A case of occult prostate cancer identified by a solitary pulmonary metastasis as the first presentation

Abstract

Background : Exclusive lung metastasis from prostate cancer is a rare event. In addition, occult prostate cancer identified by lung metastasis as the first presentation is extremely rare. We report herein on a case of prostate cancer with a lung metastasis detected during a follow-up study on gall bladder carcinoma.

Case : A 75-year-old man had undergone an extended cholecystectomy for gall bladder carcinoma 4 years previously. Chest CT revealed small nodular shadows in the left lung. This mass lesion was considered to be a single metastatic deposit from the previous gall bladder carcinoma. Partial resection of the lung by video assisted thoracic surgery was performed. Histological analysis revealed a homogeneous cribriform growth pattern of columnar cells with prominent nucleoli and no stromal components. These features were not consistent with primary lung cancer and metastasis from gall bladder cancer but metastasis from another organ. Detailed histological and immunohistochemical analysis and high serum PSA value were consistent with prostatic origin. A prostate needle biopsy revealed adenocarcinoma (Gleason score 4+4=8). Extensive clinical and radiological examinations revealed no metastasis in organs other than the lung.

Conclusion : We reported this case of occult prostate cancer identified by a solitary pulmonary metastasis as the first presentation to draw attention to a potential cause of diagnostic error.