[Prostate Carcinoma Mimics Lung Carcinoma: A Case Report].

A PSA-negative, advanced adenocarcinoma of the prostate is a rare finding. Expression of thyroid transcription factor-1 (TTF-1) in the tumour in combination with a previous medical history of lung adenocarcinoma could complicate the final diagnosis. To the best of our knowledge, we present the second case of a TTF-1-positive, acinar adenocarcinoma of the prostate.We present the case of a 65-year-old male with surgically treated lung adenocarcinoma; 3 years later we diagnosed adenocarcinoma of the bladder and prostate. Although our initial assumption was that the patient had metastatic lung carcinoma in the bladder and prostate, a further immune histochemical analysis of the carcinoma with Napsin A, CK7 and CK20, along with the evaluation of the clinical manifestations, led us to the diagnosis of primary adenocarcinoma of the prostate.