title: A case of 'fat-free' pleomorphic lipoma occurring in the upper back and axilla simultaneously.
abstract: Pleomorphic lipoma is a rare neoplasm that predominantly occurs in the dermis or subcutis of the posterior neck, upper back, and shoulders. Although pleomorphic lipoma is a benign tumor, it may contain atypical cells. As a variant of spindle cell lipoma, pleomorphic lipoma clinically presents as a slow-growing and well-circumscribed subcutaneous mass. Rarely, some patients have multiple lesions. Histologically, pleomorphic lipoma is composed of mature fat, bland spindle-shaped mesenchymal cells, and coarse 'rope-like' collagen bands. In addition, lipoma contains multinucleated floret-like giant cells. Although spindle cell lipoma/pleomorphic lipoma with little fat was seen in the original series described by Enzinger and Harvey, cases with little to no fat remain diagnostically challenging. Herein, we report a case of 'fat-free' pleomorphic lipoma occurring in the upper back and axilla simultaneously. Although the lipoma was typically composed of bland spindle-shaped cells, rope-like collagen, scattered floret-like giant cells, and striking stromal myxoid change in the background, mature fat was absent. Immunohistochemical analyses showed positive staining for CD34, vimentin, and Bcl-2, and negative staining for S100, confirming the diagnosis of pleomorphic lipoma.
authors.affiliation: Department of Pathology, the First Affiliated Hospital and College of Basic Medical Sciences, China Medical University, North 2nd Road, 92#, Shenyang 110001, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Di
authors.initials: D
authors.lastname: Zhang
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Na
authors.initials: N
authors.lastname: Tang
authors.forename: En-Hua
authors.initials: EH
authors.lastname: Wang
mesh_terms: D000273:Adipose Tissue / Q000473:pathology*; D000368:Aged; D001365:Axilla; D001415:Back / Q000473:pathology* / Q000601:surgery; D006258:Head and Neck Neoplasms / Q000473:pathology* / Q000601:surgery; D006801:Humans; D008067:Lipoma / Q000473:pathology* / Q000601:surgery; D008297:Male; D011379:Prognosis