Cytogenetic support for primary prostatic cancer in a patient presenting with a soft tissue mass in the leg

A 65-year-old man presented with a soft tissue mass in the leg, clinically suspect of a sarcoma. Histologic examination suggested a metastatic adenocarcinoma of the prostate, which could not be confirmed by immunohistologic studies. However, cytogenetic analysis strongly supported this diagnosis. A primary prostatic carcinoma was indeed found and the patient died of widely disseminated disease. These findings illustrate the significance of chromosomal analysis in the search for a primary tumor in patients with an unknown primary.