Pilomatricoma as a diagnostic pitfall in clinical practice: report of two cases and review of literature

Pilomatricoma in the infraorbital region

Key Clinical Message

Pilomatricoma, a rare benign skin tumor arising from hair follicle matrix cells, warrants consideration in the evaluation of subcutaneous nodules or masses, especially when presenting as painless and firm lesions. Accurate diagnosis hinges on histopathological examination, underscoring the significance of clinician vigilance and prompt intervention.

Abstract

Pilomatricoma, also referred to as Pilomatrixomas or Calcifying epithelioma of Malherbe, is a rare benign skin tumor derived from hair follicle matrix cells, presents a diagnostic challenge due to its diverse clinical manifestations. Females are more commonly affected by Pilomatricoma. This condition typically manifests as a painless, firm, and slowly progressive lesion. Histopathological analysis shows characteristic findings, such as basaloid cells at the periphery and shadow cells centrally. Immunohistochemical studies assess the expression of cytokeratin's associated with hair matrix differentiation. Complete surgical excision remains the cornerstone of treatment, ensuring favorable outcomes and minimizing the risk of recurrence. Awareness of this entity among clinicians is essential for timely recognition and appropriate intervention. In this specific case-study, we present a case of Pilomatricoma situated in the lower left orbital region of a 32-year-old male individual who had been noticing swelling in that vicinity over the preceding 7 months.

Adnexal neoplasms of the eye

Adnexal neoplasms of the eyelid encompass a wide variety of benign and malignant tumors of sebaceous, follicular, and sweat gland origin. Due to the specialized structures of the eyelid, these neoplasms present differently when compared with those of other locations. Although most dermatologists and ophthalmologists are familiar with the commonly reported adnexal tumors of the eyelid, such as hidrocystoma, pilomatrixoma, and sebaceous carcinoma, many other adnexal neoplasms have been reported at this unique anatomic site. Accurate and timely identification of these neoplasms is essential, as alterations of eyelid anatomy and function can have a negative impact on eye health, vision, and quality of life. We review the clinical and histopathologic features of common and rare eyelid adnexal neoplasms and discuss proposed treatment options.

Pilomatrixoma and its Imitators

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.

A Large Mass Displaying a Malignant Character on the Forearm: A Rare Case of Upper Extremity Pilomatrixoma

In this study, a 50-year-old male patient had a painless swelling on his right forearm. The lump on the forearm started one year ago and increased in size in the last two months. The mass was 3x6 cm and had a malignant appearance on radiological imaging. The case was reported as pilomatrixoma in the histopathological examination after marginal excision. In this case report, we emphasized that pilomatrixoma is one of the diagnoses we considered in mass formations that can be seen in the upper extremity, although rare. The large mass displaying a malignant character in radiological imaging can be pilomatrixoma, and the Tru-cut biopsy before the final surgery may help diagnosis by preventing the surgeons from aggressive surgical treatment. The marginal excision shall be enough in the definitive treatment. With this study, we aimed to discuss the place of pilomatrixoma in the orthopedic literature, which is published chiefly by otolaryngology, pathology, and dermatology clinics and lacks in the orthopedic literature because it rarely involves the extremities.

Auricle Pilomatricoma in Ear Lobule: A Case Report

Introduction

Skin tumors are prevalent in the head and neck especially auricle but pilomatricoma is extremely rare in ear lobule.

Case Report

A 7-year-old girl without a history of previous illness presented with a 1.5-month history of a lesion in the right ear lobule that tended to grow in size. It was a 2*2*2cm round, slightly painful lesion with soft tissue and light red in color that yielded bloody or serous fluid on aspiration. The lesion was enucleated. The diagnosis was pilomatricoma.

Conclusion

Although very rare, pilomatricoma should be considered as a differential diagnosis of ear lobule neoplasms.

Cytomorphological spectrum of pilomatricoma - A series of 28 cases

BACKGROUND

Pilomatricoma is a benign tumour that originates in the outer sheath of the hair follicle root. The clinical diagnosis of this rare entity is often missed, possibly due to a lack of awareness. Its characteristic cytomorphological features are sheets of ghost cells, basaloid cells, calcification and foreign body giant cell reaction. However, the above features may not all be present in all cases, rendering cytological diagnosis difficult.

MATERIALS AND METHODS

This retrospective study included all cases of pilomatricoma diagnosed on fine needle aspiration over a period of 4 years. The histopathological diagnosis was retrieved for the cases wherever possible. A detailed histopathological and cytological evaluation was performed for the various components-basaloid cells, ghost cells, calcified debris, foreign body giant cells, bare nuclei, neutrophils, and macrophages-and they were graded on a scale of 0 to 3+.

RESULTS

The 28 cases included 8 female and 20 male patients with a mean age of 34.6 years. Most cases (22 cases; 78.6%) were located in the head and neck, with the scalp being the most common site. Twenty-five cases were cytologically diagnosed as pilomatricoma based on a variable admixture of the various components-nests of basaloid cells, ghost cells, foreign body giant cell reaction, calcified debris and viable squamous cells. However, in two cases which showed an absence of basaloid cells, a differential diagnosis of epidermal inclusion cyst was also included. Another case showed a predominance of basaloid cells with a paucity of ghost cells, so a differential diagnosis of adnexal tumour was also included. Among all the cytological parameters, sheets of ghost cells followed by nests of basaloid cells and foreign body giant cell reaction had the highest sensitivity in the cytological diagnosis of pilomatricoma.

CONCLUSION

The presence of sheets of ghost cells is the most sensitive parameter for the cytological diagnosis of pilomatricoma. It is important that pilomatricoma should be considered in the differential diagnosis of subcutaneous masses, particularly in the head and neck region.

Periocular pilomatrixoma in childhood: Clinical feature and differential diagnosis

PURPOSE

To explore the clinical characteristics, imaging features, and differential diagnosis of periocular pilomatrixoma in children and provide evidence for clinical diagnosis and treatment.

METHODS

Retrospective analysis of the clinical characteristics, preliminary diagnosis, imaging features, treatment, and follow-up of the cases of pediatric periocular pilomatrixoma treated at our hospital.

RESULTS

A total of 59 patients from 4 months to 13 years of age (median age 4 years) were collected; 18 cases (30.51%) were misdiagnosed as other diseases in preliminary diagnoses. Seven cases underwent computed tomography (CT) examination, with CT value ranging from 63.4 Hounsfield Units (HU) to 952.0 HU (median value 151.0 HU). Six cases underwent magnetic resonance imaging (MRI) examination; two patients underwent an enhanced scan. The results showed that the rim of the lesion was enhanced, but the contents were not enhanced. All patients underwent surgical treatment. No recurrence was found from 1 month to 5 years of follow-up.

CONCLUSIONS

Periocular pilomatrixoma is a relatively common tumor in children, which can easily be misdiagnosed clinically as other diseases, such as sebaceous and dermoid cysts. Although not generally recommended, CT can be of significant value in the diagnosis of pilomatrixoma. MRI is of little value in the diagnosis of this disease. If CT images show high or density, the possibility of pilomatrixoma should be considered.

Benign Pilomatricoma With Osseous Metaplasia: A Rare Case

Pilomatricomas are frequently misdiagnosed benign neoplasms of the skin derived from hair matrix cells. Pilomatricomas may undergo calcification and ossification although the latter is rare and poorly documented, with only eight cases reported since 2006. We present a case of pilomatricoma with osseous metaplasia arising from the scalp in an 87-year-old female patient. She was referred by her general practitioner via the two-week cancer referral pathway, for a suspicious lesion. On examination, there was a 2 x 1cm nodule, with protruding hardened yellow material, on the right side of the patient’s occipital scalp. The lump was hard, non-tender and had been present for 17 years. The surrounding area was bleeding and slightly ulcerated. A clinical diagnosis of a ruptured epidermal cyst was made, and the patient was prepared for excision under local anaesthesia. The excised lesion of 23 x 18 x 10mm with 22 x 9mm of skin was sent for histology. This revealed a partially ulcerated dermal lesion composed of islands of keratin with ‘ghost cell’ outlines. Foreign body granulomas, transition to mature lamellar bone, and foci of calcification were noted. There were no definite populations of basaloid cells and features of malignancy were not seen. These findings are consistent with benign pilomatricoma with osseous metaplasia. The patient was discharged 4 weeks later with satisfactory wound healing. Differentiating this tumour from other commonly encountered benign masses remains a challenge, as seen in this case which was initially misdiagnosed as a ruptured epidermal cyst.

Pilomatrixoma in a child mimicking a ruptured epidermal cyst clinically and histopathologically: Case report

Introduction and importance

Pilomatrixoma is a superficial benign skin tumor that originates from the matrix cells of the hair follicles. It presents more frequently during the first two decades of life and usually involves the head and neck, most often in the eyelid or eyebrow area.

Case presentation

We present a case of pilomatrixoma, which appeared at the age of 14 years with history of recurrent inflammation and discharge mimicking a ruptured epidermal cyst.

Discussion

Pilomatrixomas are often confused clinically with other benign masses, encountered in the clinical practice more frequently like dermoid cysts and epidermal inclusion cysts. The rate of accurate preoperative diagnosis ranges between 0%–30% and the correct diagnosis can be established only after excision and histopathological examination. Our case demonstrates an atypical presentation of pilomatrixoma as an epidermal inclusion cyst.

Conclusion

Ophthalmologists and ocular pathologists should be aware of the atypical presentation of pilomatrixomas to ensure early accurate diagnosis and curative treatment.

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Pilomatrixoma is a benign skin tumor with typical histopathological appearance.

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Pilomatrixoma is often confused clinically with an epidermal cyst.

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Accurate diagnosis and complete excision of pilomatrixoma is essential.

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Our case demonstrates the pitfall in diagnosing pilomatrixoma.

Optimal Timing of Surgical Excision in Pediatric Pilomatricoma: Association between Clinicopathological Features and Cosmetic Outcomes

Background

The treatment of choice for pilomatricomas is surgical excision; however, data for the optimal timing of treatment and cosmetic outcomes are limited.

Objective

This study aimed to investigate the optimal timing of treatment in pilomatricomas by considering clinicopathological findings and cosmetic outcomes.

Methods

Seventy-three pilomatricomas patients aged ≤15 years were retrospectively reviewed. Patients were classified into early excision (disease duration ≤12 months, group A) and delayed excision groups (disease duration >12 months, group B). Tumor characteristics, and histopathological features with evolutionary stages were assessed. Cosmetic outcomes were evaluated by the Modified Vancouver Scar Scale (MVSS), 5-point patient satisfaction score, and complication rates.

Results

Group A showed better cosmetic outcomes than group B in the MVSS (1.53±1.22 vs. 3.68±1.84), 5-point patient satisfaction score (4.08±0.89 vs. 3.18±1.01), and complication rates (11.8% vs. 36.4%), respectively (p<0.05). Secondary anetoderma, tent sign, calcification, and late regressive stage (evolutionary stage IV) were more common in group B, (p<0.05). Moreover, evolutionary stages showed a positive correlation with mean MVSS (r=0.670, p<0.05).

Conclusion

Early excision (disease duration ≤12 months) provides superior cosmetic outcomes compared to delayed procedures. Early recognition, diagnosis, and management for pediatric pilomatricomas is important to improve overall cosmetic outcomes.

Pilomatrixoma with Atypical Features: A Case Report

Pilomatrixoma is an uncommon, benign tumor with differentiation towards both the hair matrix and cells arising in the cortex, most frequently appearing in the first or second decade of life. In rare instances, pilomatrixomas can show malignant transformation. Pilomatrix carcinoma is extremely uncommon and has traditionally been considered a tumor of low malignant potential; however, a high local recurrence rate has been reported. There is a paucity of literature on these lesions, with only a few reports describing the spectrum of malignant changes seen in these lesions. In this case report, we present a case of pilomatrixoma in an adult patient showing atypical features. While the tumor is small, there are focal features that suggest progression to malignancy, but do not fulfill the criteria for pilomatrix carcinoma. These focal atypical features include a focal infiltrative pattern at the periphery, with a variable cytological atypia and an increased mitotic rate, up to five mitotic events/high-power field. Irregular foci of central necrosis (comedonecrosis) were present in several lobules. Some of the features identified were similar to a subset of pilomatrixoma, known as “proliferating pilomatrixoma.” However, our case did not have the diffuse changes or larger size that has been frequently reported in “proliferating pilomatrixoma.” In conclusion, given the lack of focality of the changes, the lesion in our case is best described as a pilomatricoma with atypical features. Furthermore, our case may highlight the need to ensure close clinical follow-up for these lesions with unexpected atypical features that raise concern of recurrence and malignant transformation.

Minimally invasive surgical treatment of pilomatrixoma

BACKGROUND

Pilomatrixoma is a benign skin tumour often presenting as a firm irregular mass in the paediatric population. The most common site is on the head and neck. Traditionally, a wide local excision has been the method of management. We propose an incision and curettage (I&C) technique for an improved cosmetic outcome.

METHODS

A retrospective review of children who underwent I&C for pilomatrixoma was done between January 2010 and June 2020. The I&C technique involved making a small incision over or near the lesion in a discrete location such as behind the hairline and removing the tumour piecemeal. Four to six weeks of routine post-operative follow-up was conducted. Patients and families were also subsequently contacted via a survey to assess for late recurrence, any other complications and ascertain their level of satisfaction with the outcome.

RESULTS

Twenty lesions were removed in 11 patients over this time with a female predominance (seven) and most lesions were on the face (11). No patients had a recurrence in a mean follow-up time of 6 years (1-10 years). All parents are very satisfied with the cosmetic result.

CONCLUSION

I&C may be an effective and cosmetically pleasing method to removing pilomatrixoma.

Clinical analysis and review of literature on pilomatrixoma in pediatric patients

Background

Pilomatrixoma is a benign tumor that originates from the hair follicle matrix. It usually presents as a hard, slow growing, solitary mass that can be easily misdiagnosed as other skin masses. The aim of this study was to clinically analyze a case series of pilomatrixoma in pediatric patients from Korea.

Methods

A total of 165 pediatric patients from 2011 to 2018 with a histological diagnosis of pilomatrixoma were included. A retrospective review was performed using the electronic medical records, including patient demographics, number and location of the mass, clinical and imaging presentation, and postoperative outcomes.

Results

There were 61 male and 104 female patients with 152 solitary and 13 multiple pilomatrixomas. Among solitary pilomatrixomas, the lesion commonly occurred in the head and neck (84.2%), followed by upper limbs (11.2%), lower limbs (3.3%), and trunk (1.3%). The pilomatrixoma lesion presented as the following types based on our clinical classification: mass (56.02%), pigmentation (25.31%), mixed (12.65%), ulceration (4.82%), and keloid-like (1.2%). Ultrasonography showed a high positive predictive value (95.56%). There were no specific complications observed except for two cases of recurrence.

Conclusion

Pilomatrixoma has various clinical feature presentations and commonly occurs in the head and neck. Ultrasonography is a helpful diagnostic tool. Surgical removal of the lesion is the main treatment method with a low recurrence rate.

Bilateral Cervical Pilomatricoma: A Diagnostic Dilemma for the Pediatric Otolaryngologist

Pilomatricomas are benign skin tumors often encountered by otolaryngologists but frequently misdiagnosed. Although they can occur at any age, they commonly present in children as a discolored superficial lesion adhered to the overlying skin. Accurate preoperative diagnosis is crucial for appropriate management, which is surgical in most cases. Here, we present bilateral pilomatricomas mimicking features of several other diagnoses in a pediatric patient. The patient was successfully treated with surgical excision. This case presented a unique diagnostic challenge, as the lesions exhibited features of several common diagnoses. In general, surgical management of pilomatricoma is curative, and recurrence is rare.

Pseudocystic pilomatricoma: A new variant and review of the literature

A classic pilomatricoma, which usually presents with an asymptomatic, solitary, firm, subcutaneous nodule in the head, neck, or extremities of the paediatric population, is easily diagnosed based on its characteristic clinical and histopathological features. However, its variants often pose particular diagnostic challenges to clinicians due to their rarity and diverse clinicopathological features. We present a new pseudocystic variant, manifesting as solid lesions floating in a fluid-filled sac.

Choristoma: Cervical Chondrocutaneous Branchial Remnants

Unilateral cervical chondrocutaneous branchial remnants (CCBRs) are rare, but when present, are typically located over the lateral aspect of the neck along the anterior margin of the sternocleidomastoid muscle. A CCBR in this location is called a choristoma. Here, we describe a choristoma in a 25-year-old female who disclosed a documented diagnosis of Meniere's disease, and an expressed interest in bearing children within the immediate future. She presented with a unilateral swelling, located subcutaneously, midway over the anterior margin of the right sternocleidomastoid muscle. Due to her history, and the risk of possible radiological exposure to her fetus, an ultrasound-based examination of the neck and cardio-abdomino-pelvic organs was performed. Our clinical findings, details of the ultrasound results, and surgical data will be described.

Dermoid Cyst of Submental Region Mimicking Pilomatricoma

Diagnosis of midline neck swellings may give a myriad of options, ranging from ranula, thyroglossal duct cyst, cystic hygroma, cystic lymphangioma, epidermoid, dermoid and teratoid cysts to benign or malignant neoplasms of the mucosa or salivary glands and also rare skin appendage tumours like pilomatricoma or pilomatrix carcinoma. Various pitfalls are encountered in diagnosing these midline swellings as most of the features are overlapping. Careful history and examination have to be complemented with other diagnostic aids such as conventional radiography, ultrasonography, aspiration cytology and computed tomography to arrive at a correct diagnosis. Dermoid cysts in the head and neck are relatively uncommon, present in the midline either above or below the mylohyoid muscle thus differentiating it into sublingual and submental dermoids and can grow to a massive size before presenting symptoms if it breaches the mylohyoid muscle. Pilomatricoma is a skin appendage tumour which presents as midline swelling and is usually diagnosed with careful history and certain pathagnomonic features on fine needle aspiration cytology and ultrasonography. Hereby we are presenting a case of a submental swelling which was diagnosed as a dermoid cyst upon excision but which initially posed a diagnostic challenge because of features of pilomatricoma seen on FNAC.

Giant proliferating pilomatricoma; report of a rare entity

Proliferating pilomatricoma is a benign tumour and a rare variant of pilomatricoma that has the potential for local recurrence if incompletely excised. We report a case of giant proliferating pilomatricoma on the forearm of a 66-year-old woman. This tumour was unusually large and the presence of ulceration and rapid growth raised clinical suspicion of malignancy. The identification of shadow or ghost cells is a good clue to matrical differentiation, which can be confirmed by β-catenin immunostaining.

Review of pediatric head and neck pilomatrixoma

INTRODUCTION

Pilomatrixoma is a benign skin tumor, which is commonly found in the head and neck region. It usually presents as an isolated lesion and rarely undergoes malignant transformation. It is not uncommon for these tumors to be misdiagnosed.

OBJECTIVE

To review the clinical characteristics of head and neck pilomatrixomas in the pediatric population.

METHODS

A systematic review was completed by searching ten databases to identify studies reporting findings on pilomatrixoma in the pediatric population. Eligible articles were independently assessed for quality by two authors.

RESULTS

A total of 17 studies met the inclusion criteria totaling 318 pediatric patients. The age of diagnosis ranged from 3 months to 17 years of age. The female to male ratio was 1.65:1. In 14 articles, in which pilomatrixoma was located in the head and neck region, 76 (25%) lesions were found in the neck while 229 (75%) were present in the head region. Three articles exclusively described ophthalmologic pilomatrixoma. Even though pilomatrixoma presents with classical features, the clinical diagnostic accuracy when confronting this lesion averaged 43%. The definitive treatment was surgical excision with a very low recurrence rate.

CONCLUSION

Head and neck pilomatrixoma in the pediatric population has a typical presentation with a low clinical diagnostic accuracy. Awareness of this lesion and its clinical appearance can improve its diagnosis. We hereby suggest a management algorithm for suspected pilomatrixoma.

Proliferating pilomatricoma--Case report

Proliferating pilomatricoma is proliferative, rare tumor variant of pilomatricoma. It is a benign neoplasm of hair matrix that can have potentially involve local recurrence. We report the case of a 60-year-old man who presented an asymptomatic nodule on the scalp. Histological exam demonstrated a basaloid epithelium at the periphery, filled with eosinophilic cornified material containing shadow cells. The tumor was excised and there was no evidence of recurrence one year later.

Pilomatrixoma masquerading as metastatic adenocarcinoma. A diagnostic pitfall on cytology

Pilomatrixoma (Px) is a relatively uncommon slowly growing, benign skin appendageal tumor with a wide morphological spectrum, and can pose diagnostic difficulties especially in cases with unusual clinical presentation. We report a case of young male who presented with a nodule over anterior abdominal wall, fine needle aspiration cytology (FNAC) revealed predominantly small cells in focal acinar pattern suggestive of metastatic carcinoma; however, histopathological diagnosis was Px. The case highlights the diagnostic pitfalls on cytology due to limited morphology.

Cyto-histopathological and Clinical Correlation of Pilomatricomas: A 4 Year Study

Aim:

The aim of the following study is to characterize the cytological features of pilomatricomas (PMXs) on fine-needle aspiration (FNA) and correlate with the histopathological features.

Materials and Methods:

FNA, histopathological and clinical diagnosis of 12 cases of PMXs were analyzed. Clinical, aspiration findings and histopathological features were correlated with histopathological diagnosis which was taken as the gold standard. A written consent was taken from patients or parents as appropriate. Morphological features of both aspiration as well as histopathological features were graded. The study was duly approved by the Hospital Scientific Review Committee.

Results:

Out of the 7600 cases studied retrospectively over a period of 4 years, only 12 cases were diagnosed as PMXs. These tumors were mainly located in the head and neck region and mostly affected young females (median age 9.5 years). The mean size of these lesions was 0.9 cm. Out of the 12 histopathologically proven cases of PMX, the correct clinical diagnosis was given in only one case while cytopathological diagnosis was achieved in four cases.

Conclusion:

PMX is a rare tumor, which is mostly found in the pediatric age group. The clinical features should be keenly observed. Keeping in mind the diagnostic pitfalls a cytopathologist may encounter, histopathology should be regarded as the gold standard for diagnosis.

Pilomatrixoma - Presented as Hypopigmented Tender Nodule: Diagnosed by FNAC: A Case Report with Review of Literature

Pilomatrixoma (PMX) is a skin appendage tumor of hair matrix origin, which usually occurs on the face or upper extremities. Although the lesion can appear at any age, it is commonly seen in children and is more common in females. Despite being better defined, pilomatricomas continue to be frequently misdiagnosed and are not usually considered in differential diagnoses, either in clinical set-up or during cytological reporting. They typically present as a superficial, firm, solitary, slow-growing, painless mass in the dermis. The overlying skin may be normal or exhibit a bluish-red discoloration or ulceration. We report an 18-year-old girl presented with tender, subcutaneous nodule with overlying skin showing atrophy and hypopigmentation. Clinically, it was diagnosed as neurofibroma and sent for FNAC. We offered precise diagnosis of pilomatrixoma on cytological examination, (where chances of wrong diagnosis are very high) and it was subsequently confirmed by histopathology. We discuss the varied clinical presentations, diagnostic difficulties, and differential diagnoses of PMX.