Splenic hamartoma with bizarre stromal cells.

Splenic hamartoma is a rare entity characterized by disorganized red pulp tissue in the absence of interspersed white pulp. We report 3 cases with scattered bizarre stromal cells, a feature not previously reported in the literature. The patients were adults who presented with abdominal pain (2 cases) or were incidentally found to have a splenic mass (1 case). The lesion was solitary, circumscribed, and unencapsulated, comprising disorganized slit-like, tubular, ectatic or cavernous vascular channels. There was a loose stroma that contained lymphocytes, plasma cells, siderophages, and fibrin exudate. Scattered haphazardly were isolated bizarre large cells with oval, convoluted, or multilobated nuclei; pale or smudged chromatin; and scanty cytoplasm. Mitotic figures were not found. The bizarre cells were negative for lymphoid, dendritic cell, histiocytic, myeloid, endothelial, epithelial, and melanocytic markers. Only rare bizarre cells stained for desmin in 1 case. It is important to recognize this morphologic variant of splenic hamartoma in order not to misinterpret the bizarre cells as being indicative of a malignancy.