Metastatic Tumors in Testis : Pitfalls
Metastatic Carcinoma in the Testis - Diagnostic Pitfalls: Metastases from prostate, lung, kidney, stomach, colon, urinary bladder, skin (melanoma), thyroid (medullary carcinoma), pancreas, liver, and well-differentiated neuroendocrine tumor (carcinoid) may mimic primary testicular tumors. Metastatic carcinoma or melanoma may be mistaken for embryonal carcinoma, Leydig cell tumor, or Sertoli cell tumor. Metastatic well-differentiated neuroendocrine tumor (carcinoid) may be diagnosed as primary testicular carcinoid. Metastatic melanomas may have foamy cytoplasm and mimic Leydig cell tumor. Metastatic prostate cancer can show intratubular growth or involve rete testis and mimic primary testicular neoplasms or carcinoma of rete testis. Features favoring testicular metastasis over primary testicular malignancy include: age > 50 years, multifocality and bilaterality, history of a primary malignancy at another location, uncommon pattern not normally seen in a primary testicular tumor, lymphovascular invasion, lack of germ cell neoplasia-in-situ, and intertubular growth pattern. Elevated serum AFP or beta-hCG favor primary testicular germ cell tumor over metastases. The image shows another example of metastatic prostatic adenocarcinoma in the testis. The tumor cells appear to recapitulate architecture of Gleason pattern 4.