Multiple pilomatrixomas: case report and literature review.

Abstract

Pilomatrixoma is a rare, benign, circumscribed, calcifying epithelial neoplasm that is derived from hair matrix cells. Multiple pilomatrixomas are uncommon. We describe a case of multiple pilomatrixomas in a 23-year-old black woman who presented with lesions on her face and back. Based on the results of the clinical examination, she was provisionally diagnosed with either calcified sebaceous cysts or calcified lymph nodes. She underwent surgical excision of the masses. On histopathology, the lesions were identified as pilomatrixomas. We attribute our original failure to diagnose this condition to our lack of familiarity with it. We discuss the presentation, differential diagnosis, and other characteristics of pilomatrixomas.

Introduction

Pilomatrixoma, also known as pilomatricoma and calcifying epithelioma of Malherbe, is a rare, benign tumor that originates in the cells of the hair follicle matrix. It presents as a slowly growing, subcutaneous, firm to hard, superficial, mobile nodule. It often arises on the head and neck and less often on the trunk and extremities. Multiple pilomatrixomas are uncommon.

The tumor was first described in 1880 by Malherbe and Chenantais, who believed that it arose from the sebaceous glands. (1) The term pilomatrixoma was coined by Forbis and Helwig in 1961 to make it clear that the cells of origin are the outer root sheath cells of the hair follicle. (2)

Pilomatrixoma often eludes clinical diagnosis because non-dermatologists are generally not very familiar with it. We describe a case of multiple pilomatrixoma that was not diagnosed until postexcisional histopathology was performed.

Case report

A 23-year-old blackwoman was referred to the otolaryngology clinic at the University of Texas Medical Branch in Galveston with a 4-year history of slowly growing, bilateral masses over the parotid area. The mass on the right side had been intermittently painful. At about the same time the facial lesions appeared, she had also noticed a swelling on her back.

On physical examination, the masses were found to be hard, lobulated, and freely mobile over the deeper structures. The mass in the right parotid area was approximately 3 cm in diameter (figure 1, A), and the diameter of the mass on the left was approximately 2 cm. On her back was a 3-cm tumor that was contained in a sac-like skin appendage (figure 1, B).

Computed tomography (CT) demonstrated the presence of calcified masses overlying both parotid glands; no glandular involvement was evident (figure 2). The patient exhibited no signs of myotonia or systemic bony abnormalities. A provisional diagnosis of calcified sebaceous cysts or calcified lymph nodes was made.

Excision of the masses was performed with conscious sedation and local anesthesia. The excised lesions consisted of well-circumscribed and encapsulated nodules. They ranged in size from 3.0 x 3.0 x 1.0 to 3.5 x 2.5 x 2.0 cm, and they contained light-yellow, chalky, gritty material.

On light microscopy, the specimens had a pleomorphic appearance with variable cellularity and an admixture of dark-staining cellular and light-staining paucicellular areas (figure 3). The more cellular areas consisted of dark-staining, basophilic small cells arranged as irregularly shaped islands within less cellular and more eosinophilic centers that consisted of ghost (shadow) cells. Both abrupt and gradual transitions of the basaloid cells to squamous and ghost cells were seen, along with areas of dystrophic calcification. The ghost cells contained abundant eosinophilic cytoplasm with and without small hyperchromatic nuclei. Other cellular components included histiocytes, occasional multinucleated giant cells, and areas of calcification. Based on the results of the histopathologic analysis, we were able to make a diagnosis of multiple pilomatrixomas.

[FIGURE 1 OMITTED]

The patient's postoperative course was uneventful, and she was lost to follow-up after the sutures were removed.

Discussion

In the 1970s, Moehlenbeck reviewed 140,000 skin tumors and found that pilomatrixomas accounted for only 0.12% of them. (3) Some 40 to 77% of pilomatrixomas occur on the head and neck; of these, lesions of the neck are the most common, followed by lesions of the cheeks, scalp, and periorbital areas. (4-9) Pilomatrixomas are not known to occur on the palms, soles, or genitalia? Approximately 60% of pilomatrixomas occur in patients younger than 20 years; the distribution is somewhat bimodal, as a smaller peak is seen in the elderly. (3,4,8)

[FIGURE 2 OMITTED]

The ratio of female to male patients ranges from 0.43:1 to 2.45:1; most authors have reported a female preponderance. (4-10) One study that did not find a female preponderance (0.97:1) was conducted by Lan et al in Taiwan; they theorized that their atypical finding might have reflected the racial characteristics of their study population. (9) Geh and Moss have reported a familial association. (11)

A pilomatrixoma presents as a solitary cystic swelling that is typically painless and therefore often ignored. (The pain reported by our patient was atypical.) It eventually progresses to become a calcified lesion. Malignant transformation is rare, as fewer than 20 cases have been reported in the literature. (5,6,8,12) Malignant transformation must be suspected in a patient who experiences several local recurrences. (13) Greene et al described a pilomatrixoma that mimicked an ulcerated squamous cell carcinoma. (14)

[FIGURE 3 OMITTED]

Multiple pilomatrixomas are uncommon, as most authors report an incidence in the range of 2 to 10%. (15,16) However, in their review of 179 cases, Lan et al found only 1 case of multiple lesions (0.56%). (9) Multiple and familial lesions have occurred in association with myotonic dystrophy, Gardner syndrome, Turner syndrome, Steinert disease, and sarcoidosis. (4,5,7-9,11,13,15) Our patient did not have a family history of pilomatrixoma, nor did she demonstrate any of the features of these associated syndromes.

In view of the rarity of pilomatrixomas, a high index of suspicion is required if the diagnosis is to be made on the basis of the clinical examination. While dermatologists tend to be aware of this condition, most otolaryngologists are not, which is somewhat surprising because pilomatrixomas are among the most commonly excised superficial masses in children. (17) In the large series by Lan et al, the correct preoperative clinical diagnosis was made in only 2 of the 179 cases (1.1%). (9) Pilomatrixomas are often initially misdiagnosed as sebaceous or dermoid cysts. The differential diagnosis includes ossifying hematoma, branchial cyst, adenopathy, preauricular cyst, giant-cell tumor, chondroma, fibroxanthoma, foreignbody reaction, and osteoma cutis. (4-7,9,10,13) When a lesion is found over the preauricular area, a tumor of the parotid gland must be ruled out.

It is difficult to make the diagnosis on fine-needle aspiration biopsy alone. (18) In our case, the diagnosis was made by two surgical pathologists (S.A.G. and P.A.). Imaging modalities are of limited help, but the presence of a sharply demarcated, calcified, subcutaneous nodule on CT should raise suspicion. Magnetic resonance imaging (MRI) is not diagnostic, but pilomatrixomas have appeared as high-intensity signal bands on T2-weighted MRI. (19)

Histopathologic examination will reveal a sharply demarcated dermal nodule that extends into subcutaneous fat. At the periphery are nucleated basaloid cells, and at the center are non-nucleated ghost cells. The basaloid cells generally have small, uniform nuclei, scant cytoplasm, and indistinct cell borders surrounded by fibrillary material. Sheets of ghost cells, which evolve from basaloid cells, represent dead cells that have retained their shape. A transitional area may be noted between the basaloid area and the ghost cells; such an area contains apoptotic cells. Calcification is predominantly seen in the area of the ghost cells. Giant cells, which represent a foreign-body reaction to the ghost cells, are also seen in the area where keratin is abundant.

Wide local excision with primary closure of the defect is usually curative. (14)

References

(1.) Malherbe A, Chenantais J. Note sur l'epithelioma calcifie des glandes sebacees. Prog Med 1880;8:826-37.

(2.) Forbis R Jr., Helwig EB. Pilomatrixoma (calcifying epithelioma). Arch Dermatol 1961;83:606-18.

(3.) Moehlenbeck FW. Pilomatrixoma (calcifying epithelioma). A statistical study. Arch Dermatol 1973;108(4):532-4.

(4.) Yencha MW. Head and neck pilomatricoma in the pediatric age group: A retrospective study and literature review. Int J Pediatr Otorhinolaryngol 2001;57(2):123-8.

(5.) Danielson-Cohen A, Lin SJ, Hughes CA, et al. Head and neck pilomatrixoma in children. Arch Otolaryngol Head Neck Surg 2001; 127(12):1481-3.

(6.) Duflo S, Nicollas R, Roman S, et al. Pilomatrixoma of the head and neck in children: A study of 38 cases and a review of the literature. Arch Otolaryngol Head Neck Surg 1998;124(11):1239-42.

(7.) Agarwal RP, Handler SD, Matthews MR, Carpentieri D. Pilomatrixoma of the head and neck in children. Otolaryngol Head Neck Surg 2001;125(5):510-15.

(8.) Julian CG, Bowers PW. A clinical review of 209 pilomatricomas. J Am Acad Dermatol 1998;39(2 Pt 1):191-5.

(9.) Lan MY, Lan MC, Ho CY, et al. Pilomatricoma of the head and neck: A retrospective review of 179 cases. Arch Otolaryngol Head Neck Surg 2003;129(12):1327-30.

(10.) Thomas RW, Perkins JA, Ruegemer JL, Munaretto JA. Surgical excision of pilomatrixoma of the head and neck: A retrospective review of 26 cases. Ear Nose Throat J 1999;78(8):541,544-6, 548.

(11.) Geh JL, Moss AL. Multiplepilomatrixomata and myotonic dystrophy: A familial association. Br J Plast Surg 1999;52(2):143-5.

(12.) Dutta R, Boadle R, Ng T. Pilomatrix carcinoma: Case report and review of literature. Pathology 2001;33(2):248-51.

(13.) Goufman DB, Murrell GL, Watkins DV. Pathology forum. Quiz case 2. Pilomatricoma (calcifying epithelioma of Malherbe). Arch Otolaryngol Head Neck Surg 2001;127(2):218, 220.

(14.) Greene RM, McGuff HS, Miller FR. Pilomatrixoma of the face: A benign skin appendage mimicking squamous cell carcinoma. Otolaryngol Head Neck Surg 2004;130(4):483-5.

(15.) Geh JL, Wilson GR. Unusual multiple pilomatrixomata: Case report and review of the literature. Br J Plast Surg 1999;52(4):320-1.

(16.) Wygledowska-Kania M, Kamifiska-Winciorek G, Krauze E, et al. Multifocal type of pilomatrixoma. Adv Med Sci 2007;52:251-3.

(17.) Knight PJ, Reiner CB. Superficial lumps in children: What, when, and why? Pediatrics 1983;72(2):147-53.

(18.) Viero RM, Tani E, Skoog L. Fine needle aspiration (FNA) cytology of pilomatrixoma: Report of 14 cases and review of the literature. Cytopathology 1999;10(4):263-9.

(19.) Hoffmann V, Roeren T, Moller P, Heuschen G. MR imaging of a pilomatrixoma. Pediatr Radiol 1998;28(4):272.

Shashidhar Sadda Reddy, MD, MPH; Swarupa A. Gadre, MD; Patrick Adegboyega, MD; Arun K. Gadre, MD

From the Department of Otolaryngology--Head and Neck Surgery (Dr. Reddy and Dr. A.K. Gadre) and the Department of Pathology (Dr. S.A. Gadre and Dr. Adegboyega), University of Texas Medical Branch, Galveston.

Corresponding author: Arun K. Gadre, MD, Department of Surgery, University of Louisville, 601 S. Floyd St., Suite 700, Louisville, KY 40202. Phone: [phone]; fax: [phone]; e-mail: [e-mail]