PATHOLOGY CLINIC
Spindle-cell lipoma
Lester D.R.Thompson , MD
Figure. A:At low power, only a scant amount offat (lower right) is notedin thisspindle-celllipoma. B:Adipocytes""" are seen between bundles of spindled cells with abundant collagen. This is the typical histologic appearance of a spindle-cell lipoma. C: Foca l fat is seen at theperiphery (left), while the spindle-cell population exhibits isolated atypical ormultinuclea tedcells.Mastcellsarealso present.D: Nofatis identifiedin this tumor,but thecharacteristic spindle-cellpopulation is seen with wire- or rope-like collagenfibers.
Histolo gically, spindle-cell lipoma is a distinctive back, and sho ulders . Patients present with a painless, type of lipoma on a continuum with pleomorphic li• m obile, subcuta ne ous ma ss. In rare cases, these tumors poma. It accounts for approxim ately 1.5% of all adi• develop in other head and neck mucosal sites, such as pose tissue neopl asms. Men are affected significantly th e buccal fat pad. Spindle-cell lipomas grow as large more commonly th an women (9:1) at a mean age in the as 13 em (mea n: 3.5). Grossly, they resemble ordinary sixth decade. Th e vast majority of tumors are located lipomas, altho ugh th ey may be somew hat firmer, espe• in the subcutaneo us tissue of the posterior neck, upper cially if the spindle-cell compo nent predominates.
From the Depart ment of Patho logy, Woodland Hills Medical Center, Southern California Permanente Medical Group, Woodland Hills, Calif.
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Microscopically, these tumors are circumscribed, al• chromosom es 13q and/o r 16q- Iosses that are consid• though not truly encapsulated. They are composed of ered characteristic for this family of lipomas. mature fat cells mixed with bland spindle cells, hyper• The differential diagnosis includes liposarcoma, chromatic round cells, and multinucleated giant cells. neurofibroma, and nuchal fibroma. Complete local ex• The spindle cells are often arranged in parallel pha• cision is cur ative. lanxes admixed with wire- or rope-like collagen fibers and a myxoid stroma (figure). Mast cells are frequently Suggested reading numerous , along with occasional lymphocytes and Enzinger FM, Harvey DA. Spindle cell lipoma. Cancer 1975;36(5): 1852-9. plasma cells.Mitotic figures are inconspicuous.Myxoid Fletcher CD, Martin-Bates E. Spindle cell lipoma: A clinicopathological areas may be seen.At the opposite end of the spectrum, study with some original observations. Histopathology 1987;1l a spindle-cell tumor may feature small, spindled, and (8):803- 17. Furlong MA, Fanburg-Smith IC, Childers EL. Lipoma of the oral round hyperchromatic cells and multinucleated giant and maxillofacial region: Site and subclassification of 125 cases. cells with radially arranged (floret-like) nuclei-that Oral Surg Oral Med Oral Pathol Ora l Radiol Endod 2004;98(4): 441-50. is, the features of a pleomorphic lipoma. By definition , Mentzel T, Fletcher CD. Lipomatous tumo urs of soft tissues:An update. lipoblasts are not present. Virchows Arch 1995;427(4):353-63. On immunohistochemistry, the spindle cells express Shmookler BM, Enzinger FM. Pleomorphic lipoma: A benign tumor simulating liposarcoma. A clinicopathologic analysis of 48 cases. CD34 and they are negative for 5-100 protein.Both Cancer 1981;47(1):126-33. spindle-cell and pleomorphic lipomas exhibit losses of
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