Microscopic Description -- Temporal Bone Mass


Histologic sections revealed soft tissue with an abundance of foamy macrophages, multinucleated giant cells adjacent to cholesterol clefts, fibrous tissue, and neovascularization (Figs. 4, 5). Some of the macrophages contained hemosiderin and there was focal perivascular chronic inflammation consisting of lymphocytes and plasma cells. In several fragments, there were small aggregates of adipose tissue and skeletal muscle with associated macrophages and multinucleated giant cells. Numerous fragments of remodeled bone were present within the inflammatory tissue (Fig. 6). Of the many sections, one fragment contained a small cystic structure lined by squamous epithelium with hyperkeratosis (Fig. 7). Masson's trichrome stain highlighted the fibrous tissue within the mass and immunohistochemical staining with CD68 confirmed the macrophage lineage of the majority of the mononuclear and foamy cells (Fig. 8).


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