Clinical and epidemiological characteristics of pilomatricomas in a Mexican pediatric population.

BACKGROUND: Pilomatricoma is a common benign adnexal neoplasm in children. There are few epidemiological studies on this subject, with most relying solely on descriptive statistics. METHODS: A cross-sectional study conducted in two tertiary hospitals in Mexico City from January 2017 to December 2023. Clinical and electronic records of patients with histopathological diagnosis of pilomatricoma, both sexes, under 18 years old, with any type of present comorbidity were selected. Records of patients with diagnosis not confirmed by histopathology or incomplete records were not included in the study. RESULTS: Fifty-two cases with pilomatrixoma were included in the study, showing a total of 74 lesions. About 23.1% of the cases had multiple pilomatrixomas. 40.4% of the cases experienced pain; this symptom was associated with lesions > 15 mm in diameter and with multiple pilomatrixomas. Risk factors for lesions > 15 mm included age under 8 years, positive tent sign, tumor evolution longer than a year, and a non-classical clinical variety. The head and neck were the most commonly affected areas. The left upper extremity presented larger pilomatrixomas (median 18.5 mm) and occurred more frequently in adolescent patients (mean age 12.1 years) compared to other body areas. CONCLUSIONS: Pilomatrixoma in children shows clinical diversity, with specific findings based on size, number, and anatomical location.

INTRODUCCIÓN: El pilomatricoma es una neoplasia anexial benigna frecuente en la infancia. Hay muy pocos estudios epidemiológicos al respecto y la mayoría solo han utilizado estadística descriptiva. MÉTODOS: Estudio transversal realizado en dos hospitales de concentración de la Ciudad de México de enero de 2017 a diciembre de 2023. Se seleccionaron expedientes clínicos y electrónicos de pacientes con diagnóstico histopatológico de pilomatricoma, ambos sexos, menores de 18 años, con cualquier tipo de comorbilidad presente. No se incluyeron los expedientes de pacientes con diagnóstico no confirmado por histopatología o expediente incompleto. RESULTADOS: Se incluyeron 52 casos con diagnóstico de pilomatricoma que mostraron un total de 74 lesiones. El 23.1% de los pacientes tuvieron pilomatricomas múltiples. El 40.4% experimentaron dolor; este signo se asoció con lesiones de diámetro superior a 15 mm y pilomatricomas múltiples. La edad menor de 8 años, el signo de la tienda de campaña positivo, un tiempo de evolución mayor de 1 año y una variedad clínica no clásica son factores de riesgo asociados con las lesiones mayores de 15 mm. La cabeza y el cuello fueron las áreas más comúnmente afectadas por estos tumores. La extremidad superior izquierda presento pilomatricomas de mayor tamaño (mediana 18.5 mm), y ocurrieron más en pacientes adolescentes (media 12.1 años), en comparación con otras áreas del cuerpo. CONCLUSIONES: El pilomatricoma en niños muestra diversidad clínica. Presenta hallazgos y asociaciones específicas según el tamaño, el número y la ubicación anatómica.

A Hybrid Skin Cyst at an Unusual Location: A Case Report.

Hybrid cysts originate from more than two components of the pilosebaceous unit. The pathogenesis of this cystic lesion remains unclear. Most of the investigated cases have scalp and face predilection. The lesion is predominantly observed in females. We present a case of a 69-year-old woman with a painless cutaneous nodule measuring 0.7 cm on the right calf. After a surgical excision, the histological investigation showed that the normal epidermis was elevated by a deeply encapsulated intradermal cyst, which was lined by two distinct histological types of epithelium with an abrupt transition between them. One-half of the cystic surface consisted of a keratinizing squamous layer with a granular layer and keratin lamellae, while the other half was lined by epithelium showing pilomatricial differentiation. Finally, an extremely rare diagnosis was set of a hybrid cyst.

Pilomatricoma presenting as a giant cutaneous horn in an 8-year-old child: A case report and literature review.

Pilomatricoma is an uncommon benign adnexal tumor of childhood. We report a case of pilomatricoma presenting as a large, recurrent painful cutaneous horn on the neck of an 8-year-old boy treated with surgical excision. On histopathology, classical features of pilomatricoma along with transepidermal elimination and perforation were shown. We propose that perforating pilomatricoma and pilomatrical horn represent equivalent clinical and pathological entities. The diagnosis of perforating pilomatricoma should be considered in pediatric patients presenting with a cutaneous horn.

Retrosynthetic analysis via deep learning to improve pilomatricoma diagnoses.

BACKGROUND: Pilomatricoma, a benign childhood skin tumor, presents diagnostic challenges due to its manifestation variations and requires surgical excision upon histological confirmation of its characteristic cellular features. Recent artificial intelligence (AI) advancements in pathology promise enhanced diagnostic accuracy and treatment approaches for this neoplasm. METHODS: We employed a multiscale transfer learning model, initiating the training process at high resolutions and adapting to broader scales. For evaluation purposes, we applied metrics such as accuracy, precision, recall, the F1 score, and the area under the receiver operating characteristic curve (AUROC) to measure the performance of the model, with the statistical significance of the results assessed via two-sided P tests. Our novel approach also included a retrosynthetic saliency mapping technique to achieve enhanced lesion visualization in whole-slide images (WSIs), supporting pathologists' diagnostic processes. RESULTS: Our model effectively navigated the challenges of global-scale classification, achieving a high validation accuracy of up to 0.973 despite some initial fluctuations. This method displayed excellent accuracy in terms of identifying basaloid and ghost cells, especially at lower scales, with slight variability in its ghost cell accuracy and more noticeable changes in the 'Other' category at higher scales. The consistent performance attained for basaloid cells was clear across all scales, whereas areas for improvement were identified in the 'Other' category. The model also excelled at generating detailed and interpretable saliency maps for lesion visualization purposes, thereby enhancing its value in digital pathology diagnostics. CONCLUSION: Our pilomatricoma study demonstrates the efficacy of a deep learning-based histopathological diagnosis model, as validated by its high performance across various scales, and it is enhanced by an innovative retrosynthetic approach for saliency mapping.

Multiple, giant lymphangectatic pilomatricomas: A rare clinical entity.

This case highlights the rare and atypical presentation of giant, multiple pilomatricomas (PMs) with a pseudo-bullous appearance and lymphangiomatous pathology. It underscores the importance of considering PM in the differential diagnosis of atypical lesions, especially those mimicking cystic or hemorrhagic malignant conditions, to prevent misdiagnosis and ensure appropriate management.

A Retrospective Study of the Clinicopathological Characteristics of Approximately 1,600 Pilomatricomas Treated at a Single Institution.

BACKGROUND: First reported by Malherbe in 1880, pilomatricoma is a common benign skin tumor generally believed to occur mainly in children and adolescents. We conducted this study to better define the characteristics of pilomatricoma and compare our findings with current knowledge. METHODS: Patients diagnosed pathologically with pilomatricoma from 2016 through 2020 at Nippon Medical School Musashi Kosugi Hospital were included (1,559 patients, 1,590 tumors). Clinicopathological characteristics were analyzed. RESULTS: The male to female ratio was 1:1.6, and the most common tumor site was the upper limbs (33.7%). Preoperative diagnosis was correct in 48.5% of the patients, and their average age at resection was 33.5 years. Resection was carried out in 70% of the patients within 1 year, but time to resection was more than 1 year in the other 30%. Pathologically, squamous stratifying keratinocytes were observed in 41.7% of the patients, cells with a large pale pink cytoplasm in 38.9%, hair papilla-like structures in 33.9%, ossification in 15.7%, trichohyalin granules in 11.9%, and aggregations of follicular germinative cells in 7.8%. Of the chronological and morphological stages proposed by Kaddu (stage 1: early, stage 2: fully developed, stage 3: early regressive, stage 4: late regressive), stage 3 was the most common (70.6%). CONCLUSION: Pilomatricoma is more common in females, regardless of ethnicity or age, but the tumor location in the upper limbs commonly observed in Japanese patients may indicate ethnic differences. Pathologically, the fact that cells linked to follicular differentiation are observed suggests that pilomatricoma is a complex panfollicular neoplasm. Time to resection appears to correlate with Kaddu stages. Factors such as age, location, sex, depth, and stage may affect the pathological features of this tumor.

Pilomatricoma of the calf: a case report and review of literature.

Introduction and importance: Pilomatricoma (PMC) is a benign adnexal dermal or subcutaneous tumor, which is derived from immature hair matrix cells. It makes up around 20% of all tumors related to hair follicles in most series and is therefore the most common hair-follicle neoplasm. Nevertheless, diagnosing it remains intricate due to the prevalence of more frequent pathological conditions in soft-tissue. Anatomopathological examination proves to be a valuable asset, offering a definitive and certain diagnosis. Case presentation: The authors hereby present a case of a 17-year-old patient with no medical history, who was referred to our medical unit subsequent to the emergence of swelling in the right calf. MRI results highlighted the presence of a subcutaneous nodule situated on the right calf. Following a percutaneous biopsy, the diagnosis of PMC was definitively confirmed. A successful surgical excision of the tumor was performed, and the postoperative progress demonstrated positive outcomes. Clinical discussion: PMC usually appears as flesh-colored to white, firm papules or papulonodules that may have an overlying pink to blue hue. MRI plays a crucial role in diagnosis, as it delineates the tumor's extent in relation to the skin and muscle compartments. Preoperative histological confirmation is essential to rule out other potential diagnoses and precisely establish the required resection margins. Conclusion: PMC is an infrequent occurrence in general surgery departments. General surgeons should, however, be well-acquainted with this benign tumor while assessing soft-tissue masses.

Pilomatricoma: A Case Report.

Pilomatricoma is one of the rare skin benign neoplasms arising from the matrix cells of hair follicles. We report the case of a 17-year-old female who had a swelling over the medial surface of the right ear lobule, which was determined to be an epidermal inclusion cyst by radiological and clinical examination. Over the period of eight days, it grew to 2 × 2 cm. A well-defined encapsulated lesion with thick cellular debris was found on an ultrasonography of the local region. Under local anesthesia, the patient had a cyst excision. Early detection by ultrasonography is beneficial in skin lesions to confirm if they are benign or malignant. Complete excision of the cyst is the treatment in order to limit the morbidity and lower the aggressive behavior. In this case, we came to a diagnosis after a histopathological examination, confirming it as a pilomatricoma. Due to its rarity, it is often misdiagnosed.

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.

Pediatric Type of Early Pilomatricoma of the Auricle: A Case Report.

Pilomatricoma is a benign adnexal neoplasm that has been associated with malignancy transformation. Yet, it is not considered as pre-malignant lesion. It is divided into pediatrics type and adult type on the age of occurrence and based on stage of presentation it can described as early and late. We hereby report a 16-year-old female patient with Early-Stage Pediatric Type Pilomatricoma of the Auricle. Supplementary Information: The online version contains supplementary material available at 10.1007/s12070-024-04584-0.

Dermotoscope assisted diagnosis of adolescent bullous pilomatricoma: six case reports.

BACKGROUND: Pilomatricoma (PM) is a cutaneous benign neoplasm derived from the hair matrix. It clinically presents as a solitary and firm nodule overlying normal epidermis and is usually not easy to be noticed at early stage. Nevertheless, when special bullous lesion occurs in a short time or even ulcerates, preoperative diagnosis by a dermatologist is often challenging especially when the pediatric patients refuse biopsy. CASE PRESENTATION: We present six bullous PM cases and particularly conduct correlation analysis on the dermotoscopy and histopathology detection data. The basic information, medical history, symptoms and lesion morphology results of the patients were also provided. We found that the incidence of bullous PM was higher in females than in males, and most patients were adolescents and the predilection location seem to be consistent in the vaccine injection site. The dermatoscopic features of bullous PM reported were luminous yellow structure below, with gray-blue homogeneous areas and branched capillary. The histological features were consistent with PM, and evident epidermis bullae were above the tumor with extraordinary dilation of lymphangion in the upper dermis. The patients described in this study were Chinese patients in Han population included 4 females and 2 males, coincidentally, they are almost teen-age, respectively are 5,11,17,19,21,22 year-old. CONCLUSIONS: This study reported and analyzed the dermotoscopy and clinical characteristics of bullous PM, dermotoscopy may guide as a rapid and reliable technique in bullous PM diagnosis.

Pilomatrix Carcinoma: A Benign-Mimic with Malignant Consequences - A Case Report and Review of the Current Literature.

Introduction: Pilomatrix carcinomas (PMXCs) are uncommon, locally aggressive tumors with high recurrence rates, metastatic potential, and fewer than 130 cases reported in the literature. Typically, they present as an unassuming, firm, dermal swelling and therefore are frequently mistaken for more common, benign masses, leading to undertreatment which can cause local invasion and metastatic spread. Diagnosis relies on excision with pathologic analysis; however once diagnosed, there are no current recommendations to guide treatment or surveillance for recurrence or metastases. Case Presentation: Here, we present a case of one of these rare tumors. Our case describes a 1.5 × 2.5 cm firm, mobile mass at the supraorbital rim in an otherwise healthy, young patient. Prior to removal, we suspected a benign pathology; however, excision proved difficult and pathologic diagnosis was consistent with PMXC. Following discussion with tumor board, decision was made to perform Mohs micrographic surgery and staging via CT scans with regular follow-up and surveillance scans. Conclusion: PMXCs are exceedingly rare diagnoses and present like many benign lesions. Therefore, we elected to document this case to encourage providers to keep these biologically aggressive tumors on their list of differential diagnoses in an unsuspecting mass, as well as to provide our own recommendations for treatment and screening for recurrence and metastatic spread.

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.

Facial Soft Tissue Lesions in Children.

Facial soft tissue lesions in children are often classified based on their structure or cellular origin and can be benign or malignant. This review focuses on common facial soft tissue lesions in children, their clinical morphology, natural history, and medical and surgical management, with an emphasis on those considerations unique to soft tissue lesions present at this anatomic site.

Pilomatrix carcinoma of the lower extremity: A rare case report and literature review.

INTRODUCTION: Pilomatrix carcinoma (PC) is a rare skin malignancy of the hair follicles matrix that tends to be locally aggressive with 10-16 % risk of metastasis mostly to the pulmonary and lymphatic system. There are no clear protocols for the management of PCs, however surgical intervention with clear margins has been highly considered in PC management to decrease risk of recurrence. CASE PRESENTATION: A 40 year-old male patient presented to our clinic to evaluate an asymptomatic, slow-growing nodule localized on his left thigh. A CT scan revealed a well-defined, enhanced lesion with microcalcification. "En bloc" surgical resection of the lesion was performed and histopathology confirmed the diagnosis of pilomatrix carcinoma. CLINICAL DISCUSSION: Given its rarity, there are no definitive guidelines regarding PC treatment. However, surgical intervention with clear margins including wide local excision or Mohs micrographic surgery has been highly considered. In our case, wide excision of the lesion with clear margins was performed with no evidence of recurrence one year later. CONCLUSION: Given the local aggressive nature of PC, appropriate surgical intervention is essential in decreasing the risk of recurrence. Wide excision with clear margins has been proposed to decrease the risk of recurrence. Additionally, total-body skin examination should be done 2-3 times annually to evaluate for recurrence or metastasis.

A case of AA amyloidosis complicated by proliferating pilomatricoma and a review of the literature.

Although AA amyloidosis is primarily caused by inflammatory conditions, associations between AA amyloidosis and solid cancers have occasionally been described. Herein, we report the case of a 48-year-old man in whom resection of a proliferating pilomatricoma with deposition of AA amyloid resulted in remission of concomitant AA gastrointestinal amyloidosis. A rapidly growing, giant, reddish, ulcerated tumor measuring 16 × 13 cm in size was identified on the upper left arm on a visit to our hospital. Gastrointestinal AA amyloidosis was diagnosed from colorectal mucosal biopsy at the same time, and weight loss and profuse diarrhea were clinically evident. As treatment, the tumor was resected with a 10-mm surgical margin. Histologically, the tumor predominantly comprised a lobular proliferation of basophilic cells peripherally, filled with eosinophilic, cornified material and shadow cells with mitoses observed in basophilic cells. Specimens revealed eosinophilic, homogeneous deposits around tumor nests, which were confirmed as amyloid deposits by positive staining with Congo red stain. These deposits were immunohistochemically positive on staining with anti-serum amyloid A antibody. Collectively, proliferating pilomatricoma with AA amyloidosis was diagnosed. After tumor resection, chronic diarrhea resolved and no amyloid deposition was apparent in colorectal biopsy. It is important to remember that if amyloid deposition is present in a tumor, aggressive tumor excision may alleviate systemic amyloidosis.

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.

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.

Unusual presentation of pilomatricoma: A case report and comprehensive review of the literature.

Pilomatricoma is a benign proliferative lesion of skin appendages that often affects the head, upper limbs, and lower limbs. The clinical appearance of the lesions is that of asymptomatic nodules measuring less than 3 cm. pathologically, these skin lesions show the presence of basaloid cell islands, eosinophilic cytoplasmic cells without nuclei, as well as hemorrhage and calcification. In this study, we present the case of an 8-year-old girl with a 5 × 5 cm skin lesion on the forearm, which lacked the typical firmness associated with pilomatricoma lesions during examination. After biopsy, the lesion was confirmed to be pilomatricoma. Furthermore, we have reviewed studies documenting pilomatricoma lesions with atypical clinical features. Based on reports of different clinical manifestations of pilomatricoma in these studies, we suggest that the clinical diagnosis of pilomatricoma should not be limited to the typical presentation of these lesions. In cases where the lesions exceed 3 cm in size, display cystic characteristics, are painful, or resemble keloids, consideration should also be given to the possibility of pilomatricoma.