Rosai-Dorfman disease (sinus histiocytosis with massive lymphadenopathy) of the pancreas: first case report.

Rosai-Dorfman Disease is a histiocytic proliferative disorder which primarily affects lymph nodes. Extranodal involvement occurs in about one half of the patients and the head and neck area represents the region most commonly involved. We present the case of a 48 year-old female who was found with a pancreatic mass during evaluation for abdominal pain. She underwent a distal pancreatectomy and splenectomy. Her pathology showed sinus histiocytosis with massive lymphadenopathy (SHML) involving the pancreas and lymph nodes and focally the spleen. The histiocytes characteristically contained one or more viable lymphocytes in the cytoplasm. The lymphocytes had penetrated the cytoplasm in a process known as "emperipolesis", where the lymphocytes continued to have free movement in the histiocyte. The histiocytic cells were positive with S-100 protein and CD68. Rosai-Dorfman Disease (SHML) can affect the peripancreatic lymph nodes with possible secondary pancreatic involvement and present as a pancreatic mass.