Pulmonary Tumor Thrombotic Microangiopathy (PTTM) is a rare condition associated with neoplastic disorders, predominantly gastric cancer, leading to pre-capillary Pulmonary Hypertension (PH). The pathologic mechanism involved is a fibrocellular intimal proliferation of small pulmonary vessels sustained by nests of carcinomatous cells lodged in pulmonary vasculature. Clinical presentation is nonspecific, including progressive dyspnea and dry cough. Diagnosis of PTTM is extremely challenging ante-mortem and prognosis is poor. Here we describe the case of a middle-aged man, without known previous cancer history. The clinical course was rapidly unfavorable, with progressive dyspnea and PH associated with hemodynamic instability, eventually culminating in patient’s death. PTTM diagnosis was made post-mortem. PTTM should be considered in any patient presenting with unexplained PH, especially if it is rapidly progressive, poorly responsive to standard approaches or there is suspected history of malignancy. A prompt diagnosis of PTTM could help in bringing light into this still under-recognized condition.