Neuroendocrine Carcinoma of the Gallbladder Arising as Double Tumor

ABSTRACT

Pleomorphic (undifferentated) carcinoma is a rare histologic type of carcinomas of the gallbladder and an atypical carcinoid is thought to be an intermediated type between carcinoid tumor and small cell carcinoma. Dense core "neurosecretory" granules can be found in the above mentioned tumors. We experienced a case of a double tumor of the gallbladder in a 51-year old male patient. Grossly, a large solid mass, about 5.0 cm in diameter, was found in the fundic portion and the neck portion also had a small 1.5 cm-sized polypoid mass. Microscopically, these lesions had features of pleomorphic carcinoma and atypical carcinoid, respectively. Immunohistochemically, they manifested reactivity for neuron specific enolase. Ultrastructural study revealed neurosecretory granules in the cytoplasms of tumor cells of the fundic and neck masses. Although light microscopic features of these tumor masses are quite different, we consider that these tumors represent a spectrum of neuroendocrine differentiation.