Adenoendocrine cell carcinoma of the gallbladder clinically mimicking squamous cell carcinoma

We present the case of a 62-year-old Japanese man whose histological diagnosis was adenoendocrine cell carcinoma of the gallbladder at autopsy, but whose antemortem diagnosis was squamous cell carcinoma. The patient was admitted to hospital with complaints of occasional vomiting and abdominal pain. Abdominal computed tomography revealed a large tumor on the gallbladder involving the adjacent liver, colon, and duodenum, with multiple metastases in the greater omentum and paraportal lymph nodes. The serum level of squamous cell carcinoma antigen (SCCA) was high, whereas that of carbohydrate antigen (CA) 19-9, as well as that of carcinoembryonic antigen (CEA) was within the normal range. Due to these clinical features, we first suspected advanced squamous cell carcinoma of the gallbladder. After two cycles of gemcitabine monotherapy, the tumor had become enlarged and the regimen was changed to a combination of docetaxel and cisplatin. Though tumor regression was achieved and his serum SCCA level normalized after 3 months, the patient rejected additional chemotherapy and died 8 months after the diagnosis. The histopathological findings made by autopsy demonstrated the tumor to be an adenoendocrine cell carcinoma without squamous carcinoma cells. The case is interesting in that the clinical features were similar to those of squamous cell carcinoma of the gallbladder.