title: Low-Fat Plexiform Spindle Cell Lipoma With Prominent Myxoid Stroma: An Unusual Oral Presentation and Immunohistochemical Analysis.
abstract: Spindle cell lipoma (SCL) and pleomorphic lipoma constitute a spectrum of lipomatous lesions with distinctive clinicopathological features. Multiple variants of SCL have been reported including fibrous, plexiform, vascular, pseudoangiomatous, low-fat/fat-free, and myxoid changes. This paper describes an unusual patient with a 1-cm submucosal nodular lesion excised from the buccal mucosa of a 55-year-old woman with classic histopathological and immunohistochemical features of "low-fat" plexiform SCL with prominent myxoid stroma, which initially suggested a soft-tissue myxomatous lesion other than SCL. The current lesion exhibited microscopically few adipocytes supported by network-like myxoid proliferations with retraction artifacts from the surrounding stromal connective tissue. Immunohistochemistry was positive for vimentin, CD34, CD10, and S100, the latter only on adipocytes. The Ki-67 was <1%. Pan-cytokeratin (AE1/AE3), desmin, alpha-SMA, EMA, bcl-2, p53, and remarkably retinoblastoma protein (pRb) were negative. "Low-fat" plexiform SCL bear no significant prognostic significance, but this lesion may challenge the diagnosis even experienced pathologists.
authors.affiliation: *Department of Pathology and Forensic Medicine, Ribeirão Preto Medical School (FMRP/USP), University of São Paulo (USP), Ribeirão Preto †Public Health Service, Jaboticabal ‡Hematology Division, Department of Clinical Medicine, Ribeirão Preto Medical School (FMRP/USP), University of São Paulo (USP), Ribeirão Preto §Oral Pathology, Department of Stomatology, Public Oral Health, and Forensic Dentistry, University of São Paulo, School of Dentistry of Ribeirão Preto (FORP/USP), University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Jessica Luana
authors.initials: JL
authors.lastname: Dos Santos
authors.forename: Eduardo Akira
authors.initials: EA
authors.lastname: Ocamoto
authors.forename: Luciana Yamamoto
authors.initials: LY
authors.lastname: Almeida
authors.forename: Lucas Ribeiro
authors.initials: LR
authors.lastname: Teixeira
authors.forename: Alfredo
authors.initials: A
authors.lastname: Ribeiro-Silva
authors.forename: Jorge Esquiche
authors.initials: JE
authors.lastname: León
mesh_terms: D017667:Adipocytes / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008067:Lipoma / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology*; D008875:Middle Aged; D009061:Mouth Mucosa / Q000473:pathology / Q000601:surgery; D009062:Mouth Neoplasms / Q000378:metabolism* / Q000473:pathology* / Q000601:surgery