99mTc-PSMA and 99mTc-FAPI-46 Uptake in Pulmonary Lymphangitic Carcinomatosis: A Rare Form of Metastasis in Prostate Cancer Patient, Responding to Modified Treatments.

This case report presents a rare instance of pulmonary lymphangitic carcinomatosis (PLC) in a prostate cancer patient, showcasing uptake of 99mTc-prostate-specific membrane antigen and 99mTc-fibroblast activation protein inhibitor-46 on imaging scans. A 70-year-old man with elevated serum prostate-specific antigen (PSA) levels exhibited respiratory symptoms and was diagnosed with widespread skeletal and pulmonary metastases. Following taxane-based chemotherapy and androgen deprivation therapy, imaging revealed decreased uptake and improvement in clinical symptoms, indicating treatment response. PLC in prostate cancer is exceptionally rare, with only limited documented cases. This report highlights the diagnostic value of 99mTc-prostate-specific membrane antigen and 99mTc-fibroblast activation protein inhibitor scans in identifying PLC and monitoring treatment response, offering insights into the management of this challenging condition.