An autopsy case of Trousseau's syndrome with tumor thrombosis in unknown primary squamous cell carcinoma of the head and neck.

Trousseau's syndrome (TS) and tumor thrombosis (TT) are known as cancer-associated thrombosis with poor prognosis. TS is extremely rare in patients with squamous cell carcinoma. In this study, we report an unknown primary squamous cell carcinoma of the head and neck (SCCHN) patient with TS and TT in pulmonary artery definitely diagnosed by autopsy. A 73-year-old man had a past surgical history for unknown primary SCCHN and lung metastases. Three years after the initial surgery, the patient had multiple cerebral infarction, deep venous thrombosis in the legs and mediastinum metastases. Our diagnosis was TS and treatment with chemotherapy and unfractionated molecular heparin started. It could help control the hypercoagulative state and cancer progression, but finally, he died from progressive disease (mediastinum metastases and pulmonary embolism) five years after the initial surgery. An autopsy revealed multiple metastases and thrombosis in the pulmonary artery with squamous cell carcinoma microscopically. Although there is no established treatment for managing TS, intensive therapy such as a combination of chemotherapy and anticoagulant therapy can be effective in improving hypercoagulation therapy. In addition, an autopsy should be considered for patients with thrombosis to distinguish between TS and TT. © The Japan Society of Clinical Oncology 2020.