Distinguishing a Rare Variant of Lipidized Dermatofibroma from Nonlipidized Dermatofibromas in a Patient with Hypothyroidism and Alopecia Areata

Introduction. Lipidized dermatofibromas represent rare and often underrecognized variants of dermatofibromas. Histologically, dermatofibromas are composed of fibroblast-like spindle cells, foam cells, giant cells, siderophages, lymphocytes, capillaries, collagen fibers, and hyaline dermal collagen fibers. Lipidized dermatofibromas are characterized by numerous foam cells, Touton giant cells, and hyalinized wiry collagen in the stroma. Case report. We present a case of a 31-year-old woman with a history of hypothyroidism and alopecia areata, presenting with an enlarging 8 mm, firm erythematous nodule on her upper-mid back. Biopsy examination showed a cellular proliferation of spindle cells with peripheral collagen trapping and cholesterol clefts with associated foam cells and sclerosis, staining weakly positive for Factor XIIIa and negative for CD34. The diagnosis of a benign lipidized dermatofibroma was rendered. Conclusion. Lipidized dermatofibromas are rare histologic variants of dermatofibromas, biologically indolent, and should be distinguished from other cutaneous foamy histiocytic lesions, particularly xanthomas, which may alter patient management.