Signet Ring Cell Carcinoma of Unknown Primary Complicated with Pulmonary Tumor Thrombotic Microangiopathy and Krukenberg Tumor

Pulmonary tumor thrombotic microangiopathy (PTTM) is a rare disease that shows hypoxia with severe pulmonary hypertension related to malignant tumor. Diagnosis is difficult due to rapid clinical progression and the need to demonstrate pathological findings from lung biopsy. A 64-year-old woman visited our hospital with hypoxia and pulmonary hypertension. Diffuse granular shadows in the centrilobular area and ground-glass shadows in both lungs and left ovarian tumor were found on radiological imaging. PTTM was suspected, but pulmonary artery blood aspiration by right cardiac catheter failed to detect cancer cells. We could not obtain lung or ovary biopsies because of hypoxia or pulmonary hypertension. The patient died due to respiratory failure. Signet ring cell carcinoma of unknown primary, PTTM, and Krukenberg tumor were diagnosed on autopsy. Since early diagnosis facilitates adequate treatment, physicians should not miss the opportunity for biopsy in cases of suspected PTTM.