Massive localized lymphedema of the male external genitalia: a clinicopathologic study of 6 cases.

Massive localized lymphedema is a reactive pseudotumor strongly associated with obesity. The tumor most commonly presents as pendulous masses in the lower limbs with only 3 reported cases involving external male genitalia. In this study, we report an additional 6 cases localized to the external male genitalia. The cases were retrospectively identified from the surgical pathology database of the Johns Hopkins Hospital. All 6 patients were obese (5 presented with diffuse scrotal edema and 1 with a penile mass). In all cases, the clinical impression was of a benign chronic process developing over 3 months to 1 year. All 3 cases from outside institutions were referred with benign pathologic diagnoses. The lesions ranged in size from 4 to 55 cm. Microscopically, all cases exhibited stromal fibrosis and edema, multinucleated stromal cells, perivascular chronic inflammation, and lymphangiectasia. Entrapped fat was a minor feature and seen in only 3 cases. Variable hyperplasia and hypertrophy of dartos muscle were noted in 6 lesions. Three cases showed prominent microvascular proliferation around the edge of individual dartos muscle bundles. In summary, diagnosis of massive localized lymphedema requires appropriate correlation between clinical and microscopic findings. Lesions in the male external genitalia share many microscopic findings with massive localized lymphedema at other sites, although entrapped adipose tissue is not prominent. Additional, although not specific, findings include variably hyperplastic and hypertrophic dartos muscle and capillary neoangiogenesis at the interface between smooth muscle bundles and stroma.