A patient has a history of treated prostate cancer, Gleason 9, and underwent a Ga-68 PSMA scan for a
rising PSA level, 14.3ng/ml. Recent bone scan and MR prostate were negative for disease. Scan showed a
PSMA-avid wel-circumscribed rounded lesion in lung with PSMA-avid mediastinal nodes, SUV range
11.6-12.6. Based upon these images, which is the LEAST likely diagnosis - lung metastases from adenocarcinoma of the prostate, primary lung cancer, lung metastases with neuroendocrine transdifferentiation, or active tuberculosis?
Scan showed PSMA avid well circumscribed rounded lesion in lung with PSMA avid mediastinal nodes, SUV range 11.6-12.6.
Ga-68 PSMA positive metastases from prostate cancer
Neuroendocrine trans-differentiation has been identified as a main factor for the loss of PSMA-expression in visceral metastases. Neuroendocrine prostate cancer cells do not express generic prostate cancer biomarkers such as P501S, PSMA, and PSA. Other variants of prostatic malignancies that may not typically express PSMA include poorly differentiated.
Pyka T, Weirich G, Einspieler I, et al. 68Ga-PSMA-HBED-CC PET for Differential Diagnosis of Suggestive Lung Lesions in Patients with Prostate Cancer. J Nucl Med. 2016;57:367–371.
Damjanovic J, Janssen JC, Furth C, et al. 68 Ga-PSMA-PET/CT for the evaluation of pulmonary metastases and opacities in patients with prostate cancer. Cancer Imaging. 2018 Dec;18(1):20