Sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease)--imaging manifestations of renal involvement.

A 23-year-old lady presented with abdominal fullness and distension as well as large abdominal masses in physical exam. Upon ultrasonographic evaluation, two large space occupying lesions anterior to kidneys, with no clear distinction from renal tissue, as well as bilateral hydronephrosis were found. The findings were confirmed by MRI. Histopathological analysis of renal masses and lymph nodes showed proliferation of histiocytes mixed with occasional multinucleated giant cells, immunostaining of which was positive for S-100 and CD68. We present renal scintigraphy features of this rare case of renal sinus histiocytosis with massive intraabdominal lymphadenopathy (Rosai-Dorfman disease).