Splenic hamartoma: immunohistochemical and ultrastructural profile of two cases.

Splenic hamartoma (SH) is a rare, benign lesion. We present 2 cases, both in females (2 and 30 years, respectively) with multiple urinary tract infections, and left upper quadrant abdominal pain. Immunohistochemical staining with factor VIII displayed intense diffuse staining in the SH with corresponding weak staining in the adjacent spleen. CD31 showed a reverse pattern from that of factor VIII. CD34 staining pattern was identical in both the spleen and the SH. Ultrastructurally, the SH showed endothelial cells with relatively empty cytoplasm, scattered Weibel Palade bodies, and lining by basement membrane surrounded by fibrous long-spacing collagen. Our study highlights the unique immunohistochemical profile of SH. The ultrastructural features are interesting, although their diagnostic significance remains to be confirmed in future studies.