A Case of Rosai-Dorfman Disease Presenting as an Isolated Pleural Plaque.

Rosai-Dorfman disease (RDD) is a rare non-Langerhans histiocytic disorder primarily involving lymph nodes. Extranodal RDD has a heterogenous presentation, and isolated pulmonary involvement is rare. We report the only case of RDD presenting as an isolated pleural mass. Our patient was a 55-year-old female with multiple comorbidities who presented with chest pain. Imaging revealed an enlarging pleural-based lesion. She underwent resection of the pleural mass, showing an atypical histiocytic infiltrate in a prominent background of collagenous fibrosis. Immunohistochemistry shows CD1a-negative and S100-positive atypical histiocytic cells demonstrating emperipolesis, confirming the diagnosis of RDD. She is currently on six-month CT surveillance with no recurrence of the disease. This case highlights the unique pulmonary presentation of RDD. It also underscores that observations may be appropriate in isolated asymptomatic pleural involvement cases.

Rathinam A ，Gupta S ，Khanam R ，Sahai T ... -  《Cureus》

Differential diagnosis in Rosai-Dorfman disease: A rare case of isolated hepatic presentation mimicking a metastatic tumor with positive 18-FDG uptake.

Rosai-Dorfman disease (RDD) is also called sinus histiocytosis with massive lymphadenopathy, and it is caused by a histiocytic disorder with unclear etiology. It usually involves cervical lymph nodes, but it may also present with extranodal involvement. We report a rare condition of isolated hepatic RDD without nodal involvement, clinically manifested with three-month abdominal pain and tenderness of the right hypochondrium. CT- and PET-CT scans were compatible with a secondary lesion from an unknown primary tumor. Therefore, the patient underwent an atypical liver resection. Immunohistochemistry and histological results were compatible with a diagnosis of RDD. RDD is characterized by phenomena of emperipolesis, histiocytic proliferation and positive immunostaining for CD14, CD68 and S-100 protein. Cases of isolated gastrointestinal localization of RDD are particularly rare, especially in the liver. Instrumental exams might confuse RDD with other malignancies. RDD is a rare entity, which might be misdiagnosed using PET-CT due to its similarities with malignant tumors. An accurate multidisciplinary approach may help to clear diagnostic clues of this uncommon disease.

Gazia C ，Giordano L ，Diodoro MG ，Compalati I ，Avantifiori R ，Grazi GL ... -  《-》

Rosai-Dorfman disease involving gallbladder and liver-Report of a case.

Rosai-Dorfman disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is a rare histiocytic disorder of unclear etiology. Lymphadenopathy commonly affects the lymph nodes of the neck and the head, but extranodal involvement has been observed too. We describe an unusual case of RDD with involvement of the gallbladder, liver and cystic lymph node, clinically manifested as an exacerbated cholecystitis. The patient underwent a cholecystectomy with atypical liver resection because the finding was macroscopically suspected of gallbladder cancer. The diagnosis of RDD was confirmed by immunohistochemical study. Histological features of RDD include histiocytic proliferation, emperipolesis and positive immunostaining for S-100 protein and typically negative for CD1a. Gastrointestinal localization of RDD, especially in the liver and pancreas, is extremely rare. Typically, the liver is affected as a part of systematic spread of RDD. We have not found reports for involvement of the gallbladder. The presented case is valuable due to its rarity and difficulty in differential diagnosis.

Arabadzhieva E ，Yonkov A ，Bonev S ，Bulanov D ，Taneva I ，Pirdopska T ，Terziev I ，Dimitrova V ... -  《-》

Pure Cutaneous Rosai Dorfman Disease: An Uncommon Location for a Rare Histiocytic Proliferative Disorder.

RosaiDorfman disease (RDD) is a rare, self-limiting disease of uncertain etiology involving lymph nodes as well as extranodal sites. Isolated or pure cutaneous RDD (PCRDD) without lymph node involvement is very unusual accounting for only 3% of all described cases of RDD. The clinical features of PCRDD are quite different from RDD according to the literature on extranodal RDD, thereby emphasizing that PCRDD is a distinct clinical entity. Histopathology remains the gold standard for the diagnosis of both systemic and PCRDD with the presence of characteristic emperipolesis observed in histiocytes while immunohistochemistry (IHC) (S100, CD 68 positive, and CD 1a-negative) serves as a useful adjunct. We hereby report a case of a 36-year-old female who presented with a tender, indurated plaque on the left forearm with a clinical differential diagnosis of borderline tuberculoid leprosy/sarcoidosis and lupus vulgaris. However, on histopathology, a diagnosis of RDD was performed and confirmed on IHC. This case highlights the need to create awareness among young pathologists and clinicians about PCRDD to prevent overzealous treatment.

Jain M ，Pujani M ，Sidam D ，Wadhwa R ，Passi S ，Uikey D ... -  《-》

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.

Amir B ，Amir A ，Sheikh S 《-》