Metastatic Prostate Adenocarcinoma in Primary Lung Adenocarcinoma: An Unusual Case Report and Literature Review

Abstract

Tumor-to-tumor metastasis (TTM) is a rare condition in which one tumor metastasizes into another tumor. Based on the literature, the most common donor of TTM is lung and the most common recipient is kidney. Here we reported a rare case that has the metastatic prostate adenocarcinoma in primary lung adenocarcinoma. According to our knowledge, it is the first report in the English literature in the last 20 years. The patient is a 74-year-old male with the history of prostate cancer, which was treated by external beam radiation and androgen deprivation therapy. Nine years after treatment, he was found to have multiple metastatic bone lesions and androgen deprivation therapy was given again. Eleven years after initial diagnosis, the patient present with short of breath and CT showed a right upper lobe nodule and an enlarged right hilar lymph node. Both the lung nodule and the hilar lymph node were biopsied. The hilar lymph node was positive for metastatic prostate adenocarcinoma. Interestingly, the lung nodule showed two different histological components intermixed with each other. The majority of tumor cells formed glandular structure and were immunostained positive for CK7, TTP-1 and Napsin A, compatible with primary lung adenocarcinoma. Some individual and small cluster of cells were negative for the above markers, but highlighted by PSA, PSAP and racemase (AMACR/P504S) immunostain, which were consistent with metastatic prostate adenocarcinoma. The patient was scheduled to be treated with stereotactic body radiation therapy (SBRT), but he declined. His current condition is stable at the most recent follow-up.

[N A J Med Sci. 2016;9(3):127-131.   DOI:  10.7156/najms.2016.0903127]