Pilomatrixoma and its Imitators

Abstract

Introduction: Pilomatrixomas are benign neoplasms derived from hair follicle matrix cells. They are among the most common soft tissue head and neck tumors of childhood. Pilomatrixomas are typically isolated, slow-growing, firm, nontender masses that are adherent to the epidermis but mobile in the subcutaneous plane. This clinical presentation is so characteristic that many experienced surgeons will excise suspected pilomatrixomas without prior imaging. We reviewed the results of this approach to determine whether physical examination alone differentiates pilomatrixomas from other similar soft tissue lesions of the pediatric head and neck. Methods: Computerized review of all pilomatrixomas over a 20-year period in a single academic pediatric otolaryngology practice. Results: 18 patients presented to our pediatric otolaryngology practice between 2001 and 2021 with historical and physical findings consistent with pilomatrixoma. Of the 18 patients, 7 were male and 11 were female. Ages ranged from 1.5 to 14 years, with a mean of 7.5 years. Most of the lesions (12) were located in the head and face, while the rest (6) were found in the neck. All patients were treated with complete surgical excision. Pathology confirmed pilomatrixoma in 15 patients. The remaining 3 children were found to have an epidermal inclusion cyst, a ruptured trichilemmal cyst, and a giant molluscum contagiosum lesion, respectively. One additional patient presented with a small lesion of the auricular helix that was thought to be a dermoid cyst, but proved to be a pilomatrixoma on histologic examination. Discussion: As pilomatrixomas are common and have a very characteristic presentation, surgical excision without prior diagnostic imaging will lead to correct treatment in the majority of cases. High resolution ultrasonography can help to confirm the diagnosis preoperatively, but is not definitive in large case series. Most of the cystic lesions that imitate pilomatrixoma will ultimately require surgical excision.

Keloid-like Pilomatricoma of the Auricle: A Case Report and Review of Literature

“…By contrast, pilomatricoma of the auricle was rarely reported. One retrospective study has shown that pilomatricoma of the auricle may lead to misdiagnoses because of its close clinical resemblance to other skin conditions such as a dermoid cyst compared with cases involving other body parts [ 6 ]. In addition, given the rarity of its occurrence in the auricle, clinicians may initially consider other differential diagnoses that are commonly found in this area, such as squamous cell carcinoma, or those that almost exclusively occur in the auricle, such as tumors of the ceruminous gland [ 11 ].…”

“…However, diverse clinical variants have been described, including perforating, anetodermic, proliferating, and pigmented types [ 4 , 5 ]. Consequently, pilomatricoma may mimic various skin conditions, such as epidermoid and dermoid cysts, trichilemmal cysts, and steatocystoma [ 6 ]. Diagnosis of pilomatricoma is dependent on histologic findings, which are characterized by islands of tumors in the dermal or subcutaneous layer, encompassing two types of cells, namely, basaloid matrical cells in the periphery and classic anucleated “ghost” cells toward the center, with variable areas of calcification [ 7 ].…”

What is this bump in my neck? Ultrasonographic evaluation of pediatric neck masses

“…Clinically they often present as a firm, freely movable, slow‐growing mass in the children. They are commonly seen in the head and neck and their size of generally vary between 0.5 and 3 cm 35,36 …”

“…They are commonly seen in the head and neck and their size of generally vary between 0.5 and 3 cm. 35,36 On US, they typically appear as a well-defined subcutaneous mass with strong posterior acoustic shadowing. Color Doppler may show little peripheral vascularity (Figure 11).…”

Massive Pilomatrixoma of the Scalp: A Case Report

“…The incidence is not precise, but it is reported between one and three in 1,000 dermatohistopathologic specimens examined [ 1 ]. It usually presents as a solitary firm painless subcutaneous slow-growing mass, attached to the skin with no invasion of the underlying tissue [ 1 , 2 , 5 , 8 ]. Its dimensions often range from 0.5 to 3 cm, but lesions greater than 5 cm in diameter can be seen and are described as giant pilomatrixoma [ 3 , 5 ].…”