Pilomatrixoma: A Comprehensive Review of the Literature

Post-traumatic Bullous Pilomatrixoma Exploring the Pathogenesis

ABSTRACT

This report demonstrates the rare variant of bullous pilomatrixoma in a 10-year-old boy who presented with a rapidly growing, red-colored, bullous nodule on his neck after trauma. The exact etiology of this subtype of pilomatrixoma is unclear, but previous studies have suggested that mechanical trauma may trigger its development.

Multiple Follicular Hybrid Tumors Presenting in Association With Myotonic Dystrophy Type 1

ABSTRACT

Follicular hybrid cysts are uncommon entities derived from 2 or more components of the folliculo-sebaceous-apocrine unit. The pathogenesis of follicular hybrid cysts is uncertain; however, they are proposed to derive from the multipotent nature of follicular stem cells. Myotonic dystrophy type 1 is an inherited muscular dystrophy caused by an unstable trinucleotide repeat expansion in the myotonic dystrophy protein kinase gene, notably associated with multiple pilomatricomas. We report a novel case of multiple follicular hybrid tumors presenting in association with myotonic dystrophy type 1. We suspect that multipotent follicular stem cells, under the influence of the hypermutability phenotype present in myotonic dystrophy type 1, contributed to the pathogenesis of multiple follicular hybrid tumors in our patient.

Diagnosis and management in Rubinstein-Taybi syndrome: first international consensus statement

Rubinstein-Taybi syndrome (RTS) is an archetypical genetic syndrome that is characterised by intellectual disability, well-defined facial features, distal limb anomalies and atypical growth, among numerous other signs and symptoms. It is caused by variants in either of two genes (CREBBP, EP300) which encode for the proteins CBP and p300, which both have a function in transcription regulation and histone acetylation. As a group of international experts and national support groups dedicated to the syndrome, we realised that marked heterogeneity currently exists in clinical and molecular diagnostic approaches and care practices in various parts of the world. Here, we outline a series of recommendations that document the consensus of a group of international experts on clinical diagnostic criteria for types of RTS (RTS1: CREBBP; RTS2: EP300), molecular investigations, long-term management of various particular physical and behavioural issues and care planning. The recommendations as presented here will need to be evaluated for improvements to allow for continued optimisation of diagnostics and care.

Pilomatricoma Located at the Identical Position in the Right Upper Limb of the Twins: A Rare Case Report

Introduction

Rare studies have reported pilomatricoma in twins, and extremely rare cases showed lesions in the same part of the body position. We reported a case of monozygotic twins with pilomatricoma in the same location on the skin of the right upper extremity.

Case Presentation

Seven-year-old monozygotic twins presented to our department with a palpable, painless, and solid mass in the subcutaneous tissue of the right upper limb. A 1.5-cm diameter nodule was seen on the anterolateral aspect of the right upper extremity of the twins. The node was irregular in shape, and upon palpation, the patients reported no noticeable tenderness. Following the administration of local anesthesia, the twins underwent surgical procedure to excise the solid mass. Finally, they were diagnosed with pilomatricoma based on the clinical and histopathological features. Complete surgical resection followed by primary closure was performed. During a follow-up period of three years, there has been no recurrence observed in the twins.

Conclusion

We reported a case of monozygotic twins with pilomatricoma in the same location on the skin of the right upper arm. Our findings underscore the requirement of considering genetic factors in the diagnosis and treatment of the rare conditions.

Clinicopathological and immunohistochemical characteristics of bullous pilomatricoma: a retrospective, single-center study, and comparison with ordinary pilomatricoma

BACKGROUND

Bullous pilomatricoma is a rare variant of pilomatricoma. As it has been published in sporadic case reports, a limited understanding of its clinicopathological characteristics restricts its effective diagnosis and treatment.

OBJECTIVES

This study aimed to analyze the clinicopathological and immunohistochemical characteristics of bullous pilomatricoma to better understand the bullous transformation of pilomatricoma.

METHODS

The authors conducted a retrospective study of 12 patients with bullous pilomatricoma and compared their clinical, histopathological, and immunohistochemical data with those of patients with ordinary pilomatricoma.

RESULTS

Bullous pilomatricoma showed no sex preference, with a mean onset age of 31.2 years. The common sites were the upper extremities and trunk. Bullous pilomatricoma had a shorter disease duration, a larger diameter, and a greater tendency to increase in size than those of ordinary pilomatricoma. Histopathologically, bullous pilomatricoma had a shorter duration, lesser calcification, more mitotic figures, and distinct dermal features from those of ordinary pilomatricoma. Immunohistochemically, the expression of Matrix Metalloprotease (MMP)-2, MMP-9, vascular endothelial growth factor receptor-3 (VEGFR-3), and VEGF-C was elevated.

STUDY LIMITATIONS

The study was retrospective, and the sample size was small.

CONCLUSION

The distinctive features of bullous pilomatricoma potentially result from dermal changes associated with the release of angiogenic factors and proteolytic enzymes. This comprehensive analysis provides novel insights into the clinical features and pathogenesis of bullous pilomatricoma.

Clinical and Pathological Features of Pilomatrixoma in Children: A Retrospective Study

INTRODUCTION

Pilomatrixoma is a benign skin neoplasm that is common in children and is often misdiagnosed. This study aimed to summarize the clinical and pathological features of pilomatrixoma in children.

METHODS

Data on demographic information, clinical and pathological features, diagnosis, and treatment of 171 patients with pilomatrixoma from Shenzhen Baoan Women's and Children's Hospital were collected and analyzed retrospectively.

RESULTS

The mean age of the patients was 5.7 (standard deviation [SD] = 3.9) years old, and there were 2 age peaks (≤1 year old, 5-11 years old) and 2 age valleys (2-4 years old, ≥12 years old). The mean disease course was 9.3 (SD = 14.1) months, 69.0%, 86.5%, and 95.3% of the patients' disease course in 6 months, 12 months, and 24 months, respectively. The mean tumor volume was 0.6 (SD = 1.0) cm3, and 81.3% of the patients' tumor volume ≤1.0 cm3. Tumors were distributed sequentially in the head and neck (77.2%), upper limbs (12.9%), trunk (7.6%), and lower limbs (2.3%). The correct rates of clinical and ultrasonic diagnosis were 50.9% and 38.6%, respectively. The two most common pathological features of pilomatrixoma were shadow cells (99.4%) and basaloid cells (94.7%). There were no significant differences in age, disease course, or tumor volume between the male and female patients (p > 0.05). The age and tumor volume of the patients in different body parts were significantly different (P1 = 3.10E-05 and P2 = 5.60E-05, respectively). The correlation between the disease course and tumor volume was positively significant (p ≤ 0.05). There was a significant correlation between the disease course and tumor volume in patients with tumors at upper limbs (p = 0.03).

CONCLUSION

The age of children with pilomatrixoma presented 2 peaks and 2 valleys. Most patients had disease courses in 24 months and with tumor volumes ≤1.0 cm3. The correct rates of clinical and ultrasonic diagnosis were relatively low. The head and neck were the most common distribution sites of pilomatrixoma, and shadow cells and basaloid cells were the most common pathological features. The tumor volume was positively correlated with disease course in patients with pilomatrixoma.

Post-traumatic pilomatricoma presenting as rapidly enlarging pediatric scalp mass

Pilomatricomas (PM) are benign neoplasms that arise from hair follicle matrix cells. They are one of the most frequently excised pediatric skin masses. A typical clinical presentation is a slow growing, painless, firm, superficial mass in the head and neck of a child. We present a rare presentation of PM. A preschool aged girl presented with an enlarging scalp mass following a history of minor blunt trauma to the area. Two months prior, the child sustained a ground level fall and subsequently developed a painless "bump" at the site of injury on the scalp. The ``bump" was initially the size of a "mosquito bite" and enlarged to the size of a "ping pong ball". Given the rapid progression and history of trauma, there was a broad differential diagnosis. An extensive workup including sonography, computed tomography, MRI, and biopsy were performed. The final pathologic diagnosis was confirmed as pilomatricoma. An atypical presentation of PM in a child can mimic a wide variety of pathology. Our case demonstrates unusual features of rapid enlargement and preceding trauma. With the widespread use of sonography for evaluation of superficial lesions, the radiologist may be the first to suspect the diagnosis of PM. Knowledge of the typical imaging findings in PM can be valuable, especially in more unusual cases.

Pathophysiology, Histopathology, and Differential Diagnostics of Basal Cell Carcinoma and Cutaneous Squamous Cell Carcinoma-An Update from the Pathologist's Point of View

Basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC) are the most frequently occurring non-melanocytic skin cancers. The objective of our study is to present the pathophysiology of BCC and cSCC and its direct relationship with the histopathological diagnostics and the differential diagnostics of these types of cancer, based on the morphological characteristics, immunohistochemical profile, and genetic alterations. The qualitative study was based on emphasizing the morphological characteristics and immunohistochemistry profiles of BCC and cSCC and the differential diagnostics based on the tissue samples from the Clinical Pathology Department of Mures Clinical County Hospital between 2020 and 2022. We analyzed the histopathological appearances and immunohistochemical profiles of BCC and cSCC in comparison with those of Bowen disease, keratoacanthoma, hyperkeratotic squamous papilloma, metatypical carcinoma, pilomatricoma, trichoblastoma, Merkel cell carcinoma, pleomorphic dermal sarcoma (PDS), and melanoma. Our study showed the importance of the correct histopathological diagnosis, which has a direct impact on the appropriate treatment and outcome for each patient. The study highlighted the histopathological and morphological characteristics of NMSCs and the precursor lesions in HE and the immunohistochemical profile for lesions that may make the differential diagnosis difficult to establish.

Integrating vascularity into the pattern classification of pilomatricomas on ultrasound provides a more competent approach for discriminative evaluation

BACKGROUND

Pilomatricoma has various manifestations on color Doppler ultrasound, and a differential diagnosis is challenging. The objective of this study was to investigate which characteristics of skin lesions on color Doppler ultrasound are effective in distinguishing pilomatricoma from epidermoid cyst and dermatofibrosarcoma protuberans.

MATERIALS AND METHODS

Records of patients with pilomatricomas (n = 63), epidermoid cysts (n = 76), and dermatofibrosarcoma protuberans (n = 19) who underwent color Doppler ultrasound evaluation and surgical excision were reviewed. The anatomical distribution and color Doppler ultrasound characteristics of these lesions were analyzed. The 63 pilomatricomas were categorized into five types based on their color Doppler ultrasound characteristics, and the roles of these five types in the differential diagnosis of the aforementioned diseases were studied.

RESULTS

Pilomatricomas, epidermoid cysts, and dermatofibrosarcoma protuberans exhibited some similar characteristics. Dominantly markedly hyperechoic or hyperechoic appearance, posterior acoustic shadowing, and the presence of vascularity were the major characteristics of pilomatricomas. The pilomatricomas could be categorized into five types, with type II having a diagnostic performance of sensitivity of 65.08%, specificity of 98.95%, area under the receiver operating characteristic curve (AUC) of 0.743, positive predictive value of 97.62%, and negative predictive value of 81.03% for the diagnosis of the aforementioned skin diseases.

CONCLUSION

A combination of dominantly markedly hyperechoic or hyperechoic appearance, posterior acoustic shadowing, and the presence of vascularity exhibits higher diagnostic performance for the differential diagnosis of pilomatricomas, epidermoid cysts, and dermatofibrosarcoma protuberans.

Massive Pilomatrixoma of the Scalp: A Case Report

Pilomatrixoma, also called epithelioma of Malherbe, is a benign neoplasm derived from hair follicle matrix cells. It usually presents as a solitary mass in the head and neck region and is more frequent in children and young adults, females, and the Caucasian population. Lesions equal to or greater than 5 cm are categorized as giant pilomatrixomas. We present a case of a 75-year-old female, with no known medical history, who was brought to the emergency department (ED) after falling on the street. She had a giant soft head tissue tumor, severe anemia due to intralesional chronic small hemorrhages and folates and cobalamin deficiencies, and delirant speech. The anatomopathological result of the biopsy of the tumor revealed to be a pilomatrixoma. The patient was then referred to plastic surgery, with complete excision of the tumor. After surgery, she was transferred to the psychiatric team, who assumed the delirant speech to be in the context of schizophrenia. She was discharged four months after admission.

Dermatologic Review in Pediatric Vascular Lesions

Vascular anomalies (VAs) can be present in any organ; however, the skin being the largest one, it is there where many of them are evident; some are visible at birth, others develop throughout life. Pediatric dermatologists are specially trained to distinguish VAs from their mimickers, which require different treatments and may harbor distinct prognoses. We resume the diagnostic and therapeutic tasks of pediatric dermatologist at our vascular anomaly clinics, as well as the differential diagnoses of mimickers of VAs.

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.

Confused subcutaneous nodules in children: Differential diagnosis of pilomatricoma in children

BACKGROUND

Pilomatricoma is a common but easily misdiagnosed tumor in children.

AIMS

To differentiate pilomatricoma from other common subcutaneous nodules in children.

PATIENTS/METHODS

Misdiagnosed subcutaneous nodules in four children were recorded.

RESULTS

A red mass on a 7-year-old boy's head which had been misdiagnosed pyogenic granuloma was proved to be pilomatricoma. A red mass on an 8-month-old boy's face which had been misdiagnosed infantile hemangioma also turned to be pilomotricoma. A red mass on a 21-month-old girl's breast, which had been misdiagnosed pilomatricoma, was proved to be infantile myofibroma. A subcutaneous nodule under a 13-month-old girl's armpit, which had been misdiagnosed pilomatricoma, turned to be BCG-associated lymphadenitis.

CONCLUSIONS

When a child with a subcutaneous nodule attends, pilomatricoma, vascular tumors, fibrous tumors, and BCG-associated lymphadenitis should be considered.

Spatial transcriptomics of a giant pilomatricoma

Pilomatricomas (PMs) are common benign adnexal tumors that show a predilection for the head and neck region and are characterized at the molecular level by activating mutations in the beta-catenin (CTNNB1) gene. Giant PMs are a rare histopathological variant, according to the World Health Organization, which are defined by a size greater than 4 cm and are reported to show upregulation of yes-associated protein compared to PMs of typical 1-3 cm size. We describe the case of a 67-year-old man with an 8 cm giant PM involving his temporal scalp, whose PM we characterized by 10X spatial gene expression analysis. This revealed five total transcriptomic clusters, including four distinct clusters within the giant PM, each with a unique transcriptional pattern of hair follicle-related factors, keratin gene expression, and beta-catenin pathway activity.

Pilomatricoma on the Sole Following Wart Treatment

Pilomatricoma is a benign skin tumor that arises from hair follicle stem cells. It typically presents in the facial region and rarely involves the palms and soles. A 15-year-old boy presented with a solitary tender nodule on the left sole. He had a history of plantar warts on the same site and had received multiple treatments including cryotherapy and intralesional bleomycin injection for nine months. Excisional biopsy was performed, and the specimen showed a well-demarcated mass in the deep dermis with basaloid cells undergoing abrupt keratinization. Ghost cells were seen with calcification. Based on these findings, he was diagnosed with pilomatricoma on the sole. We report a case of pilomatricoma, which developed on a site without hair follicles.

Multiple giant pilomatricomas of the scrotal: A rare case report from Syria

Pilomatrixoma, also known as calcifying epithelioma of Malherbe, is a cutaneous tumor originating from the hair matrix that commonly affects children. Pilomatrixoma is usually solitary and most commonly found on the face, neck, and upper torso, while the scrotum is considered a very rare site. We report a rare location and manifestation of pilomatrixoma as multiple, large, firm, calcified scrotal masses in a 32-years old man. An excisional biopsy was performed, and the diagnosis was confirmed.

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.

A Rapidly Growing Forearm Pilomatricoma in an Elderly Patient

Pilomatricoma is a benign skin tumor of epithelial hair matrix cells that typically presents as a solitary nodule on the head or upper trunk. It occurs most often in children and young adults. While considered uncommon in middle-aged and elderly patients, there are reports of elderly patients with histopathologically diagnosed pilomatricomas; however, these cases primarily occurred on the face. We present a case of an 88-year-old female with a history of non-melanoma skin cancer who presented with a new, rapidly enlarging, biopsy-proven pilomatricoma on the forearm. This case highlights a unique age of onset and location for this skin tumor, suggesting that pilomatricomas are not limited to children and young adults and should be considered in the differential diagnosis of rapidly growing skin lesions in elderly patients. Diagnosis should be confirmed with biopsy in elderly patients, as pilomatricomas may mimic malignant skin lesions.

Diagnostic aid to subepidermal calcified nodule with dermoscopy and reflectance confocal microscopy: a case report

BACKGROUND

Subepidermal calcified nodule (SCN) is a type of calcinosis cutis that usually occurs in children. The lesions in the SCN resemble those of other skin diseases, such as pilomatrixoma, molluscum contagiosum, and juvenile xanthogranuloma, leading to a high rate of misdiagnoses. Noninvasive in vivo imaging techniques, represented by dermoscopy and reflectance confocal microscopy (RCM), have dramatically accelerated skin cancer research over the past decade, and their applications have greatly expanded into other skin disorders. However, the features of an SCN in dermoscopy and RCM have yet to be reported previously. Combining these novel approaches with conventional histopathological examinations is a promising method for increasing diagnostic accuracy.

CASE PRESENTATION

We report on a case of SCN of the eyelid diagnosed with the aid of dermoscopy and RCM. A 14-year-old male patient who presented with a painless yellowish-white papule on his left upper eyelid was previously diagnosed with a common wart. Unfortunately, treatment with recombinant human interferon gel was not effective. To achieve a correct diagnosis, dermoscopy and RCM were performed. The former showed closely grouped multiple yellowish-white clods surrounded by linear vessels, and the latter exhibited hyperrefractile material nests at the dermal-epidermal junction level. The alternative diagnoses were, therefore, excluded because of in vivo characterizations. Subsequent surgical excision, histological examination, and von Kossa staining were performed. Pathology showed hyperkeratosis of the epidermis, a downward-directed basal-layer expansion, and small amorphous basophilic deposits scattered throughout the papillary dermis. The von Kossa staining confirmed calcium deposits in the lesion. An SCN was then diagnosed. During the 6-month follow-up, no relapse was observed.

CONCLUSIONS

Patients with SCN could benefit from dermoscopy and RCM, which help achieve an accurate diagnosis. Clinicians should consider the possibility of an SCN for an adolescent patient with painless yellowish-white papules.

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.

Commonly Misdiagnosed Facial Lesion: Pilomatricoma

Pilomatricoma, also known as Pilamatrixoma or Malherbe's calcifying epithelioma, is a benign skin tumour with a bimodal age distribution between the paediatric and elderly age groups. Although it was previously thought to be rare, recent studies have revealed that it is quite common. Typically, pilomatricoma is diagnosed following histopathological examination of the lesion as it is frequently misdiagnosed with other types of skin pathology. In our case, the child presented with painless swelling of the left infraauricular region. The initial cytology and imaging were unable to provide a definite diagnosis. An excision biopsy was done, and a histopathological examination was suggestive of Pilomatricoma. Therefore, Pilomatricoma ought to be considered in the differential diagnosis of head and neck lesions in hopes of providing a better understanding on this pathological lesion.

A rapidly growing pedunculated pilomatrixoma of the eyelid

A pilomatrixoma is a benign tumor originating from a hair follicle that most frequently occurs in the head-and-neck region. It usually presents as a subcutaneous, slow-growing, nodular, painless firm mass. There are few reported cases on eyelid pilomatrixoma. We reporting an unusual presentation of a rapidly growing pedunculated eyelid pilomatrixoma in a 29-year-old female patient. Surgical excision was performed, and histological examination showed a cavity containing proliferating cords of basaloid cells differentiated into eosinophilic keratinized shadow cells confirming the pilomatrixoma diagnosis. Only a few cases with pedunculated eyelid masses have been reported in the literature; pedunculated lesions can be misdiagnosed as vascular tumors or malignancies. Therefore, pilomatrixoma should be considered in the differential diagnosis of such a presentation. A complete excisional biopsy of the mass is diagnostic and therapeutic.

Bullous Pilomatrixoma After COVID-19 Vaccination

Pilomatrixoma, or calcifying epithelioma of Malherbe, is a benign tumor with differentiation toward the hair matrix cells and is one of childhood's most common epithelial tumors. Bullous pilomatrixoma has an extremely low incidence of occurrence, usually appears in the upper extremities, and is frequently associated with trauma. We report the case of a bullous pilomatrixoma in a patient with a rapid-growing neoformation one month after receiving a coronavirus disease 2019 (COVID-19) vaccine in his left upper arm, and we discuss whether the bullous appearance is part of the biology of the tumor or a secondary anetoderma.

The stone beneath my skin: Pilomatricoma in a young Nepalese girl

Introduction

Pilomatricoma is a rare and benign tumor affecting children and adolescents. It originates from the matrix cells of hair follicles, the usual sites being head-neck and upper extremities. Due to its rarity, it is often misdiagnosed delaying definitive treatment. We report a case of pilomatricoma over the left gluteal region in a young Nepalese girl that was initially thought to be a calcified granuloma.

Case presentation

A six-year-old girl presented with a painful swelling over the left buttock for one year that was gradually increasing in size. On examination, a solitary, well-circumscribed, tender swelling with hard consistency and a bumpy irregular surface measuring 3 × 2 cm was noted over the subcutaneous plane of the left gluteal region. Surgical excision of the mass was done which demonstrated features of pilomatricoma on histopathological examination (HPE). She recovered and remained disease-free at one year follow-up.

Conclusion

This case highlights one of the handful presentations of pilomatricoma involving the buttock. Pilomatricoma is rarely considered a differential diagnosis of benign masses, the diagnosis of which is ascertained mostly after an HPE of the excised specimen. Surgical excision with clear margins is not only diagnostic but therapeutic in most situations.

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.

Multiple pilomatricomas in a child with xeroderma pigmentosum: Coincidence or association?

The association of multiple pilomatricomas with xeroderma pigmentosum has not been described. We report a case of a child with multiple pilomatricomas and photosensitivity who was found to have a pathogenic variant in exon 4 of XPA and a likely pathogenic variant in COL6A1.

Unexpected diagnosis of a pilomatrixoma in an infant: a case report

Pilomatrixomas are a benign tumour of the hair follicle.1–4 Prevalence is estimated to be less than 1 per cent of all benign skin tumours.1,3 Pilomatrixomas present as small, solitary, slow-growing subcutaneous nodules.1,3 Lesions present on the head and neck, with the face the most commonly affected.3 They are more common in adolescent years, and have a female predominance.3 Less than 10 per cent of pilomatrixomas present in patients younger than two years2 with a recent systematic review of 2189 pilomatrixomas revealing an age range of five months to 97 years.3 This case report reaffirms the need for a vigilant approach when managing paediatric skin lesions, particularly those that do not follow the expected course.

Giant pilomatrixoma with bullous appearance on the back: a case report and discussion of misdiagnosis

Pilomatrixoma is a benign asymptomatic skin tumor that forms from hair follicle matrix cells. Most are under 3 cm in diameter and occur on the head, face, or neck. Bullous appearance is very rare in pilomatrixoma. In this case report, we present a case of bullous pilomatrixoma of unusual size, region, symptoms, and patient age. It had been misdiagnosed as a keloid and as dermatofibrosarcoma protuberans. Early treatments were ineffective. The patient approached our outpatient facility and underwent excision. He was then diagnosed with pilomatrixoma by pathological examination. The clinical appearance of this case was quite difficult to diagnose, even MRI and B-ultrasonic examinations provided limited diagnostic evidence. Given the revelations from this case, we reemphasize the importance of performing a biopsy (if patients refused operation or preferred conservative treatment) before any invasive treatment to minimize economic or time loss of patients who have difficulties in diagnosis.

Pediatric chest wall masses: spectrum of benign findings on ultrasound

A palpable finding along the chest wall is a frequent indication for pediatric US. Accurate identification of benign lesions can reassure families and appropriately triage children who need follow-up, cross-sectional imaging, or biopsy. In this pictorial essay, we review chest wall anatomy, illustrate US techniques and discuss key US imaging features of common benign lesions and normal variants.

Clinicopathological Features of 19 Eyelid Pilomatrixomas

Introduction

Pilomatrixoma is a relatively rare, benign tumor arising from the hair root matrix. It is found frequently on the head and neck, with most involving the eyebrow in the periocular region. In contrast, eyelid pilomatrixoma is less common, and often clinically misdiagnosed. Here, we present clinical and histological data from 19 pilomatrixomas arising in the eyelid.

Methods

The study represents a retrospective study of eyelid pilomatrixoma diagnosed at our institution since 1981. All slides were reviewed, and demographic as well as clinical data were obtained.

Results

Patient ages ranged from 2 to 63 years (mean 24 years), including 12 (63%) females and 7 (37%) males. Eight (42%) and 4 (21%) cases arose in the first and second decades of life, respectively. Upper eyelid involvement was found in 14 (74%) of cases. Microscopically, the tumors were characterized by basaloid and shadow cells accompanied by calcification and foreign body giant cells.

Conclusions

Eyelid pilomatrixoma is rarely suspected clinically, and can be mistaken for cyst, chalazion, sebaceous carcinoma, and other tumors. Physicians should consider the possibility of pilomatrixoma in the eyelid area, especially in children or young female patients. Complete excision is curative, and diagnosis can generally be established by histopathological examination.

[Benign skin neoplasms in children]

There are many different types of skin neoplasms in children and most are benign. Dermatologists should be able to differentiate between the various types of benign skin neoplasms and be able to recommend optimal treatment to concerned patients. Surgical removal of benign skin neoplasms is often the only treatment option. The aim of this paper is to provide a general overview of epidermal lesions (e.g., inflammatory linear verrucous epidermal nevus [ILVEN], nevus sebaceous), tumors of the epidermal appendages (e.g. pilomatrixoma), cutaneous neoplasms (e.g. angiofibroma), fibromatoses (e.g., knuckle pads), tumors comprised of fat, muscle, or bone tissue (e.g., osteoma cutis, subungual exostosis), epidermal cysts and pseudocysts, and pathologic fibrosis reactions after dermal injury (keloid). Scientific data are scarce and only in the last decade has it been possible to perform histopathological examinations and genetic studies together with detailed phenotyping to gain new understanding of the pathogenetic mechanisms.

Ki67/MART1 and p63/SOX10 Dual Immunohistochemistry Allows a Correct Interpretation of the Melanocytic Component in the Diagnosis of Pigmented Pilomatricoma

Pilomatricoma is a relatively common benign cutaneous adnexal tumor and a well-recognized entity, while its pigmented variant is far less common and less reported. Its estimated frequency ranges from 11 to 24%, according to a limited number of published case series. This article describes the case of a 42-year-old man presenting a firm subcutaneous nodule of the periareolar region. Histopathologic examination revealed a cystic lesion composed of matrical and supramatrical cells accompanied by a foreign body granulomatous cell reaction. Interestingly, a hyperpigmented area with numerous hyperplastic melanocytes and few mitoses was detectable. In order to assess the cell lineage of the mitotically active component in the hyperpigmented area, double immunohistochemistry with Ki67/Mart1 and p63/SOX10 was performed. Pigmented pilomatricoma is an underrecognized, underreported variant, and double immunohistochemistry stain is an effective tool in providing the correct interpretation of the proliferative activity in the different cellular populations.

Immunohistochemical Localization of Phosphorylated and Unphosphorylated Form of β-catenin With Regard to Shadow Cell and Squamous Differentiation in Cutaneous Pilomatricoma

Pilomatricoma usually contains a mutation in CTNNB1 that encodes β-catenin (BC). It also shows nuclear accumulation of BC protein, which plays an important role in tumorigenesis of pilomatricoma. In vitro studies have indicated that mutant BC protein is unphosphorylated and shows nuclear accumulation, but this theory has not been confirmed in various tumors with CTNNB1 mutation. We examined immunohistochemical localization of phosphorylated BC (pBC) and unphosphorylated BC (npBC) with regard to the modes of cell death or differentiation in 25 cases of pilomatricoma. As for the component showing shadow cell differentiation, BC was detected in cytoplasm/nucleus and along cell membrane in basaloid cells, whereas only in the latter in transitional cells in all cases. Meanwhile, npBC was localized along cell membrane of transitional cells, but not in basaloid cells, nor in nucleus of any components. The components with squamous differentiation also revealed the staining patterns similar to those seen in shadow cell differentiation in some cases. pBC was found in some cell fragments in the amorphous debris containing apoptotic bodies among shadow cell nests. These results suggested that npBC plays an important role in cell adhesion during differentiation and that pBC expression is associated with apoptosis of basaloid cells in pilomatricoma. BC accumulated in the nucleus was not immunoreactive for npBC possibly due to post-translational modification or conformational changes that resulted in loss of or masked antigenicity when BC is assumed to be unphosphorylated.

[Hordeolum and chalazion : (Differential) diagnosis and treatment]

Hordeolum and chalazion are the most frequent inflammatory eyelid tumors. They can occur in association with underlying diseases causing Meibomian gland dysfunction and/or chronic blepharitis. Due to the typical morphological features and clinical course, the diagnosis can mostly be clinically established. The majority of these lesions resolve spontaneously over time. In some instances, surgical intervention is unavoidable. In persistent, recurrent or clinically atypical cases malignant tumors must be excluded as a differential diagnosis by excisional biopsy and histopathological assessment.

Giant Pilomatrical Tumor With Broad Epidermal Components: An Example of Histological Diversity and a Potential Diagnostic Pitfall of Tumors With Pilomatrical Differentiation

ABSTRACT

The diagnosis of pilomatricoma, the most common matrical tumor, is generally straightforward; however, it exhibits diverse histology associated with various morphological stages and several clinical variants, and matrical differentiation can occur in various neoplastic diseases. A 56-year-old man was admitted to our hospital to resect an 11.0-cm skin tumor on his right shoulder. Because of its large size and surface irregularities, including multiple erosions and ulcers, cutaneous malignancies were clinically suspected. Histologically, the tumor formed numerous nodules with marked matrical differentiation in the superficial to deep dermis. Although the tumor was macroscopically asymmetrical and irregular, each nodule was microscopically round-shaped and consisted of basaloid cells without marked atypia, atypical mitoses, or lymphovascular invasion. Immunohistochemically, the tumor cells were positive for beta-catenin, LEF-1, and PHLDA-1, consistent with their pilomatrical differentiation. We diagnosed the case as a giant pilomatrical tumor with uncertain malignant potential, considering its "contradictory" features, namely, the worrisome histoarchitecture, such as the asymmetrical silhouette, but bland-looking cytological appearance. Unlike typical pilomatrical tumors, this tumor contained numerous epidermal components with features similar to those of the dermal components, resulting in a unique macroscopic and histological appearance. Our case broadens the known histological diversity of pilomatrical tumors.

Clinicopathologic analysis of trichoblastoma and comparison with nodular basal cell carcinoma

BACKGROUND

Trichoblastoma (TB) is an uncommon benign follicular tumour for which clinical data is limited since most reports originate from pathology studies.

OBJECTIVE

To describe the clinical aspects of TB.

METHODS

This is an ancillary study of a prospective multicentre cohort of 2710 clinically suspected basal cell carcinoma (BCC), including 935 nodular BCCs. Sixty-two cases were TB: they were analysed and compared to 935 nodular BCCs.

RESULTS

TB mostly occurred in females (61% vs. 43% for BCC, P<0.01) of mean age 63 years. They were located on the head and neck, mainly on the nose and forehead, in 87% of cases. The mean size was 8.1mm, 77% were<10mm (55% of BCCs, P<0.001), 8% were ulcerated (vs. 21% of BCCs, P<0.02), and 47% persisted for more than 1 year (34% of BCCs, P<0.05). Most cases had a clinical presentation similar to nodular BCC, except for 5 small, flat, white papules and 1 anfractuous plaque.

LIMITATIONS

Cases originated from a series of tumours clinically suspected as BCCs.

DISCUSSION

Some 2.6% of tumours clinically diagnosed as BCC are in fact TB. TB occurs on the head, are more frequent in women, and are smaller and of longer duration than BCC. In most cases, clinical diagnosis on clinical grounds is difficult.

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.