Unveiling the Unexpected: Lung Adenocarcinoma Presenting With Penile Mondor's Disease and Multiple Thrombotic Complications.

Penile Mondor's disease (PMD) is a rare condition characterized by thrombophlebitis of the superficial dorsal vein of the penis. While typically considered a benign and self-limiting condition, we present an unprecedented case where PMD was the initial presenting symptom of lung adenocarcinoma. This case report describes a 46-year-old Japanese man who presented with PMD and was subsequently diagnosed with stage IVA lung adenocarcinoma. The patient's clinical course was further complicated by other cancer-associated thrombophilic conditions, including deep vein thrombosis (DVT) and nonbacterial thrombotic endocarditis (NBTE). To our knowledge, this is the first reported case in the literature where PMD has been observed as an initial manifestation of lung cancer. The patient was treated with targeted therapy for lung cancer and anticoagulation for thrombotic complications. This case highlights the importance of considering underlying malignancies in patients presenting with unusual thrombotic events, even in anatomical locations not typically associated with cancer-related thrombosis. It also underscores the diverse and sometimes unexpected manifestations of cancer-associated thrombosis, challenging clinicians to maintain a high index of suspicion for underlying malignancies in patients presenting with atypical thrombotic events.