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giant cell collagenoma

Thursday 17 March 2016

Giant Cell Collagenoma is a benign dermal tumor with distinctive multinucleate cells.

The tumors appear as solitary slow-growing flesh-colored nodules arising in young and middle-aged adults.

They are located on the trunk, the upper extremities, and the face, and did not recur after complete excision. Clinically, they are diagnosed as dermal nevus, Spitz’s nevus, fibroma, or neurofibroma.

Histology reveals polypoid flat-dome-shaped lesions with a sharply demarcated matrix consisting of coarse hyalinized collagen bundles arranged in a prominent storiform pattern and separated by mucin-containing clefts.

Despite a low overall cellularity, the tumors contain numerous, occasionally bizarre-shaped, multinucleate giant cells with crowded vesicular nuclei and a pale staining foamy cytoplasm, as well as plump fibroblastlike cells with analogous nuclear morphology. Atypical nuclei or mitotic figures are not observed.

The cells are strongly positive for vimentin but negative for cytokeratin, smooth muscle actin, desmin, S-100 protein, CD34, factor XIIIa, and the macrophage markers KP1, Mac 387, and Ki-M1p, suggesting a fibroblastic origin.

These tumors probably represent a distinctive variant of solitary circumscribed storiform collagenoma (sclerotic fibroma) and propose the designation of giant cell collagenoma.