Giant Proliferating Trichilemmal Tumor of the Gluteal Region SEMSETTIN KARACA, MD, ✽ MUSTAFA KULAC, MD, ✽ FATMA HUSNIYE DILEK, MD, † COSKUN POLAT , MD, ‡ AND SEZGIN YILMAZ, MD ‡ ✽ Department of Dermatology, † Department of Pathology, and ‡ Department of General Surgery, School of Medicine, Afyon Kocatepe University, Afyon, Turkey BACKGROUND. Proliferating trichilemmal tumors are rare cuta- neous neoplasms that show features of typical pilar cysts but also show extensive epithelial proliferation, variable cytologic atypia, and mitotic activity. Proliferating trichilemmal tumors are benign lesions; however, there are numerous reports of malignant pro- liferating trichilemmal tumors. OBJECTIVE. We present a case of benign proliferating trichilemmal tumor of an 81-year-old woman that was located on the left superior gluteal region for 30 years. METHODS. A tumor measuring 9  7 cm was surgically excised with a 1 cm conservative margin of normal tissue. RESULTS. Based on the histopathologic findings of tumor, this case was diagnosed as proliferating trichilemmal tumor. The patient’s condition was successfully treated with total excision. CONCLUSIONS. Our case is an unusual presentation of proliferat- ing trichilemmal tumor. Physicians should be aware of this entity while differentiating cutaneous tumor located on the gluteal region. © 2005 by the American Society for Dermatologic Surgery, Inc. • Published by BC Decker Inc ISSN: 1076–0512 • Dermatol Surg 2005;31:1734–1736. SEMSETTIN KARACA, MD, MUSTAFA KULAC, FATMA HUSNIYE DILEK, COSKUN POLAT, AND SEZGIN YILMAZ HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS. PROLIFERATING TRICHILEMMAL tumor (PTT) is an uncommon adnexal neoplasm that usually presents as a slow-growing mass in the skin. 1,2 PTT was first reported by Wilson-Jones in 1966. 3 PTT has been reported under dif- ferent names in the literature: proliferating epidermoid cyst, invasive pilomatrixoma, trichochlamydocarcinoma, giant hair matrix tumor, and keratinizing trichilemmoma. 4 Ninety percent of PTTs occur on the scalp, but they have also been found on the forehead, nose, back, chest, abdomen, buttocks, elbow, wrist, mons pubis, and vulva. 5,6 Most patients are women (84%). The age range is 27 to 83 years. Although PTT is considered a benign lesion, it may be locally aggressive. 7 There are numerous reports of malignant PTT. 1 We present an unusual case of PTT that was located in the gluteal region of an elderly woman. Case Report An 81-year-old woman presented with a 30-year history of a slowly enlarging, ulcerated, painless mass with a puru- lent discharge with bad odor on her back. One year prior to her evaluation, she noticed a rapid increase in size. She had no history of trauma to the gluteal region and no der- matologic complaints. On the left back area, a 9  7 cm tumor with elevated margins was present (Figure 1). The tumor was resected with a 1 cm free margin of normal tis- sue. Histopathology Grossly, the excised specimen consisted of a well- demarcated subcutaneous mass that measured 5.5  5.5  4 cm and was covered by unremarkable skin that meas- ured 10  6.5 cm. The cut surface of the mass revealed a gray-tan tumor with multiloculated cystic spaces filled with stark yellow-tan fluid (Figure 2). Microscopically, the tumor was well demarcated from the surrounding tissue and showed coalescing masses of squamous epithelium with abrupt keratinization and keratin pearls (Figure 3). There were solid and cystic areas, some containing cho- lesterol clefts and blood. Foci of calcifications were pres- ent. There was minimal cellular atypia and only rare mitotic figures. Discussion PTT is a skin neoplasm that probably arises from a preex- isting trichilemmal cyst subsequent to trauma or inflam- mation; it can also occur without a preexisting cyst. 7 Usu- ally, the clinical presentation of PTT is a pink to reddish, long-standing, subcutaneous, cystic nodule that slowly progresses to a large, nodular mass that is often irregular in shape, and 90% of cases are located in the scalp. 4,7 The residual 10% of cases are located in other locations. It may ulcerate, bleed, and produce a purulent discharge. 5 In more than 80% of cases, women are affected, and the Address correspondence and reprint requests to: Semsettin Karaca, MD, Afyon Kocatepe Universitesi, Ahmet Necdet Sezer Uygulama ve Arastirma Hastanesi, Dermatoloji Klinigi (Pembe Hastane), Afyon, Turkey; or e-mail: skaraca@aku.edu.tr; shems@hotmail.com.