The histologic spectrum, prognosis, and histogenesis of the sarcomatoid carcinoma of the pancreas.

A series of 12 cases of pancreatic carcinoma with sacroma-like transformation were studied. Four distinctive histologic types were identified: spindle cell carcinoma, malignant giant cell tumor, pleomorphic giant cell carcinoma, and round cell anaplastic carcinoma. The spindle cell carcinoma had a predominance of malignant spindle and undifferentiated cells. Hemorrhage and sarcomatoid stroma with abundant osteoclast-like giant cells were the features in the malignant giant cell tumor. The pleomorphic giant cell carcinoma was characterized by abundant malignant giant cells. The round cell anaplastic type was formed by monotonous sheaths of small, round, and plump cells with rare giant cells. The first three types are considered to be ductal in origin, whereas the fourth type is believed to arise from acinar or possibly insular tissue. The differential diagnosis includes various types of true sarcoma. Although the malignant giant cell tumor of the pancreas might have a better prognosis, the prognosis in the other three types does not differ significantly from that of the ordinary type of pancreatic carcinoma.