Lymphangitic Carcinomatosis Presenting as Cough: A Case of Occult Metastatic Prostate Adenocarcinoma.

Background: Lymphangitic carcinomatosis (LC), a hallmark of advanced metastatic cancer with a poor prognosis, primarily impacts the lymphatic system of the lungs, manifesting as progressive breathlessness, cough, or hemoptysis. While prostate cancer commonly metastasizes to bones and regional lymph nodes, lung involvement is rare. This case features a patient in generally good health who presented with an insidious dry cough, leading to a diagnosis of Stage 4 prostatic adenocarcinoma with rare lymphangitic spread to the lungs. Case Presentation: A 70-year-old male in good health presented with chest tightness, a dry cough, and sudden left testicular swelling. Imaging revealed interstitial lung markings, severe left hydronephrosis, and prostatomegaly. A prostate biopsy confirmed adenocarcinoma. A PET-CT scan raised significant concern for LC, prompting the initiation of urgent inpatient chemotherapy with docetaxel. Conclusion: LC is a metastatic pattern commonly associated with solid tumors, particularly breast, gastric, and lung cancers. Its occurrence in prostate cancer is exceptionally rare. This condition is typically linked with advanced disease and a poor prognosis, often serving as a critical indicator of an underlying malignancy that may otherwise go undetected.