Fine needle aspiration diagnosis of Rosai-Dorfman disease in an osteolytic lesion of bone.

Sinus histiocytosis with massive lymphadenopathy (SHML) or Rosai-Dorfman disease (RDD) is an uncommon but well-defined benign self-limited clinicopathological entity. It mainly involves lymph nodes. Extranodal involvement is seen in up to 43% of cases, with the most common location in the head and neck region. Primary RDD occurring in the bone is rare with only twelve cases reported in the literature to date, all diagnosed on histology except one by fine needle aspiration (FNA) cytology. We report a case of RDD diagnosed by FNA cytology in a 28 year-old female presented as an osteolytic lesion of superior pubic ramus where the differential diagnosis included a sarcoma and lymphoma. Based on the cytologic findings, a diagnosis of a RDD was considered during the rapid FNA on site with no clinical history provided. The diagnosis of RDD was further confirmed by immunohistochemical stains and histology diagnosis. Our findings show that even in the absence of a clinical history, FNA is a less invasive and a very reliable tool for the diagnosis of SHML (RDD).