Signet-ring cell carcinoma of the gallbladder complicated by pulmonary tumor thrombotic microangiopathy.

Biliary drainage was performed in a 71-year-old man with obstructive jaundice of unknown origin; however, he died due to acute pulmonary failure. At autopsy, proliferation of adenocarcinoma cells was observed in the gallbladder mucosa transitioning from isolated signet-ring cell carcinoma (SRCC) to the subserosa and bile ducts without growth toward the gallbladder lumen. Furthermore, fibrocellular intimal proliferation, tumor emboli and organized thrombi were observed in the small pulmonary arteries. The final diagnosis was gallbladder carcinoma complicated by SRCC associated pulmonary tumor thrombotic microangiopathy (PTTM). PTTM may present as rapidly progressive dyspnea, and a high level of clinical suspicion is required to make the differential diagnosis.