Carcinoid Tumor of the Cecum with Expression of p53 Gene Product

Abstract

It has recently been emphasized that endocrine cell tumors arising in the digestive tract should be classified into classical carcinoid of low grade malignancy and endocrine cell carcinoma (ECC) of high grade malignancy. Although the differential diagnosis is based on histological atypia, it is often difficult. Many ECCs have been reported to arise in the duodenum, lower colon and biliary duct. A rare case of ECC arising in the cecum is reported. A 70-year-old woman was admitted to the hospital complaining of abdominal discomfort. She had an appendectomy when young. Barium enema revealed an apple core sign up to 3cm at the cecum, and CT scan showed multiple metastatic lesions in the liver. We performed a right hemicolectomy to release the ileus. Histological study showed endocrine cell carcinoma, a mixed type combining oat cell carcinoma resembling small cell carcinoma of the lung with squamous cell carcinoma and adenocarcinoma. Most tumor cell showed strong positivity for p53 protein, wheares 7 classical carcinoid tumors studied showed no positivity. p53 protein stain is sugested to be useful in the differential diagnosis of ECC and classical carcinoid.