Earlobe Pilomatrixoma in Children: Clinical Features and Surgical Management

Introduction

Pilomatrixoma is a type of skin tumor that develops from early hair follicle cells. Initially termed “epithelioma calcificans” or “calcifying epitheliomas of Malherbe”, it was believed by Malherbe and Chenantias in 1880 to originate from sebaceous glands [1]. These tumors are most found on the skin of the head and neck, with around 40% occurring on the head, especially in the midface, and are relatively rare in the ear, particularly the earlobe [2]. They typically appear in the first 2 decades of life, with over 60% of cases presenting during this period [3]. The incidence rate is estimated to be 1 in 1000 skin biopsies, suggesting that clinical diagnosis is infrequent [4]. Pilomatrixomas typically manifest as painless, well-defined nodules ranging from 0.5 to 4.5 cm in diameter, occasionally displaying red or blue discoloration [4]. They are frequently observed in children, with a higher occurrence in female patients. Despite being a recognized skin condition in this demographic, they are often misdiagnosed as other skin lesions [5]. Therein, this report describes a case of a 6-year-old girl who had a solitary, painless nodule on her right earlobe.

Case Report

A 6-year-old girl, medically and surgically free, presented to our pediatric otolaryngology clinic with a concern of a mass in her right earlobe. This mass was first noticed when she was 3 years old. The mass is painless and stable in size, with no aggravating or relieving factors. The patient has no history of any trauma/injury to the area, nor did she have any piercings. The patient did not experience any symptoms, and the size of the lesion remained stable, with no growth for 3 years. On physical examination, we found that the mass was firm, non-tender, well-circumscribed, and mobile, with no overlying skin changes. No prior imaging or investigations had been done. Treatment options (including observation and surgical intervention) were discussed with the parents, and they agreed to go for surgery to get rid of this lesion. Two months later, the patient was taken to the operating theater for elective surgery. The patient was draped and sterilized in the usual aseptic manner.

Using a blade size 15, a horizontal incision was made on the right earlobe posteriorly. Then, we continued dissecting the mass until we reached its base. It was then removed entirely and sent for histopathology, as shown in Figure 1, confirming the pilomatrixoma diagnosis. The excised mass was received in our laboratory, using formalin, a firm piece of lesional tissue with a maximum dimension of 0.6 cm. Microscopically, the histological sections showed a lesion composed of alternating eosinophilic and basophilic calcified foci (Figure 2). On closer examination, the eosinophilic foci demonstrated abundant anucleate eosinophilic keratinocytes (ghost cells) (Figure 3). Although no basaloid or transitional cells were identified, the microscopic findings, along with the clinical presentation and location of the lesion, were consistent with pilomatrixoma [6]. Furthermore, multinucleated giant cells were appreciated in multiple areas within the slide (Figure 4), a common finding in pilomatrixoma. The lack of basaloid and transitional cells is suggested to be related to the age of the lesion, whereby the ghost cell ratio increases as the lesion gets older and more mature [7].

Discussion

This case report highlights the importance of identifying and recognizing pilomatrixoma as a differential diagnosis for pediatric earlobe lesions, particularly considering how infrequent its presentation is in this location. As we elaborate here, we emphasize the value of clinical awareness to avoid unnecessary investigations and ensure appropriate management.

Pilomatrixoma is a relatively rare benign skin lesion of the hair follicle matrix primarily diagnosed in the pediatric population, with a propensity to affect female patients. A systematic review of 17 articles with a total 318 cohort estimated that the mean age of diagnosis is 6.7 years, mainly detected below the age of 10 years [1]. Pilomatrixoma originates in the hair follicle matrix and predominantly occurs in the head and neck region. A retrospective study published in 2024 reviewed 171 patients with pilomatrixoma in a single center in China. The study found that the head and neck area was the most commonly reported region (77.2%), followed by the upper limbs (12.9%), trunk (7.6%), and lower limbs (2.3%) [8]. This distribution excludes non-hair-bearing areas, such as the palms and soles, which highlights the condition’s predilection for areas rich in hair follicles and sebaceous glands, as the tumor’s origin is from the hair follicle matrix [9].

Interestingly, the cheek and the pre-auricular areas have been found to be the most commonly involved areas in the head and neck; however, the auricle is a rare location. One article published in 2019 mentioned that only 2 case reports had been found of pilomatrixoma in the auricle within the English literature review, and both patients were of pediatric age [10]. Another article published in 2022 reviewed the literature from 1969 to 2021 and identified only 16 case reports about pilomatrixoma in the auricle, with the earlobe being where they were mostly found, as in our case [11]. The incidence is estimated at up to 0.12% of all cutaneous neoplasms, accounting for 1 in 1000 skin biopsies [4,9]. Pilomatrixoma usually presents as a slow-growing, asymptomatic firm mobile mass typically solitary, with a blue-reddish discoloration [12]. On physical examination, pilomatrixoma is firm to palpation because it is usually up to 90% calcified, with an average size of 1.2 cm.

Two distinct signs should be sought while examining pilomatrixoma, “tent sign” and “teeter-totter” sign; the former is when the skin is stretched over the tumor calcification and forms a tent-like structure, while the latter is when applying pressure over one end leads to elevation of the contralateral end. However, these typical characteristics are not always present [13]. As for the etiology and pathogenesis, pilomatrixoma is due to a somatic mutation leading to activation of the B-catenin gene (CTNNB1), an essential signaling protein in the development of hair follicles [14]. There have been reports of familial pilomatrixoma, which are usually multiple and are associated with other conditions and syndromes such as myotonic dystrophy, Gardner syndrome, Turner syndrome, and familial adenomatous polyposis [12–14].

Because pilomatrixoma is most diagnosed in the pediatric age group, one should consider the other differential diagnoses that can imitate it, such as dermoid cyst, branchial cleft cyst, and sebaceous cyst. For this reason, ultrasonography is often used to exclude or support the diagnosis of pilomatrixoma; it is, in fact, the modality of choice for the pediatric population, due to its non-radiation nature. The ultrasonography findings supporting the diagnosis of pilomatrixoma include an ovoid complex lesion located between the dermis and subcutaneous fat, resulting in thinning of the overlying dermis [1]. However, biopsy remains the criterion standard and definitive way of diagnosing pilomatrixoma, as highlighted in our study, with discouraged use of fine needle aspiration [12]. Complete surgical excision is the management of choice, with a low recurrence rate [1,14]. One drawback to our case is that we should have scheduled any future appointments to assess for recurrence in the patient. In a systematic review published in 2016, the authors suggested an algorithm (Figure 5) for diagnosing head and neck pilomatrixoma lesions and their management [1]. In our case, the patient had classical physical findings of pilomatrixoma. Thus, she did not undergo any imaging or any prior investigations and was taken to surgery, with confirmation of the diagnosis histologically.

Conclusions

This case emphasizes the importance of considering pilomatrixoma in the differential diagnosis of pediatric head and neck masses and how it might even present in some unusual locations, such as the auricle. Recognizing its clinical features can facilitate effective management while minimizing unnecessary diagnostic tests. In this case, we highlighted an efficient approach and raised awareness of pilomatrixoma’s distinctive presentation.