Epithelioid sarcoma of the penis. Clinicopathologic study of a tumor with myogenic features and review of the literature concerning this unusual location

Soft tissue tumors of the penis are uncommon. We report here the clinicopathologic features of a penile epithelioid sarcoma (ES), review the literature concerning this unusual location and focalize our attention on its differentiation. The 34-year-old patient was admitted for abrupt urinary retention due to the growth of a firm and painful plaque on the left side of the shaft, three years previously clinically diagnosed as Peyronie's disease. Magnetic nuclear resonance revealed an infiltrating lesion of both corpora cavernosa. Histology of bioptic fragments showed a nodular malignant spindle and epithelioid cell tumor with focal necrosis and relatively high mitotic rate. Based on the immunohistochemical data (cytokeratin+, vimentin+, EMA+, CD34+, and S100-), the diagnosis of ES was strongly considered. Penectomy was undertaken and the diagnosis confirmed by both light and ultrastructural microscopy. The 22 month follow-up was free of recurrences and metastases. Although not dissimilar from the 10 previously described ES of the penis in terms of natural history and histology, the tumor reported here showed myogenic features as revealed by both immunohistochemistry (immunoreactivity for muscle specific actin) and ultrastructure (intercellular junctions, discontinuous basal lamina, pinocytotic vesicles and thin filaments with intercalated dense bodies). Although previously observed in ES of other sites, this feature has never been established in ES of the penis.