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. 99 2 • www.entjournal.com ENT-Ear, Nose & Throat Journal · July 2009 PATHOLOG Y CLINIC 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 WHY PAY RETAIL? Our surgical microscopes are meticulously reconditioned and guaranteed for two years, at a fraction of the cost of new. We have an extensive inventory of ZEISS and lEICA Systems Guaranteed 2 yearson ~II parts and'labor:'., F OR ALL YOUR PRESCOTT'S, NC. MI[:RO§I: O P E I\IEED§ 0s/t OU'~e\ RO. Box 609 • Monument, CO 80132 VV'ebs" (800) 438-3937 (719) 481-3353 • Fax (719) 488-2268 [email protected] 0 www.surgicalmicroscopes.com Volume 88, Number 7 www.entjournal.com • 99 3.