Cytomorphology of Sinus Histiocytosis with Massive Lymphadenopathy (Rosai-Dorfman Disease): A Report of Two Cases

Rosai–Dorfman disease (RDD), a rare, benign, selflimiting histiocytic proliferative disorder, can be encountered in both nodal and extranodal locations, and fine needle aspiration (FNA), a simple, accurate and economic tool, has been widely used for the diagnosis of superficial and deep-seated lesions. Familiarity with the cytomorphologic features of RDD is important as prognosis and treatment are quite different from other benign or malignant diseases for which it may clinically masquerade. We report two cases of Rosai–Dorfman disease, one with typical and other with an unusual