title: A malignant gastrointestinal stromal tumor with osteoclast-like giant cells.
abstract: Gastrointestinal stromal tumors (GISTs) are a heterogeneous group of mesenchymal tumors with a wide spectrum of histologic features and consistent expression of c-Kit. We describe an 85-year-old woman who presented with left lower quadrant abdominal pain and was subsequently diagnosed as having a malignant GIST. The tumor was composed of short fascicles of spindle cells. In addition to the presence of tumor giant cells, the tumor also demonstrated many osteoclast-like giant cells, a feature that has not been previously described in the literature. These giant cells expressed histiocytic markers CD68 and alpha(1)-antitrypsin but not c-Kit, a marker for GISTs. Electron microscopy showed no features of smooth muscle differentiation in the giant cells. The possible origin of the osteoclast-like giant cells is discussed in the context of immunohistochemical and ultrastructural characteristics.
authors.affiliation: Department of Pathology, Princess Margaret Hospital, Kowloon, Hong Kong.
authors.forename: Kai Man
authors.initials: KM
authors.lastname: Leung
authors.forename: Shun
authors.initials: S
authors.lastname: Wong
authors.forename: Tat Chong
authors.initials: TC
authors.lastname: Chow
authors.forename: Kam Cheong
authors.initials: KC
authors.lastname: Lee
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000473:pathology*; D006801:Humans; D010010:Osteoclasts / Q000473:pathology*