Ovarian strumal carcinoid containing appendiceal-type mucinous tumor patterns presenting as pseudomyxoma peritonei.

Abstract We report for the first time a case of ovarian strumal carcinoid containing both trabecular carcinoid and mucinous glands lined by both goblet and neuroendocrine cells and a low-grade mucinous neoplasm that presented clinically as pseudomyxoma peritonei in the absence of appendiceal lesion in a 58-yr-old woman. Histologically, there were both a tall columnar cell epithelial component lacking neuroendocrine cells, showing the scalloped contours and subepithelial clefts of low-grade appendiceal-type neoplasms and a mixed goblet cell neuroendocrine element. Characteristically, both reproduced appendiceal neoplastic phenotypes in a teratoid fashion. In addition, we present previously unreported oncocytic and mucinous changes in the thyroideal components of strumal carcinoid. This case represents a rare instance of pseudomyxoma peritonei of primary ovarian origin and is an example of multiple somatic teratoid endodermal differentiations of the different sections of the embryonal gut: foregut represented by thyroid, midgut by both mucinous appendiceal components, and hindgut by trabecular carcinoid.