Rosai-Dorfman disease manifesting as multiple subcutaneous nodules. Report of a case with diagnosis on a fine needle aspirate.

BACKGROUND: Rosai-Dorfman disease (RDD), or sinus histiocytosis with massive lymphadenopathy, is a benign, self-limiting histiocytic proliferative disorder commonly involving the lymph nodes. Extranodal disease occurs in about 40% of cases, and the sites involved are skin, nasal cavity, paranasal sinuses, eyelids, orbit, bone and central nervous system. CASE: A case of RDD presented as subcutaneous nodules and was diagnosed on a fine needle aspirate. The aspirate revealed numerous histiocytes with phagocytosis of lymphocytes, plasma cells and neutrophils. Surgical biopsy and immunocytochemical stain for S-100 protein confirmed the diagnosis. Later the patient developed lymphadenopathy and involvement of the nasal septum.
CONCLUSION: Extranodal RDD can be diagnosed by FNAC in conjunction with immunocytochemistry.