustained remission. This case highlights the potential of combining ALA-PDT with low-dose corticosteroids as a promising therapeutic strategy for CRDD. Further research is necessary to fully elucidate its mechanisms and effectiveness.

Rosai-Dorfman disease of the cauda equina: illustrative case

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare, nonmalignant histiocytosis. It typically occurs in lymph nodes, skin, and soft tissues, but numerous reports of central nervous system involvement exist in the literature. The peripheral nervous system has rarely been involved. In this study, the authors present a case of RDD isolated to the cauda equina. The presentation, management, surgical technique, and adjunctive treatment strategy are described.

OBSERVATIONS

A 31-year-old female presented with 6 months of progressive left lower-extremity numbness involving the lateral aspect of the foot and weakness of the left toes. Magnetic resonance imaging of the lumbar spine demonstrated a homogeneously enhancing intradural lesion involving the cauda equina at the L2-3 levels. Histopathology after resection revealed a histiocytic infiltrate, positive for CD68 and S100, and emperipolesis consistent with RDD. No adjuvant therapy was administered, and the patient had full remission at the 1-year follow-up. Only five other cases of intradural RDD lesions of the cauda equina have been reported in the literature.

LESSONS

RDD of the cauda equina is an especially rare and challenging diagnosis that can mimic other dura-based lesions, such as meningiomas. A definitive diagnosis of RDD relies on pathognomonic histopathological and immunohistochemical findings.

Synchronous occurrence of primary cutaneous B-cell lymphoma and cutaneous Rosai-Dorfman disease in distinct lesions: A unique association

Rosai-Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy (SHML), is a rare subtype of reactive histiocytosis which is seldom associated with Hodgkin's and non-Hodgkin's lymphomas. To date, the coexistence in the same patient of extra nodal SHML and primary cutaneous B-cell lymphoma (PCBCL) has been reported in the literature, as metachronous diagnosis in the anatomical area of the original PCBCL or synchronous occurrence in the same lesions. However, no data have been published as for synchronous occurrence of the two pathological entities in distinct anatomical sites. Herein, we report the first ever described synchronous occurrence of PCBCL and SHML, detected in distinct lesions, affecting the same patient. The complete resolution of the patient's PCBCL after rituximab treatment and the concomitant regression of SHML suggest that this clinically benign reactive histiocytic proliferation, potentially triggered by the lymphoma microenvironment itself, may take place not only in the site of the PCBCL lesion, but also in other distant areas not directly affected by the primary cutaneous lymphoma.

Histiocytic neoplasms: a brief review and differential diagnosis

Histiocytic neoplasms (HNs) include juvenile xanthogranuloma, Erdheim-Chester disease, Rosai-Dorfman disease, ALK-positive histiocytosis, and histiocytic sarcoma in the 5th edition of the World Health Organization Classification of Haematolymphoid Tumours. These entities are clinicopathologically distinctive, and typical histological findings have been established. However, the common feature of a proliferation of histiocytic cells often leads to morphological overlap among HNs, and also necessitates a differential diagnosis from several non-HNs or non-neoplastic conditions. In this review, we provide a brief summary of the clinical findings, molecular features, histopathologies, and immunophenotypes of HNs, as well as to discuss their differential diagnosis.

Cerebral manifestation and diagnostic dilemma of Rosai-Dorfman disease

Rosai-Dorfman disease (RDD) is a rare, S100-positive histiocytic proliferation, that can cause both nodal and extranodal illness. We present a case of a 53-year-old male patient. Magnetic resonance imaging described a plaque-like meningeal lesion, and the preoperative diagnosis was meningioma. Histologically, dense infiltration of lymphocytes, plasma cells, and histiocytes was seen, furthermore, the presence of emperipolesis in the sample was pronounced. In the histiocytes nuclear and cytoplasmic positivity with S100 protein, and nuclear positivity with Cyclin D1 was observed. The case was concluded as RDD. Morphological appearance of intracranial RDD with imaging procedures can present a differential diagnostic challenge. The correct diagnosis is based on the presence of histiocytes with emperipolesis, and properly defined immunohistochemical characteristics.

Comparison of neuroimaging features of histiocytic neoplasms with central nervous system involvement: a retrospective study of 121 adult patients

OBJECTIVES

To compare neuroimaging characteristics of three types of histiocytoses, namely Langerhans cell histiocytosis (LCH), Erdheim-Chester disease (ECD), and Rosai-Dorfman disease (RDD), with central nervous system (CNS) involvement.

METHODS

A total of 121 adult patients with histiocytoses (77 LCH, 37 ECD, and 7 RDD) and CNS involvement were retrospectively included. Histiocytoses were diagnosed based on histopathological findings combined with suggestive clinical and imaging features. Brain and dedicated pituitary MRIs were systematically analyzed for tumorous, vascular, degenerative lesions, sinus, and orbital involvement and for hypothalamic pituitary axis involvement.

RESULTS

Endocrine disorders, including diabetes insipidus and central hypogonadism, were more common in LCH patients than in ECD and RDD patients (p < 0.001). In LCH, tumorous lesions were mostly solitary (85.7%), located in the hypothalamic pituitary region (92.9%), and without peritumoral edema (92.9%), while in ECD and RDD, tumorous lesions were often multiple (ECD: 81.3%, RDD: 85.7%), their distribution was more widespread with meninges mostly involved (ECD: 75%, RDD: 71.4%), and they most likely presented with peritumoral edema (ECD: 50%, RDD: 57.1%; all p ≤ 0.020). Vascular involvement was an exclusive imaging characteristic of ECD (17.2%), which was not observed in LCH or RDD; this was also associated with a higher risk of death (p = 0.013, hazard ratio = 11.09).

CONCLUSION

The typical characteristic of adult CNS-LCH was endocrine disorders with radiological findings limited to the hypothalamic pituitary axis. The pattern of multiple tumorous lesions with predominant involvement of meninges was the main manifestation of CNS-ECD and CNS-RDD, while vascular involvement was pathognomonic for ECD and associated with poor prognosis.

CLINICAL RELEVANCE STATEMENT

Involvement of the hypothalamic-pituitary axis is the typical imaging characteristic of Langerhans cell histiocytosis. Multiple tumorous lesions, predominantly involving but not limited to meninges, occur in most Erdheim-Chester disease and Rosai-Dorfman disease patients. Vascular involvement occurs only in Erdheim-Chester disease patients.

KEY POINTS

• The different distribution patterns of brain tumorous lesions can help differentiate among LCH, ECD, and RDD. • Vascular involvement was an exclusive imaging finding of ECD and was associated with high mortality. • Some cases with atypical imaging manifestations were reported to further expand the knowledge on these diseases.

Facial Cutaneous Rosai-Dorfman Disease: Dermoscopic Findings with Successful Surgical Treatment

Rosai-Dorfman disease (RDD) is a rare non-Langerhans cell histiocytosis characterized by an accumulation of activated histiocytes within the affected tissues. It is a heterogeneous disease that includes the classical (nodal) and extra-nodal variants. The cutaneous form of the disease without the characteristic lymphadenopathy is rare and is often misdiagnosed as other dermatologic diseases. Misdiagnosis as lymphoproliferative and infectious diseases such as lymphoma and tuberculosis have been reported in the literature. Herein, we report a case of facial cutaneous RDD with successful surgical treatment. In addition, we provide dermoscopic findings and literature review as dermoscopy can be a useful adjuvant tool in the diagnosis of cutaneous RDD.

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

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

Rosai-Dorfman disease of the breast: a clinicoradiologic and pathologic study

Rosai-Dorfman disease (RDD) is an uncommon histiocytic disorder typically involving lymph nodes and less frequently extranodal tissues. RDD involving the breast is rare and may clinically and radiologically mimic neoplastic and non-neoplastic disorders. We report seven patients with breast RDD, describe their clinicoradiologic and pathologic features, and discuss the differential diagnosis. Patients, ranging from 15 to 74 years of age, presented with unilateral and unifocal (5/7) or bilateral and multifocal (2/7) masses. RDD was either confined to the breast (6/7) or concurrently involved a lymph node (1/7). Masses ranged from 8 to 31 mm, categorized as Breast Imaging-Reporting and Data System (BI-RADS) 4 (6/7) or 5 (1/7). All cases showed similar morphology with many large histiocytes displaying emperipolesis with associated fibrosis and dense lymphoplasmacytic infiltrate. The abnormal histiocytes co-expressed CD68/CD163, S100, OCT2, and Cyclin D1 (7/7), and were negative for CK AE1/AE3 (7/7), CD1a (7/7), and BRAF V600E (6/6). Flow cytometry (n = 3), kappa/lambda in situ hybridization (n = 5), and IgG4/IgG immunohistochemistry (n = 1) did not reveal lymphoma or IgG4-related disease. No mycobacterial or fungal organisms were identified on acid-fast bacillus (AFB) and Grocott methenamine silver (GMS) stains (n = 5). Three patients underwent complete excision and none recurred or progressed to systemic disease during follow-up (88-151 months). In summary, breast RDD should be included in the differential diagnosis of a mass-forming breast lesion. Histopathology with ancillary studies and clinicoradiologic correlation is essential for accurate diagnosis and optimal clinical management. Patients with RDD of the breast have an excellent prognosis after complete excision.

Primary Bilateral Intraosseous Rosai-Dorfman Disease

Rosai-Dorfman disease (RDD) is a rare histiocytic proliferative disease of unknown etiology. Typically presenting with cervical adenopathy and constitutional symptoms, RDD involves bone in less than 10% of cases-and rarely presents as a primary intraosseous lesion. In this report, we describe the presentation of primary, bilateral intraosseous RDD, the first known case in the literature. Asymmetrically involving the lateral femoral condyles of a 59-year-old male, the lesion was discovered incidentally during evaluation and workup for giant cell tumor of bone involving the left tibia. Confirmation of the diagnosis required multiple biopsies and extensive evaluation-reflecting the diagnostic challenge associated with this case. We discuss the clinical, radiological, and pathological findings that allowed us to establish the diagnosis-as well as key differential diagnostic considerations and clinical outcome to date.

Malignus emlőtumor? Gyulladásos emlőelváltozás? Ritka benignus kórkép?

Case-report

Rosai-Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy is a rare, benign non-Langerhans cell histiocytosis, that typically involves the lymph nodes, but may also involve extranodal sites. We present a 58- years- old female patient who complained of a palpable mass in her left breast surrounded by 15-20 livid cutaneous lesions, resembling malignant breast cancer with cutaneous metastasis. Despite of core biopsy of the tumor and excisional biopsy one of the lesions, correct diagnosis of RDD was achieved only by complete pathological examination of the whole lesion after surgical excision.

Conclusion

Rosai-Dorfman disease confined to the breast is extremely rare, that clinically may mimic breast cancer.

Intracranial Rosai‑Dorfman disease complicated by mucosa‑associated lymphoid tissue: A case report

Intracranial Rosai-Dorfman disease (RDD) is a rare, self-limiting histiocytic disease of unknown etiology. Extranodal marginal zone lymphoma of the mucosa-associated lymphoid tissue (MALT lymphoma) is also rare and intracranial RDD complicated by MALT lymphoma is even rarer. The present study reports a case of a 55-year-old female who was admitted to The Second Affiliated Hospital of Jiaxing University (Jiaxing, China) with headache for half a month and ptosis of the right eyelid for 4 days. Computerised tomography and magnetic resonance imaging revealed a right parasellar tumor and, subsequently, subtotal resection of the tumor was performed. Postoperative pathology revealed intracranial RDD complicated by MALT lymphoma. The patient received chemotherapy after surgery and achieved good therapeutic effects. After 12 months of follow-up, the residual tumor disappeared and the ptosis prominently improved. To the to the best of the authors' knowledge, the present case is the first reported case of an adult intracranial RDD complicated by MALT lymphoma.

Rosai-Dorfman-Destombes Disease in the Pediatric Head and Neck

BACKGROUND

Rosai-Dorfman-Destombes disease (RDD), or sinus histiocytosis with massive lymphadenopathy, is a rare form of non-Langerhans cells histiocytosis. It has a wide-ranging variability in presentation since first described in 1969 but much of its characteristics in children remain unknown.

METHODS

A retrospective chart review of children diagnosed with RDD at a tertiary care children's hospital was conducted from 2000 to 2021.

RESULTS

Twelve RDD patients were identified, with an average age of 7 years (SD 4.3). Males comprised 58% of the cohort, and African American ethnicity was most common (42%). Nodal RDD was found in 7 patients (58%). Nine patients (75%) presented RDD within the head and neck, 6 of whom had nodal RDD. The most common presentation was cervical lymphadenopathy, which most often involved levels V (67%), II (56%), III (44%), and I (11%), in order of frequency. Recurrence and persistence of disease after initial treatment was common, with 5 (42%) being disease free at the time of the last follow up. Fifty-eight percent (7/12) developed recurrence or had persistent disease and 4 required adjuvant systemic treatment with corticosteroids and/or chemotherapy. One patient succumbed after developing treatment related acute myelodysplastic leukemia (t-AML) from chemotherapy used to treat recurrent RDD.

CONCLUSION

Pediatric RDD presents at a young age and most commonly involving cervical lymphadenopathy. Ongoing surveillance in the setting of persistence or recurrence without clearly defined prognostic risk factors is important.

Characterizing Rosai-Dorfman disease with [18F]FDG PET/CT: a retrospective analysis of a single-center study

OBJECTIVES

Rosai-Dorfman disease (RDD) is a rare non-Langerhans cell histiocytic proliferative disorder. We performed a retrospective study to characterize the clinical and [18F]FDG PET/CT features of RDD.

METHODS

We retrospectively recruited 38 RDD patients with [18F]FDG PET/CT scan in our center. [18F]FDG PET/CT features were assessed, and clinical and follow-up data were recorded.

RESULTS

In the recruited patients, 20/38 (52.6%) patients had single-system disease, while others (18/38, 47.4%) had disease affecting multiple system. RDD most commonly involved the upper respiratory tract (47.4%), followed by cutaneous/subcutaneous lesion (39.5%), lymph node (36.8%), bone (31.6%), central nervous system (28.9%), and cardiovascular system (13.2%) in the recruited patients. In PET/CT, the RDD lesions were FDG-avid, and the SUVmax of the hottest lesion in an individual patient was positively correlated with C-reactive protein levels (r = 0.418, p = 0.014), and negatively correlated with hemoglobin levels (r =  -0.359, p = 0.036). The overall response rate of the first-line treatment was 80.8% in newly diagnosed RDD patients, and for patients with relapsed/progressive RDD, the overall response rate was 72.7%.

CONCLUSION

[18F]FDG PET/CT could be a useful tool for evaluating RDD.

KEY POINTS

• About half of the patients with Rosai-Dorfman disease had single-system disease, while others had disease affecting multiple system. Rosai-Dorfman disease most commonly involved the upper respiratory tract, followed by cutaneous/subcutaneous lesion, lymph node, bone, central nervous system, and cardiovascular system. • In [18F]FDG PET/CT, Rosai-Dorfman disease was usually hypermetabolic, and the SUVmax of the hottest lesion in an individual patient was positively correlated with C-reactive protein levels. • Rosai-Dorfman disease usually has a high overall response rate after treatment.

Rosai-Dorfman disease mimicking craniopharyngioma: a challenging differential diagnosis. Illustrative case

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare non-Langerhans histiocytic disorder with less than 5% central nervous system involvement and is often mistaken for meningioma given the similarity in imaging features. The authors present the unique case of a 44-year-old female who presented with ongoing visual impairment.

OBSERVATIONS

A purely suprasellar mass was noted on magnetic resonance imaging and was initially diagnosed as craniopharyngioma. Unexpectedly, the pathology report revealed RDD.

LESSONS

To date, only six cases of sellar RDD have been reported, and our case is the first reported with a purely suprasellar presentation. No standard treatment has been established for RDD, and next-generation sequencing may be a promising therapeutic option.

Neurological Manifestations of Histiocytic Disorders

PURPOSE OF REVIEW

Histiocytic disorders, including Erdheim-Chester disease (ECD), Langerhans cell histiocytosis (LCH), and Rosai-Dorfman disease (RDD), are rare neoplasms that may present with a spectrum of neurologic involvement. Diagnostic delay is common due to heterogeneity in presentation and challenging pathology.

RECENT FINDINGS

Recent advances in the treatment of these diseases targeted towards mutations in the MAP kinase pathway have led to an improved prognosis in these patients with neurologic involvement. It is critical for clinicians to have a high index of suspicion to allow for early targeted treatment and optimize neurologic outcomes. A systematic approach to diagnosis is presented in this article to allow for accurate diagnosis of these rare diseases.

Rosai-Dorfman Disease of the Rectum: Newly Identified Genetic Point Mutations and Robotic Resection

Rosai-Dorfman disease (RDD) is a rare disease characterized by histiocytic proliferation which typically presents as massive, painless, cervical lymphadenopathy in children or young adults. GI involvement is exceedingly rare with only 20 documented cases to date. Of those 20 cases, only 3 cases have involved the rectum. Here, we present 2 cases of rectal RDD with attention paid to the diagnostic and technical challenges presented by this disease. When presenting as a perirectal mass, RDD can be mistaken for other lesions to include malignancy, leading to surgical removal. We present a video of a robotic low-anterior resection with intracorporeal anastomosis in order to remove a pelvic mass involving the rectum, initially considered to be a stromal tumor. In addition, we describe a copy number variation in AKT and 3 point mutations detected by next generation sequencing, which had not been previously reported in association with this disease.

Testicular Rosai-Dorfman disease clonally related to CMML - Case report and literature review

BACKGROUND

Rosai-Dorfman disease (RDD), a rare form of non-Langerhans cell histiocytosis with heterogenous clinical features, arises from precursor cells that give rise to cells of the histiocytic and monocytic lineages. An association with hematological neoplasms has been reported. Testicular RDD is rarely described, with only 9 reported cases in the literature. Genetic data to assess clonal relationships between RDD and other hematological neoplasms remain scarce. We describe an instance of testicular RDD against a background of chronic myelomonocytic leukemia (CMML), with genetic studies in both neoplasms.

CASE PRESENTATION

A 72-year-old patient with a history of CMML sought evaluation of growing bilateral testicular nodules. Solitary testicular lymphoma was suspected; orchidectomy was performed. The diagnosis of testicular RDD was established morphologically and confirmed immunohistochemically. Molecular analysis of testicular lesions and of archived patient bone marrow revealed the KRAS variant c 0.35 G>A / p.G12D in both, suggesting a clonal relationship.

CONCLUSION

These observations support classifying RDD as a neoplasm that can be clonally related to myeloid neoplasms.

How I Diagnose Rosai-Dorfman Disease

OBJECTIVES

Rosai-Dorfman disease (RDD) is one of 3 major types of histiocytosis, along with Erdheim-Chester disease and Langerhans cell histiocytosis. While historically, RDD was considered a benign self-limited condition, current data show MAPK/ERK pathway mutations in 30% to 50% of cases, indicative of a clonal process. Rosai-Dorfman disease was incorporated as a histiocytic neoplasm in the fifth edition of the World Health Organization classification of hematopoietic tumors and the International Consensus Classification.

METHODS

We discuss the diagnosis of RDD using 2 illustrative cases, interpretative challenges, and a diagnostic algorithm.

RESULTS

Rosai-Dorfman disease involves nodal and extranodal sites, including skin, sinuses, salivary gland, orbit, central nervous system, kidney, and bone. In a subset, RDD can coexist with other neoplasms (lymphomas, other histiocytosis) or autoimmune disease. Morphologically, RDD histiocytes are characterized by enlarged round to oval nuclei, distinct nucleoli, and voluminous cytoplasm with engulfment of inflammatory cells (emperipolesis). By immunohistochemistry, they express CD68, CD163 (majority), S100, OCT2, and cyclin D1. Appropriate use of ancillary studies is important to support the diagnosis of RDD while excluding other histiocytic neoplasms and reactive histiocytic proliferations.

CONCLUSIONS

Management of RDD is dependent on the extent of organ involvement and clinical symptoms. In patients who require therapy, next-generation sequencing is recommended to identify MAPK/ERK pathway mutations for targeted therapy.

Rosai-Dorfman Disease in the Skull Base: A Case Series Study

OBJECTIVE

Rosai-Dorfman disease (RDD) is a rare, idiopathic, and non-neoplastic histio-proliferative disease that is uncommon in the central nervous system. Hence, reports of management of RDD in the skull base are scarce and only a few studies on skull base RDD are available. The objective of this study was to analyze the diagnosis, treatment, and prognosis of RDD in the skull base and explore an appropriate treatment strategy thereof.

METHODS

Nine patients with clinical characteristics and follow-up data from our department between 2017 and 2022 were included in this study. From this information, the clinical profiles, imaging, treatment, and prognosis data were collected.

RESULTS

There were 6 male and 3 female patients with skull base RDD. These patients ranged in age from 13 to 61 years, with a median age of 41 years. The locations included 1 anterior skull base orbital apex, 1 parasellar region, 2 sellar regions, 1 petroclivus, and 4 foramen magnum regions. Six patients underwent total resection and 3 underwent subtotal resection. Patient follow-up lasted 11-65 months, with a median duration of 24 months. One patient died, 2 experienced recurrence, and the other patients' lesions were stable. The symptoms worsened and new complications occurred in 5 patients.

CONCLUSIONS

Skull base RDDs are intractable diseases with a high rate of complications. Some patients are at risk of recurrence and death. Surgery may be the basic treatment for this disease, and combined therapy including targeted therapy or radiation therapy may also be a valuable therapeutic strategy.

Primary diffuse Rosai-Dorfman disease in central airway: a case report and literature review

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare benign non-langerhans cell histiocytosis, mainly involving lymph nodes and skin. It is even rarer occurring only in central airway of lung and in diffuse form. Central airway RDD is similar to malignant tumor in imaging by radiological method and in bronchoscopy features. It is difficult to differentiate it from primary airway malignant tumor and to diagnose correctively in time.

CASE PRESENTATION

Here we present a rare case of 18-year-old male diagnosed with primary diffuse RDD in central airway. Although the features examined by enhanced chest computed tomography, positron emission tomography/computed tomography, diffusion-weighted imaging of enhanced chest MRI and bronchoscopy indicate to be malignant tumor, the patient was definitely confirmed by multiple transbronchial biopsies and immunohistochemistry. After two transbronchial resections, the patient's symptoms of paroxysmal cough, whistle sound and shortness of breath were significantly reduced, as well as the airway stenosis was significantly improved. After 5 months of follow-up, the patient had no symptoms and the central airway were unobstructed.

CONCLUSIONS

Primary diffuse RDD in central airway is characterized by intratracheal neoplasm, which is usually suspected as malignant tumor according to radiological image and bronchoscopy. Pathology and immunohistochemistry are necessary for definite diagnosis. Transbronchial resection is effective and safe for patients with primary diffuse RDD in central airway.

Recurrent central nervous system Rosai-Dorfman disease with KRAS mutation: a case report

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare, non-Langerhans cell histiocytosis of unknown etiology. we report a very rare case of recurrent central nervous system RDD with KRAS gene mutation and review the literature to improve our understanding of this disease.

CASE PRESENTATION

A 19-year-old male patient was admitted to our hospital for headache. Cranial magnetic resonance imaging revealed a mass of abnormal signal shadows in the prepontine cistern. The mass was surgically removed and the patient was consequently diagnosed with intracranial Rosai-Dorfman disease. Seven months later, pathological examination confirmed that the RDD had recurred. Next-generation sequencing found KRAS mutation in exon 4 (C.351A > C. P. K117n).

CONCLUSION

RDD of the CNS has no distinct clinical manifestations and imaging characteristics, and the final diagnosis should be based on the results of the pathological examination. Although RDD is not currently classified as a neoplastic disorder, some evidence of clonality has changed our understanding of it. Follow up examinations over a long period are necessary to determine the efficacy of treatment.

OCT2 expression in histiocytoses

Diagnosis of histiocytosis can be difficult and one of the biggest challenges is to distinguish between reactive and neoplastic histiocytes on histology alone. Recently, OCT2 nuclear expression was reported in Rosai-Dorfman disease (RDD). Our purpose was to expand the testing of OCT2 on a broader variety of sporadic or H syndrome-related histiocytoses. Cases of histiocytoses were retrieved from the files of Ambroise Paré Pathology Department. All slides and molecular analyses were reviewed, and staining was completed with immunohistochemistry for OCT2. A total of 156 samples from different localizations were tested. Among sporadic cases, 52 patients had RDD, and 10 patients had mixed histiocytosis combining RDD with Erdheim Chester disease (ECD, n = 8), Langerhans cell histiocytosis (LCH, n = 2) or juvenile xanthogranuloma (JXG, n = 1). All these patients were positive for OCT2 in RDD characteristic histiocytes. Twenty-three patients had ECD and all but two (91% - 21/23) were negative for OCT2. By contrast, OCT2 was positive in 11/27 (41%) LCH and 6/16 (38%) JXG. Among the 10 samples of H syndrome-associated histiocytosis, 3 had typical RDD histology, 6 had unclassified histiocytosis, and one had mixed RDD-LCH; all were positive for OCT2. On 16 samples of granulomatous lymphadenitis, OCT2 was negative in epithelioid histiocytes. Our study shows that OCT2 has a sensitivity of 100% for RDD cases and mixed histiocytoses with an RDD component. It is negative in 92% of ECD but expressed in at least 38% of LCH, JXG, and C group histiocytoses. Finally, OCT2 is positive in all H syndrome-related histiocytoses, independent of their histology.

A Rare Case of Rosai-Dorfman Disease Affecting the Brachial Plexus: A Case Report

Sinus histiocytosis with massive lymphadenopathy or Rosai-Dorfman disease is a rare but well-established entity, commonly affecting the lymph nodes of the head and neck. Extranodal presentation, affecting the central nervous system, eye orbit, kidneys, testis, bones, upper respiratory tract, lungs, thyroid, small intestine, and peritoneum, has been reported. We present a case of a rare presentation of Rosai-Dorfman disease affecting the brachial plexus.