A Case of Cavitary Lung Metastasis From Prostate Cancer

Abstract

A 79-year-old man was found to have multiple nodules in the lung fields on chest computed tomography. Metastatic lung cancer was suspected; however, the primary site remained elusive. After 1 year of follow-up, both the nodules had enlarged. After 2 years, one of the nodules continued to enlarge; however, the other nodule cavitated and decreased in size. Concomitantly, the previously observed fluorodeoxyglucose uptake in the cavitated nodules disappeared. A comprehensive search for the primary cancer included a thoracoscopic lung biopsy which revealed that these nodules were metastatic lung lesions from prostate cancer. Pathological examination revealed necrosis within these metastatic lesions. To date, only three case reports of cavitary lung metastases from prostate cancer have been published; however, no explanation has been provided for the pathological mechanism of cavitation. To our knowledge, this is the first case to provide a potential explanation for cavitation in metastatic lung lesions from prostate cancer.

Keywords: FDG‐PET; cavitary lung metastasis; necrosis; prostate cancer; thoracoscopy.

FIGURE 1

Chest computed tomography (CT) scan (A1–A3, B1–B3, and C1–C3) and fluorodeoxyglucose‐ positron emission tomography (FDG‐PET) findings (D, E). Two years before referral to our institution, a chest CT revealed nodular opacities in S6 and S8 of the left lower lobe (A1–A3). A PET scan showed FDG uptake within the nodules (SUVmax 2.34 for S6 and 2.40 for S8) (D). A follow‐up chest CT scan after 1 year showed that both nodules were enlarged (B1–B3). A chest CT scan after 2 years showed that the S8 nodule had enlarged in size; however, the S6 nodule had cavitated and decreased in size (C1–C3). A PET scan showed FDG uptake in the S8 nodule (SUVmax 4.26) but not in the S6 nodule (E).

FIGURE 2

Pathological findings of the S6 (A–C) and the S8 lesions (D, E) excised under thoracoscopy. Both specimens showed adenocarcinoma. The nodule in S6 had adenocarcinoma in part, surrounded by necrotic tissue or areas of tissue loss (haematoxylin and eosin, A 20×, B 200×). Figure C shows a magnified image of the cavity wall and the surrounding tissue loss area (haematoxylin and eosin, 100×). The cavity wall shown on the left side of the figure is part of the pleura. It is thought that this tissue loss area originally occupied a much larger space, as seen on CT, but was reduced by deformation during removal from the thorax. The nodule in S8 was mostly an adenocarcinoma (haematoxylin and eosin, D 40×), but focal areas of necrosis were observed in the magnified image (haematoxylin and eosin, E 100×).