Vasitis nodosa--a site of arrest of malignant germ cells

A 40-year-old man, with a history of vasectomy 11 years previously, presented with a tumour in his right testis. At orchidectomy a seminoma was found, together with a nodule on the vas deferens. Histological examination of this area in the vas identified the lesion of vasitis nodosa and also showed it to be the site of proliferating germ cells. The pathogenesis of this lesion is discussed.