Atypical metastases from prostate cancer: 10-year experience at a single institution

OBJECTIVE. The purpose of the study was to retrospectively review the frequency, sites, and patterns of atypical metastases from prostate cancer and to determine whether any correlation exists between the atypical sites and biochemical or histologic variables. MATERIALS AND METHODS. All available imaging studies of 620 consecutive patients with biopsy-proven prostate carcinoma seen at our institute between 1999 and 2009 were reviewed. Eighty-two patients (mean age, 72 years; age range, 58-87 years) with atypical sites of metastases were identified. Patients were separated into groups on the basis of the presence or absence of concurrent osseous metastasis and high or low Gleason grade, and metastatic patterns were compared using the Fisher exact test. The maximum prostate-specific antigen (PSA) level for each patient was recorded and correlated with metastatic pattern using the Mann-Whitney test. RESULTS. The most frequent sites of atypical metastases were the lungs and pleura (40%, 33/82), liver (37%, 30/82), supradiaphragmatic lymph nodes (34%, 28/82), and adrenal glands (15%, 12/82). Supradiaphragmatic lymphadenopathy was more common in patients with osseous metastases (45%, 25/56) than in patients without concurrent osseous involvement (12%, 3/26; p < 0.05). There was no significant correlation between the other atypical metastatic sites and osseous metastases. Abdominal visceral metastasis occurred more frequently in patients with a high Gleason grade (25/43, 58%) than in patients with a low Gleason grade (9/29, 31%; p < 0.05). There was no significant correlation between metastatic pattern and PSA level. CONCLUSION. The lungs and pleura, liver, supradiaphragmatic lymph nodes, and adrenal glands are the most common extranodal metastatic sites of prostate cancer. Supradiaphragmatic lymphadenopathy was strongly associated with concurrent osseous metastases.