Lipomatous hemangiopericytoma of the corpus spongiosum: a case report and review of the literature.

BACKGROUND

Hemangiopericytoma (HPC) is an uncommon soft tissue tumor arising from pericytes. The urogenital system is rarely affected.

METHODS

The review of the literature used the PubMed database which was searched up to March 2015.

RESULTS

Herein, we report the first case of lipomatous HPC of the corpus spongiosum in a 37-year-old man in China. The lesion presented as a quickly growing mass. Contrast enhanced CT showed a heterogeneous fatty mass with a multifocal enhancing soft-tissue component. Microscopically, the neoplasm was composed of spindle cells, a mature fat component and collagenous stroma. The mitotic index was low at 1 to 3 mitoses per 10 high-power fields. Immunohistochemically, STAT6, Bcl-2, CD99 and CDK4 were positive; CD34 and SMA were negative. The mature adipocytes were positive for S-100. Ki-67 expression was found in approximately 5% of the tumor cells. Surprisingly, there was a diffuse and strong nuclear expression of MDM2, but, no amplification of MDM2 was demonstrated by FISH. An adequate excision of the tumor was performed.

CONCLUSION

No local recurrence or distant metastases occurred during the 18-month follow-up. In view of the unpredictable biological behavior of this tumor, a long follow-up period is mandatory.