Rosai-Dorfman disease: a report of eight cases in a tertiary care center and a review of the literature

Rosaï-Dorfman-Destombes Disease: A Clinical Case Report

Rosaï-Dorfman disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy (SHML), is a rare and benign histoproliferative disorder of unknown etiology. It commonly presents with bilateral, painless cervical lymphadenopathy accompanied by systemic features such as fever and leukocytosis. RDD manifests in two primary forms: a systemic form involving multiple organ systems and a cutaneous form confined to the skin. Histopathological examination typically reveals pericapsular fibrosis, sinusoidal dilation, and the presence of large histiocytes exhibiting emperipolesis (phagocytosed lymphocytes within histiocytes). Extranodal involvement is observed in approximately 43% of the cases, with a predilection for the head and neck regions. Although the precise etiology remains unclear, associations with viral infections such as Epstein-Barr virus (EBV) and human herpesvirus-6 (HHV-6) have been proposed. Management strategies are case-dependent, ranging from observation in cases of spontaneous remission (reported in 20-50% of patients) to more aggressive therapeutic interventions. Here, we describe a pediatric case of RDD managed in Morocco.

Rosai-Dorfman Disease Presenting With FDG-Avid Breast Masses and Axillary Lymph Nodes on PET-CT in a Patient With Recent Diagnosis of Endometrial Carcinoma: A Diagnostic Dilemma

Rosai-Dorfman disease (RDD) is a self-limited, idiopathic, non-neoplastic disorder characterized by the proliferation of phagocytic histiocytes, which can mimic malignant lymphoproliferative disease. Cases of RDD most commonly present as bilateral painless cervical lymphadenopathy, with lesser involvement of the axilla, inguinal, and mediastinal lymph nodes. We present the case of a 62-year-old woman with a history of endometrial serous carcinoma who underwent evaluation at a dedicated breast imaging department after positron emission tomography/computed tomography (PET/CT) revealed breast masses and axillary nodes with increased uptake of fluorodeoxyglucose (FDG). Upon clinical examination, she had bilateral palpable lumps in both breasts and axillae. Subsequent dedicated breast imaging with bilateral diagnostic mammography with tomosynthesis and bilateral complete breast ultrasound were suspicious for malignancy detecting bilateral breast masses and axillary lymphadenopathy corresponding to the FDG-avid findings on PET/CT. Ultrasound-guided core needle biopsies, however, revealed a diagnosis of RDD. This case highlights the unique characteristics of RDD with an atypical clinical presentation suspicious for breast cancer both clinically and radiologically.

Thymic Rosai-Dorfmann disease: a case report

BACKGROUND

Rosai-Dorfman disease (RDD), known as sinus histiocytosis with massive lymphadenopathy, commonly involves lymph nodes in the neck or mediastinum, although extranodal involvement is observed in approximately 40% of RDD patients. RDD involving only the thymus has rarely been reported. Here, we report a case of RDD originating in the thymus. The lesion was surgically removed, and a cure was finally achieved. There was no recurrence after telephone follow-up for 3 years.

CASE PRESENTATION

A 52-year-old male was accidentally found to have a 7 × 6 cm anterior mediastinum lump by chest computed tomography (CT). The mediastinal lesion was resected by surgery, and postoperative pathology revealed RDD originating from the thymus. Regular telephone follow-up after surgery lasted 3 years and showed that the patient remained in good condition without any relevant symptoms.

CONCLUSIONS

RDD originating in the thymus cannot be characterized from CT images and is easily misdiagnosed as a traditional mediastinal tumor. This is mainly because there is so little disease in this area that physicians are not aware of it. We report this case with the hope that clinicians will have a better understanding of this disease. According to our follow-up results, surgery is an effective means of treatment.

Extranodal Rosai-Dorfman disease manifesting as Sjögren's syndrome combined with panuveitis and hypertrophic pachymeningitis: a case report and review of literature

Rosai-Dorfman disease (RDD) is a rare non-Langerhans cell histiocytosis characterized by massive lymphadenopathy and systemic extranodal lesions. We present the case of a 28-year-old woman who presented with recurrent blurred vision in her right eye for 3 months. She developed blindness and atrophy in her left eye a decade prior to presentation. She subsequently developed headache, fever, and impaired mental status. Cranial magnetic resonance imaging indicated hypertrophic pachymeningitis (HP), and 18F-fluoro-2-deoxy-2-d-glucose (FDG) positron emission tomography/computed tomography revealed significant FDG uptake in the left dura mater. Autoimmune testing revealed elevated anti-nuclear, anti-SS-A, and anti-SS-B antibody levels. Incisional biopsy of the atrophic eyeball revealed RDD with marked polyclonal plasmacytosis. The patient was diagnosed with RDD accompanied by multisystem involvement, including Sjögren's syndrome (SS), panuveitis, and HP. Treatment with methylprednisolone for several weeks resulted in significant improvement. This is the first reported case of RDD presenting with SS in combination with panuveitis and HP. Although RDD is rarely diagnosed in young patients, interdisciplinary collaboration is essential to prevent a delayed diagnosis.

Successful anesthesia management with inhalation anesthesia in Rosai-Dorfman disease: a case report

Rosai-Dorfman disease (RDD) is a rare, benign, non-Langerhans cell histiocytic proliferative disease. RDD with central nervous system involvement is extremely rare. Surgical excision is generally regarded as the appropriate treatment of choice for this disease, especially when the lesion causes neurological compression. RDD can be accompanied by systemic symptoms, such as malaise, fever, weight change, leukocytosis, anemia, and hormonal disturbance, which may be challenging during general management. Little is known regarding peri-anesthesia management of this rare disease. We report a case of a patient in his 20s who had recurrent RDD and had general anesthesia with perioperative management. He was obese and hepatic insufficiency. This case report adds to the literature regarding the perioperative anesthetic management of RDD with central nervous system involvement.

Localized retroperitoneal Rosai-Dorfman-Destombes disease as a cause of fever of unknown origin in adults. Case report and review of the literature

•

The localized abdominal RDD could be a possible cause of FUO.

•

RDD should be considered in the differential diagnosis of localized retroperitoneal mass and FUO.

•

FDG-PET/CT is a useful diagnostic tool for initial diagnosis, staging, and follow-up.

•

In localized RDD, the surgery can be a definitive treatment.

A Report of Rosai–Dorfman Disease in an Adolescent

Rosai–Dorfman disease (RDD) is a rare disease of unknown cause. It is a benign self-limiting condition characterized by the accumulation of activated histiocytes in the sinusoids of lymph nodes and/or extranodal tissues. Massive cervical lymphadenopathy as the initial manifestation tends to raise the initial odds in favour of a lymphoma, and thus reducing the threshold to performing a simple biopsy cannot be overestimated. Herein, we report a 13-year-old adolescent who presented with a progressive posterior left-sided neck swelling. Our diagnosis of RDD was established by demonstrating emperipolesis in histology and S100 positivity in immunohistochemistry as stated in the literature. Although the condition is known to be self-limiting, evidence from the literature and our case management shows that medical therapy can hasten remission in pediatric cases.

Coexistent Rosai Dorfman disease and Langerhans cell histiocytosis in an Orbital mass: A Case Report

INTRODUCTION

Rosai Dorfman disease (RDD) is a rare benign histiocytic proliferative disorder of lymph node sinuses. Langerhans cell histiocytosis (LCH) is a solitary or multisystem clonal proliferation of abnormal dendritic cells (Langerhans cells) with varied presentations. The co-occurrence of these two entities is quite rare.

CASE DESCRIPTION

A six-year-old boy presented with multiple mass lesions in the neck since two years and a nodular lesion in right upper eyelid for the past 4 months. He was diagnosed with tubercular lymphadenitis 2 years back, and was given a course of anti-tubercular therapy (ATT) elsewhere. No improvement was seen. Fine needle aspiration cytology (FNAC) of the cervical lymph nodes revealed reactive lymphadenitis while lymph node biopsy showed features of RDD. Excision biopsy of the orbital mass showed features of both RDD and LCH. The patient was started on tablet prednisolone. Six months later, complete resolution of lymph node enlargement and remaining orbital mass was noted. Post operative contrast enhanced Magnetic Resonance Imaging of head and neck was normal.

CONCLUSION

The coexistence of RDD and LCH may be a result of divergent differentiation from a common lineage or a de novo phenotypic evolution.

Rosai-Dorfman disease of thymus with elevated serum anti-acetylcholine receptor antibody: a case report

Rosai-Dorfman disease is a rare disorder of histiocytic proliferation in lymph nodes and at extranodal sites. We herein describe a patient with isolated Rosai-Dorfman disease in the thymus with elevated anti-acetylcholine receptor antibody. We examined the relationship between Rosai-Dorfman disease and elevated anti-acetylcholine receptor antibody. To our knowledge, elevated anti-acetylcholine receptor antibody has not been reported in isolated thymic Rosai-Dorfman disease.

Rosai-Dorfman disease in 6-year-old child: Presentation, diagnosis, and treatment

Rosai-Dorfman disease is referred to as sinus histiocytosis massive lymphadenopathy. We are reporting a rare case of Rosai-Dorfman disease, a case of 6-year-old boy with a history of multiple painless submandibular and cervical lymphadenopathy.

Rosai-Dorfman-Destombes disease: isolated intracranial without nodal involvement presentation. Illustrative case

BACKGROUND

Rosai-Dorfman-Destombes disease is a rare and heterogeneous entity that has been associated with autoimmune, hereditary, and malignant diseases. There is controversy about its etiopathogenesis, clinical course, and therapeutic management.

OBSERVATIONS

The authors report a case of a 61-year-old man with a history of progressive headache without any other symptoms. Magnetic resonance imaging of the brain revealed multiple irregular lesions with an initial diagnostic impression of meningiomatosis. An excisional biopsy was performed, and the pathology report stated the finding was Rosai-Dorfman-Destombes disease.

LESSONS

The uniqueness of this case is its rarity. The isolated intracranial location presents many diagnostic and therapeutic challenges, with radiological and clinical characteristics similar to those of other central nervous system tumors. There is currently no clear evidence of the pathogenesis and therapeutic management of this condition. Follow-up of these patients will help elucidate the natural history of this condition and the benefits of various treatment modalities.

An extremely rare case of Rosai-Dorfman disease in the spleen

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare, multisystemic histiocytic disorder, and commonly manifesting as lymphadenopathy in the young male. Abdominal manifestations of RDD are extremely rare.

CASE PRESENTATION

In August 2018, a 42-year-old man underwent an abdominal ultrasonography examination due to his weight loss of 10 kg in only three months and found a giant solid tumor was found in his spleen. Then, he was admitted to our hospital and diagnosed as a splenic mass via abdominal enhanced CT and MRI. Laparoscopic splenectomy was administrated within six days of admission due to the clear surgical indications. The pathogenesis of RDD remained poorly understood and the disease should be diagnosed based on histopathology and immunohistochemistry (IHC). The mutations in ATM and NFKBIA were observed using next generation sequencing (NGS).

CONCLUSION

We reported a case of splenic involvement of RDD with NGS genetic testing, indicating the difficulty of making a diagnosis before surgery. This extremely rare case offers new references for the understanding of abdominal viscera RDD.

Case of Generalized Tumor-Type Rosai-Dorfman Disease With Sarcoidosis-Like Histological Features and IgG4-Positive Plasma Cells

ABSTRACT

Rosai-Dorfman disease (RDD, also known as sinus histiocytosis with massive lymphadenopathy) is a rare and benign non-Langerhans cell histiocytosis. Skin biopsy usually shows nodular or diffuse dermatitis. Rosai-Dorfman cells (RDD cells) and emperipolesis are the key to diagnosis. RDD cells express S-100 antigen, CD68, CD163, α1-antitrypsin, α1-antichymotrypsin, and ham-56, whereas Langerhans cell markers such as CD1a and langerin are negative. We presented a case of a 55-year-old man with varying sizes of many dark red nodules and lumps over the face, trunk, and limbs for approximately 1 year but without systemic involvement. The results of the laboratory evaluations were notable for an increased level of serum IL-6 and serum IgG4. Histopathological examination showed a diffused dense nodular infiltration of "nude" epithelioid histiocytes with infiltration of minimal lymphocytes and plasm cells around the epithelioid nodules. Immunohistochemistry identified nodular histiocytes being stained strongly positive for S-100 and CD68 but negative for CD1a. Plasma cells showed focally positive for IgG, IgG4, and CD38 and with a ratio of IgG4/IgG >40%. Considering these findings, we believe that our case meets the diagnostic description of "cutaneous Rosai-Dorfman disease" and is, therefore, a rare case with clinical features of multiple tumor-like nodules, sarcoidosis-like histological features, and immunohistochemistry of IgG4-positive plasma cells.

[Rosai-Dorfman disease as a rare cause of a pancreatic mass]

The CT and MRI scans of a 70-year-old male patient revealed a mass in the pancreatic head and a 2.8-cm peripancreatic lymph node. Under steroid therapy the mass did not show regression. Finally, a pancreatoduodenectomy was performed. Histologically, Rosai-Dorfman disease (RDD) was diagnosed. RDD is a rare histiocytic disorder with usually nodal but sometimes also extranodal involvement. Herein we report a rare case of extranodal RDD with intrapancreatic localization.

Rosai-Dorfman disease with renal involvement and associated autoimmune haemolytic anaemia in a 12-year-old girl: A case report

Background

Rosai- Dorfman Disease (RDD) is a benign condition of unknown aetiology which is characterized by non-neoplastic proliferation of histiocytes. Pathophysiology and natural history remain obscure due to the low prevalence of disease. It is known to present with nodal or extranodal involvement and occurrence in the genitourinary system could lead to dreadful complications. RDD is diagnosed by demonstrating emperipolesis on histology and supported by S100 positivity in immunohistochemistry. Treatment is tailored individually and includes expectant monitoring, steroids, surgery, chemotherapy and radiotherapy. Prognosis will be poor if there is involvement of vital organs. We report a rare case of renal Rosai-Dorfman Disease in a 12-year-old girl which also associated with cold type autoimmune haemolytic anaemia (AIHA).

Case presentation

A previously healthy, 12-year-old girl presented with low grade fever and cough over one month. On examination, she was pale, mildly icteric and had a firm mass in the left hypochondrial region.

Her blood count revealed significant eosinophilia, normocytic normochromic anaemia and thrombocytosis. Further laboratory investigations revealed reticulocytosis, positive urine urobilinogen, positive direct antiglobulin test and red blood cell agglutination on blood picture suggestive of autoimmune haemolytic anaemia.

Ultrasound scan of abdomen revealed paraaortic and left side retroperitoneal lymphadenopathy with left renal mass. It was further evaluated by Contrast Enhanced Computed Tomography (CECT). Biopsy was done and that concluded sinus histiocytosis with massive lymphadenopathy (SHML) with positive S100 and CD1a in immunohistochemistry. Child was treated with steroids however there was no significant response as assessed by repeat CT and has been commenced on chemotherapy.

Conclusion

RDD is believed to be due to host immune dysregulation and precise diagnosis is imperative. It should be considered as differential diagnosis in a child presenting with massive lymphadenopathy and AIHA. Association between RDD and AIHA may possibly be explained by abnormal immune response of the host.

Disease Characteristics, Radiologic Patterns, Comorbid Diseases, and Ethnic Differences in 32 Patients With Rosai-Dorfman Disease

OBJECTIVE

Rosai-Dorfman disease (RDD) is a rare and idiopathic nonneoplastic disease of histiocytes that is characterized by lymphadenopathy and extranodal disease. In this study, we documented anatomical preferences, imaging findings, comorbid diseases, and ethnic differences in 32 RDD patients.

METHODS

We conducted a retrospective review of pathologically confirmed cases seen at our institution from 1998 to 2016. These cases were analyzed for (a) anatomical locations, (b) radiologic appearance, (c) comorbid diseases, and (d) differences between ethnic groups.

RESULTS

We found 32 patients with RDD, 18 were women and 14 were men. There were 51 lesions in all patients, 23.5% of which were nodal, involving 11 lymph node regions, and 76.5% were extranodal. Cervical lymph nodes and maxillofacial area were the most common affected nodal and extranodal locations, respectively. Only 4 (12.5%) of 32 patients had pure nodal involvement, whereas 20 (62.5%) of 32 had pure extranodal disease and 8 (25%) of 32 had mixed nodal and extranodal disease.Anatomically, RDD affected multiple organs in our cohort, including the lymphatic system, maxillofacial area (glandular and nonglandular tissues), superficial soft tissue, central nervous system, breast, peritoneum, gastrointestinal tract, and lungs.Radiologically, RDD presentation was variable from an organ to another. However, most lesions were hypermetabolic on 18F-fluorodeoxyglucose positron-emission tomography/computed tomography and isointense on T1-weighted magnetic resonance imaging. Computed tomographic findings were extremely variable between organs.Comorbid diseases were found in 11 patients. Those patients had 17 comorbid diseases; the most common were autoimmune diseases, viral diseases, and cancer.The organ distribution of RDD was slightly different between ethnic groups. The most frequent disease location for African Americans was lymph nodes; for whites, central nervous system and nonglandular maxillofacial (27.3% each); for Asians, lymph nodes, subcutaneous tissue, and nonglandular maxillofacial (25% each); and for Hispanics, lymph nodes and glandular maxillofacial (33.3% each).

CONCLUSIONS

Rosai-Dorfman disease represents a wide-spectrum disease not limited to lymph nodes. Radiologically, RDD has diverse imaging findings. However, most lesions were hypermetabolic on 18F-fluorodeoxyglucose positron-emission tomography/computed tomography and isointense on T1-weighted imaging. Patients with RDD have a high rate of comorbid diseases including autoimmune disease, viral infections, and cancer.

Long-Lasting Follow-Up with Low-Dose Steroid in an 18-Year-Old Male with Rosai-Dorfman Disease

Rosai–Dorfman disease (RDD) is a rare and benign pathology of sinus histiocytosis of unknown etiology. Lymphadenopathy is the predominant clinical manifestation, but diverse organs can also be affected. Histological features involve S-100+ histiocytes with characteristic nuclear features within the enlarged sinusoids of the lymph nodes. The clinical course is unpredictable, but is often benign with spontaneous resolution of disease in most patients. We report a patient with bilateral massive enlargement of cervical, axillary, and inguinal lymph nodes, moderately enlarged spleen, and a weight loss of 15 kg. Excisional biopsy from the cervical lymph node showed that the dilated sinusoids were infiltrated by lymphocytes, plasma cells, and large histiocytes with CD 68 and S-100 protein positive. Due to the slow progression of the disease, oral prednisolone with a body weight of 1 mg/kg was started in March 2016. The steroid dosage has been adjusted many times during the clinical follow-up. After 33 months, steroid treatment resulted in partial shrinkage of lymph nodes, the spleen returned to its normal size, and the patient gained weight. After 38 months of follow-up, no systemic symptoms, sign, or extranodal involvement were detected, and the patient continued with low-dose steroid treatment.

Sonographic features of Rosai-Dorfman disease in the breast: A case report

Rosai-Dorfman disease (sinus histiocytosis with massive lymphadenopathy) is an uncommon histiocytic disease of the lymph nodes. Extranodal presentation, especially in breast parenchymal tissue, is rare. A 54-year-old woman presented with a painful and palpable lump in the right breast. Ultrasonography revealed an irregular, indistinct, hypoechoic mass with a hyperechoic halo. Pathological analysis revealed proliferation of large histiocytes and stromal fibrosis with emperipolesis and positive immunoreactivity for S-100 and CD68. The clinical and radiologic manifestations of Rosai-Dorfman disease may vary, and differentiation from other inflammatory diseases and malignancies is challenging; thus, accurate pathological diagnosis plays an important role in appropriate management.

Rosai-Dorfman Disease: The MD Anderson Cancer Center Experience

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare disorder composed of a proliferation of histiocytes with varied clinical manifestations.

PATIENTS AND METHODS

In this retrospective observational study, we obtained demographic, clinical, and outcome data from the medical records of 10 adult patients with RDD seen in the Department of Lymphoma and Myeloma at MD Anderson Cancer Center between 1995 and 2015.

RESULTS

Patients had a median age of 56 years (range, 20-81 years) with equal gender distribution. Five patients were initially treated with systemic therapy. Five received cladribine as initial therapy or for relapse. Other therapeutic agents included clofarabine, lenalidomide, and steroids. The overall response rate was 80% in patients receiving cladribine, with a median progression-free survival of 29 months. Surgery, radiotherapy, and observation were also treatment options for localized disease. With a median follow-up of 65 months, none of the patients have died.

CONCLUSION

Currently, there is no standard of care for RDD. Treatment should be personalized for each patient depending on the clinical presentation, course of the disease, and prior treatment history. Purine analogues provide excellent responses; however, surgical resection and observation are also suitable for specific cases.

Simultaneous Occurrence of Rosai-Dorfman Disease and Nodal Marginal Zone Lymphoma in a Patient with Sjögren's Syndrome

We present an exceptionally rare case of co-occurrence of Rosai-Dorfman disease (RDD) and nodal marginal zone lymphoma (NMZL) in a 60-year-old Caucasian female with a 20-year course of Sjögren's syndrome (SS). In response to treatment for lymphoma, the patient presented a short positive response, followed by a rapid progression of the disease accompanied by the development of the peripheral facial nerve palsy. We failed to detect Epstein-Barr virus (EBV) in the NMZL/RDD sample by EBV-encoded RNA (EBER) in situ hybridization but identified genomic DNA of EBV by polymerase chain reaction. A second biopsy revealed EBV-positive diffuse large B-cell lymphoma (DLBCL), not otherwise specified. The identical clonal immunoglobulin heavy chain gene rearrangements in the NMZL and DLBCL pointed to their clonal relationship. Though the role of EBV in the pathogenesis of some lymphomas is well-known, there have been only few cases of EBV-induced transformation of low-grade B-cell lymphoma into high-grade lymphoma and no cases of a patient with an NMZL background. To our knowledge, this is the first report of a concomitant occurrence of RDD and NMZL in a SS patient.

Rosai-Dorfman disease: Ultrasonography and histopathology study of a soft tissue mass in the forearm

Rosai-Dorfman disease (RDD) is uncommon in daily practice, but needs to be ruled out in rheumatologic conditions to elucidate a wide differential diagnosis. Beside its typical presentation, soft tissue masses can be easily seen in our Rheumatology clinics. Ultrasonography widely extended in our specialty, could also play a role in the diagnosis, to end up with the histological confirmation of the disease.

A case report of Rosai-Dorfman disease with kidney involvement

Rosai-Dorfman disease (RDD) is a rare histiocytic disorder of unclear etiology, which commonly presented with the enlargement of lymph nodes of the neck and the head. Here, we report an unusual case of 77-year-old male patient presenting with left kidney lesion with several small enlarged lymph nodes around the abdominal aorta. The diagnosis of left kidney cancer was suspected and the patient underwent left laparoscopic exploration and lymph node biopsy. Only saponification of the renal surrounding fat and enlargement of the left renal pedicle and 5 abdominal aortic lymph nodes were found; no kidney cancer was found. Surrenalectomy and lymphadenectomy dissection were then performed and the left kidney was retained. Intraoperative frozen and postoperative pathology indicates Rosai-Dorfman disease. RDD with kidney involvement is uncommon, and its x-ray imaging appearances are atypical, and often resemble kidney cancer leading to kidney loss. A systematic literature review was also performed to investigate the x-ray imaging and treatment features of this disease.

Multimodality imaging-based evaluation of Rosai-Dorfman disease in the head and neck: A retrospective observational study

Rosai-Dorfman disease (RDD) is an uncommon benign entity characterized histologically by lymphatic sinus dilatation due to histiocyte proliferation. This study was performed to delineate its imaging features, reviewed retrospectively in 12 patients (8 women and 4 men, mean age 58.2 years [range 27-84]) with pathologically confirmed RDD in the head and neck. The location, involvement, and imaging characteristics (CT, magnetic resonance imaging (MRI), and PET/CT) of all lesions were evaluated. Signal intensity on MRI images was compared to gray matter (orbital RDD) and adjacent muscle (sinonasal and cervical RDD). RDD in the head and neck involved multiple sites, primarily the sinonasal cavity (n = 7), neck (n = 3), and orbit (n = 1), with one case of simultaneous involvement of the sinonasal cavity, orbit, and neck. With sinonasal involvement, MRI signal intensity of the involved areas was isointense or slightly hyperintense relative to adjacent muscle on T1WI images and heterogeneous on T2WI images; with lacrimal involvement, it was isointense relative to gray matter on T1- and T2-weighted images; and with neck involvement, it was isointense relative to muscle on T1WI images and relatively hyperintense on T2WI images, with homogenous postcontrast enhancement in all sites of involvement. The lesions on CT were observed as enhancing masses with or without bony destruction. PET/CT showed hypermetabolism in one lesion in the neck. RDD is a rare disorder with multiple sites of involvement in the head and neck. Concomitant cervical lymphadenopathy with extranodal masses assisted by multimodal imaging may be useful in the diagnosis of RDD.

Mutually exclusive recurrent KRAS and MAP2K1 mutations in Rosai-Dorfman disease

Rosai-Dorfman disease is a histiocytic disorder with a poorly defined pathogenesis. Recent molecular studies have revealed recurrent mutations involving genes in the MAPK/ERK pathway in Langerhans cell histiocytosis and Erdheim-Chester disease. However, cases of Rosai-Dorfman disease have rarely been assessed. We performed next-generation sequencing to assess 134 genes on 21 cases of Rosai-Dorfman disease, including 13 women and 8 men with a median age of 43 years (range, 3-82). In all, 13 had extranodal, 5 had nodal, and 3 had coexistent nodal and extranodal disease. The head and neck region was the most common area involved (n=7). Mutation analysis detected point mutations in 7 (33%) cases, including KRAS (n=4) and MAP2K1 (n=3). No mutations were identified in ARAF, BRAF, PIK3CA, or any other genes assessed. Immunohistochemistry demonstrated p-ERK overexpression in 3 cases, all harboring MAP2K1 mutations. Patients carrying mutated genes were younger (median age, 10 vs 53 years, P=0.0347) with more pediatric patients (4/7 vs 1/14, P=0.0251). The presence of mutations correlated with location being more common in the head and neck region; 6/7 (86%) mutated vs 1/14 (7%) unmutated cases (P=0.0009). All 5 (100%) mutated cases with available staging information had a multifocal presentation, whereas only 3/11 (27%) unmutated patients had multifocal disease (P=0.0256). Treatment information was available in 10 patients, including radical resection (n=4), resection and radiation (n=3), and cladribine-based chemotherapy (n=3). With a median follow-up of 84 months (range, 7-352), 7 remained in clinical remission and 3 had persistent disease. No correlation between mutation status and clinical outcome was noted. In summary, we detected mutually exclusive KRAS and MAP2K1 mutations in one-third of cases of Rosai-Dorfman disease suggesting this subgroup are clonal and involve activation of MAPK/ERK pathway. Our data contribute to the understanding of the biology of Rosai-Dorfman disease and point to potential diagnostic and therapeutic targets.

Cutaneous involvement of pre-existing Rosai-Dorfman disease via post-herpetic isotopic response

We report the case of a patient with a long-standing history of extranodal, sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease) and no evidence of original cutaneous involvement as well as a history of herpes zoster of the left flank with post-herpetic neuralgia who went on to develop multiple, round-to-oval, red-brown, atrophic macules and thin papules at the sites of herpes zoster scars on the left flank. Histopathology showed a dense nodular infiltrate of lymphocytes with some plasma cells and numerous large pale-staining histiocytes (S100+/CD68+), consistent with Rosai-Dorfman disease. This case showed exclusively cutaneous involvement, as demonstrated by otherwise normal physical examination, laboratory evaluation and imaging. This is the second reported case of Rosai-Dorfman disease occurring at the site of zoster scars, and to our knowledge this represents the first case report of cutaneous involvement of pre-existing Rosai-Dorfman disease via post-herpetic isotopic response (Wolf's isotopic response).

Successful Treatment of Recurrent Autoimmune Cytopenias in the Context of Sinus Histiocytosis With Massive Lymphadenopathy Using Sirolimus

Sinus histiocytosis with massive lymphadenopathy (SHML), or Rosai-Dorfman disease (RDD), is a non-neoplastic, lymphoproliferative disorder that usually resolves spontaneously or with minimal conventional chemotherapy. Rarely, SHML can be associated with autoimmune findings. Such cases are often treatment resistant and have high rates of morbidity and mortality. We present a case of a patient with long-standing autoimmunity in the context of SHML, dependent on standard-treatment until he was transitioned to novel monotherapy with sirolimus. Sirolimus treatment resulted in a complete remission, now sustained after discontinuation of all treatments for over 23 months, with no observable long-term sequelae.

Rosai Dorfman disease diagnosed by fine-needle aspiration cytology in a young man with HIV infection

RDD (Rosai Dorfman disease) is a rare and benign histiocytic proliferative disorder of unknown etiology. FNAC (Fine-needle aspiration cytology) is a useful and reliable tool for the diagnosis of RDD, and as such, biopsy is avoidable.