Fine Needle Aspiration Biopsy of Splenic Hamartoma with Bizarre Stromal Cells: a Case Report

Background: Splenic hamartoma is a rare benign "tumor" with disorganized red pulp tissue without white pulp elements. Recently described cases show bizarre stromal cells. Splenic hamartoma has only rarely been described cytologically; the bizarre stromal variant has not been reported.

Case: A 64-year-old woman with history of low-grade malignant fibrous histiocytoma had an isolated, solitary lesion with fluorodeoxyglucose avidity in the spleen on positron emission tomography imaging, and computed tomography-guided fine needle aspiration biopsy was performed. Smears were cellular with large cohesive fragments of spindled to ovoid cells with intermixed bizarre large cells present singly in the background and within groups. Cell fragments possessed a variable proportion of spindle to ovoid cells. The bizarre large cells had single or multiple round, oval or distorted nuclei with granular chromatin. Cell block mirrored the smear pattern, and the bizarre large cells were negative by immunohistochemistry. Malignant spindle cell neoplasm was favored. After splenectomy, splenic hamartoma with bizarre stromal cells was diagnosed.

Conclusion: Splenic hamartoma with bizarre stromal cells is a challenging diagnosis cytologically. In the spleen, it should be considered in the differential diagnosis of entities with bizarre large cells in a background of spindled elements.