Keratin-positive giant cell-rich tumor review

Keratin-positive giant cell-rich tumor is a recently described mesenchymal neoplasm, which occurs predominantly in young women and often arises in the subcutis or bone. Histologically, tumors vary from giant cell tumor-like to xanthogranulomatous, or a mixture of both patterns. Tumors with predominantly xanthogranulomatous infiltrate and scattered mononuclear cells with bright eosinophilic cytoplasm were originally described as xanthogranulomatous epithelial tumor, a lesion which was subsequently found to be on a morphologic spectrum with keratin-positive giant cell-rich tumor. Most cases express keratin, characteristically with demonstration of dendritic-like cytoplasmic projections, and harbor HMGA2::NCOR2 fusions. High level expression of CSF1, in the absence of CSF1 gene alterations, is also frequently observed. Data on the clinical behavior of keratin-positive giant cell-rich tumor is limited. The course is often indolent, however rare cases are aggressive.