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Tetrasomy 9p is a rare genetic syndrome resulting from two additional copies of the short arm of chromosome 9. Symptoms often present in the form of congenital abnormalities including cognitive disabilities, growth retardation, abnormal earlobes, congenital heart disease, and dysmorphia of the skull and face. Current literature suggests patients with tetrasomy 9p may exhibit any combination of these symptoms or, in rare instances, none at all. Although karyotyping, chromosomal microarray, and galactose-1-phosphate uridyltransferase activity analyses are the definitive diagnostic methods used, there remains a need for more robust clinical recognition in cases of mild phenotypic expression. Herein, we present a rare case of mosaic tetrasomy 9p in a long-term survival patient with multiple and recurrent pilomatrixomas, rare benign growths more commonly found in individuals under the age of 20. To our knowledge, only two previous reports have noted concurrent tetrasomy 9p with pilomatrixomas. We are the first to identify this phenotype in an adult tetrasomy 9p patient. Dermatopathology evaluation was conducted to verify our diagnoses. Our aim is to present a unique, additional case suggesting multiple pilomatrixomas as a new defining clinical presentation of mosaic tetrasomy 9p and to review the literature underlying the genetic changes associated with this syndrome.

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., (© 2024. The Author(s).)

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., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Case Report: A 55-year-old male patient developed a mass in the left inguinal area with left lower limb swelling and first visited a local hospital 3 months earlier because of unrelieved pain. An MRI scan suggested left suprapubic branch and left acetabular bone destruction, abnormal soft tissue signals within the iliopsoas muscle of the anterior edge of the left iliac bone, and enlarged lymph nodes in the left iliac fossa and left inguinal region. The patient subsequently underwent left pelvic lesion open biopsy and inguinal lymph node resection biopsy. According to pathological reports, the left inguinal mass was considered to be a malignant tumor of cutaneous accessory origin (pilomatrix carcinoma) with extensive vitreous changes. The suprapupubis branch mass was considered to be a bone metastatic pilomatrix carcinoma. Immunohistochemistry (IHC) revealed a PDL1 combined positive score (CPS) of 8. DNA next-generation sequencing (NGS) showed CDKN2A L65Rfs*53 mutation. The patient received three cycles of gemcitabine and nedaplatin. However, the lesion progressed., Conclusion: Chemotherapy is not effective for treating pilomatrix carcinoma. PDL1 antibodies and CDK4/6 inhibitors might be treatment options for pilomatrix carcinoma., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Abula, Ma, Wang, Peng, Pei and Hu.)

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., (Copyright © 2024 Sociedade Brasileira de Dermatologia. Published by Elsevier España, S.L.U. All rights reserved.)

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.

Background: Pilomatrixoma, also known as calcifying epithelioma of Malherbe, is a benign cutaneous neoplasm that demonstrates differentiation towards the matrix portion of hair follicles. It is the most common benign cutaneous neoplasm in childhood and youth, although it can occur at any age. With a general incidence ranging from 0.001% to 0.0031% of all cutaneous tumors. There is a slight predilection for females, with a female-to-male ratio of 1.15:1., Methods: Observational, descriptive, retrospective, and cross-sectional study conducted using the electronic database of the dermatopathology department of Dr. Manuel Gea González General Hospital, from January 1992 to July 2023. Only cases with a histopathological diagnosis of pilomatrixoma, pilomatricoma, and Malherbe's calcifying epithelioma were included., Results: A total of 200 pilomatrixomas were recorded in 177 patients. The tumor predominantly affected females in the pediatric age group, with an average age of 22.98 years in the studied population. The most common location was the head (periorbital region), followed by the upper extremities and trunk. Upon separating the population into pediatric and adult groups, 111 and 89 cases were identified, respectively., Conclusions: We present a detailed study on pilomatrixomas with a comprehensive overview of the demographic, clinical, and epidemiological characteristics of this benign cutaneous neoplasm. The results revealed robust statistical data highlighting the distribution by age, gender, topography, morphology, accompanying symptoms, and frequency of clinical differential diagnoses. This study significantly contributes to the existing knowledge of pilomatrixomas and serves as a valuable reference for future research and clinical practice., (Copyright: © 2024 Permanyer.)

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., (© 2024 S. Karger AG, Basel.)

Background: As pilomatricoma is a common adnexal skin tumor often occurring in exposed areas, dermatologists focus on minimizing postsurgical scarring., Methods: This retrospective study included patients aged < 19 years who underwent surgical treatment for pilomatricoma at a single university hospital from 2015 to 2021. Patient demographics, tumor characteristics, and surgical outcomes were analyzed according to the surgical methods including punch incision and elliptical excision., Results: Overall, 75 patients and 79 lesions were included in the study. The mean age of the patients was 8.4 years, and 48 patients (64.0%) were females. The face was the most common site of pilomatricoma (51.9%), and within the face, the cheeks were the most common sites. No recurrence was observed in the elliptical excision group, while one case of recurrence (4.5%) was observed in the punch incision group. The mean length of the wound was 2.00 cm in the elliptical excision group, which was longer than that in the punch incision group (0.49 cm; p  < .001)., Conclusions: Considering that surgery is the gold standard treatment for pilomatricoma, punch incision may be useful as an alternative surgical option for pilomatricoma in children.

Pilomatrixoma is a relatively rare benign skin appendageal tumor, often presenting in the pediatric age group as a nodular lesion and most commonly involving the head and neck, making it amenable to primary fine needle aspiration (FNA) diagnosis. We report the clinical and histopathological findings of two cases of pilomatrixoma in children, both of which were initially misdiagnosed as small round blue cell tumors due to high cellularity and misinterpretation of the proliferating basaloid cells. Histopathology revealed basal cell proliferation and mitoses indicating that they were progressive, early lesions. The first case showed membranous positivity for CD99 which prompted a diagnosis of Ewing sarcoma. Awareness of the morphological spectrum including positivity for CD99 and careful evaluation of cell block histology could have averted the misdiagnosis. Pilomatrixoma should be included as an important differential diagnosis when faced with primitive-appearing cells on FNA, especially in children with mass lesions in the head and neck region., (© 2023 Wiley Periodicals LLC.)

Abstract: Melanocytic matricoma is a rare benign pilar tumor characterized by matrical differentiation and interspersed dendritic melanocytes. It may show cellular atypia and brisk mitotic activity. Histological characterization of some lesions may be difficult. In addition, because the reported cases are few and have limited follow-up, there is insufficient experience to define outcome-based criteria for malignancy. Some cases of melanocytic matricoma with more prominent atypia have been reported as malignant, but their clinical behavior is uncertain. We present a melanocytic matricoma with interspersed benign dendritic melanocytes, but moderate basaloid atypia, focally brisk mitotic activity, and atypical mitoses. Despite the apparently good delimitation of this tumor, higher magnification revealed a slightly irregular border. However, overt malignant features such as necrosis, frank asymmetry, deep infiltration, and ulceration were not present. This tumor showed a complex aberrant genomic profile with multiple whole chromosomes or chromosomal arms, losses, and duplications. The tumor mutational burden was high. A loss-of-function alteration in CDKN2A and a loss-of-function mutation in TP53 were also present. This unexpected molecular profile contrasts with the relatively bland histology of the tumor and is in line with the difficulties in microscopic differential diagnosis between melanocytic matricoma and an indolent malignant pilomatrical tumor. We suggest that molecular studies and longer follow-up periods may help to further understand and more precisely categorize borderline pilomatrical tumors with melanocytic hyperplasia., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Abstract: Melanocytic matricoma with atypical features is a rare, biphasic adnexal neoplasm displaying hair matrix differentiation, with only 3 reported cases worldwide. Generally, the lesion comprised a solid matrical and supramatrical cell proliferation, admixed with intermediate cell aggregates with sparse anucleated "shadow cells" and a prominent pigmented melanocytic hyperplasia. We report the case of a 78-year-old man with a slow-growing crusted lesion on the frontal left scalp, which in a matter of 1-2 months became a 0.6 cm well-defined, black purplish exophytic nodule. Histopathologically, the lesion presented a well-circumscribed border with a nodular dermal growth pattern, presenting different architectural features varying from benign pilomatricoma-like changes to atypical features such as moderate-to-high nuclear pleomorphism in both basaloid (matrical/supramatrical) and epidermal (keratinous) components. Strong nuclear and cytoplasmic positivity for β-catenin was observed in matrical cells, whereas prominent cytoplasmic membrane positivity for Melan-A in dendritic melanocytes. Owing to the evidence of atypical cytological features, we propose the "atypical/borderline" category of melanocytic matricoma as part of a possible spectrum among matrical neoplasms. Pathologists should be aware of any atypical histopathological features while reporting cases due to their potential malignant transformation., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

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., (Copyright © 2023 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

Calcifying epithelioma of Malherbe, also known as pilomatricoma or pilomatrixoma, mostly arises in the matrix hair follicle. It generally affects the head and neck, upper extremities, and trunk, with the lower extremities being a rare exception. We hereby present a case of a 31-year-old male patient who presented with a small, firm, subcutaneous mass over the left malleolus, which was provisionally diagnosed as lipoma. Surgical excision was performed, and the histopathology report revealed it to be pilomatricoma of the left malleolus.

Introduction or Background: Pilomatrix carcinoma is a rare malignant neoplasm arising from the root of hair follicles, with only 150 cases described in the world literature. It is most commonly seen in the head and neck region., Case Presentation: We describe a case of malignant pilomatrix carcinoma in a 62-year-old gentleman presenting as a solitary globular mass over the right anterior chest wall along with a brief review of literature., Discussion and Conclusion: Surgical excision with a wide margin is the current standard of care for chest wall pilomatrix carcinoma and is associated with the least recurrence. Role of radiation as definitive treatment of the primary or as adjuvant therapy has not been clearly established.

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.

Melanocytic matricoma is a rarely reported, benign cutaneous adnexal neoplasm composed of epithelial cells exhibiting differentiation towards hair matrix as well as admixed, pigmented, dendritic melanocytes. The proposed malignant counterpart to melanocytic matricoma, malignant melanocytic matricoma (MMM), is even more rare. Here we report a case of a melanocytic matricoma with atypical features in a 92-year-old female with a 1.2-cm pigmented nodule on the right nasal sidewall. Histopathology revealed a well-circumscribed dermal tumor composed of atypical matrical cells with scattered aggregates of anucleate keratinocytes (ghost cells), prominent intratumoral pigment, numerous mitotic figures (88 mitosis/10 high-power field [HPF]), and intermixed dendritic melanocytes. A literature review was performed for MMM to determine if the current case fit diagnostic criteria for this entity. Including the current case, 12 cases of MMM were identified and analyzed to investigate common clinical and histopathologic features. MMM commonly occurred on the head and neck (7/12 cases) of older individuals (median age of 80) with a slight male predominance (male-to-female ratio of 3:1) and on histopathology presented as a multinodular dermal tumor composed of mitotically active (average mitotic rate of >50 mitoses/10 HPF) pleomorphic epithelial cells with foci of ghost cells. Dendritic melanocytes were found throughout the tumor lobules in all cases. Given that only two of 12 cases have exhibited locally aggressive behavior, further study is warranted to determine the true malignant potential of MMM., (© 2022 Japanese Dermatological Association.)

A 23-year-old man presenting with a 1-year history of a lesion of the right cheek. We highlight this case for awareness as this tumour may mimic other benign lesions, such as pilomatrixoma or benign cysts, as it does not have any uniquely identifying clinical or dermoscopic features. Additionally, it is of concern as malignant transformation can occur and therefore surgery should be considered as both for diagnostic and therapeutic benefit., (© 2022 British Association of Dermatologists.)

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.

Abstract: Pilomatrical differentiation can be observed in a variety of benign and malignant tumors, with the most common prototype being pilomatricoma. Pilomatricoma often presents in the deep dermis or subcutis, and the sole involvement of epidermis is extremely rare. In our current case series, specimens from 5 patients were included with an average age of 68 years. All lesions presented as solitary verrucous or keratotic papules on the extremities, with 1 lesion having a prominent horn. All lesions have a variable mixture of basaloid matrical cells and shadow cells, and all lesions express β-catenin (strong nuclear and cytoplasmic), lymphoid enhancer-binding factor 1 within the matrical component, and pleckstrin homology-like domain family A member 1. The histomorphology and immunoprofile of all lesions are of pilomatrical differentiation, confined to the level of the epidermis. Based on these findings and analogous to the terminology used for other benign intraepidermal proliferations (hidroacanthoma simplex and epidermolytic acanthoma), we propose the term "pilomatrical acanthoma" for these rare lesions., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Abstract: Panfolliculomas (PF) are rare, benign, follicular tumors that differentiate toward multiple components of the hair follicle, and several variants have been described. We present a case of a rare pigmented PF presenting on actinically damaged skin in an 83-year-old man, which was clinically concerning for malignancy. This tumor arose near an area of atypical squamous proliferation and has evidence of infundibular, outer root sheath, and matrical differentiation and foci of heavy melanin pigmentation and increased melanocytes. We propose the novel designation of "melanocytic PF," akin to melanocytic matricoma but with panfollicular differentiation., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Skin adnexal tumours (SATs) comprise a diverse range of neoplasms, which are difficult to diagnose clinically. They present in paediatric and adult populations, and may be indicative of an underlying genetic syndrome. There is a lack of recent data on the presentation of these tumours in clinical practice in European populations., Objectives: To characterize the clinical and pathological features of SATs received at a single tertiary centre over a 5-year period., Methods: A retrospective health record audit of SATs received at the Department of Cellular Pathology, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, during the period November 2012 to October 2017 was performed., Results: In total, 107 144 skin cases were received during the audit period. A total of 1615 cases of SATs from 1359 patients were included; 1570 (97·2%) were benign and 45 (2·8%) were malignant. Overall, the average age at presentation was 55 years (range 11 months to 97 years) and the male to female ratio was 0·77 : 1. Sweat gland and hair follicle SATs were most frequently excised; in adults, the most frequent tumour was hidrocystoma, and in children, pilomatrixoma occurred most often. Prebiopsy diagnosis was correct in 28% of cases. Benign SATs are often markers of an associated genetic condition, which warrants improved discrimination of sporadic from genetically related SATs., Conclusions: SATs are difficult to diagnose clinically, and clinicopathological correlation may help enhance discrimination of genetically related SATs from sporadic cases. These data have implications for clinical and dermatopathological training provision, the development of reporting standards, and genetic assessment of selected patients., (© 2021 British Association of Dermatologists.)

Pilomatrix carcinoma (PC) is a rare malignant variant of pilomatrixoma, a skin adnexal tumor originating from hair matrix cells. It is most often located in the head, neck region, upper back and upper extremities. PC has a locally aggressive behavior but metastasis only occur in 10% of cases. Mutations in CTNNB1, the encoding gene of beta-catenin, have been found in both pilomatrixoma and PC, but other molecular alterations are unknown. The authors present a case of PC in the clitoris, the third known reported case located on the external genitalia. The tumor followed an unusual clinical course with the development of multiple metastases. Next-generation sequencing analysis of the tumor identified, in addition to a characteristic CTNNB1 mutation, pathogenic mutations in PTEN, PIK3CA, and ARID1A, which could explain the aggressive course of the disease. The diagnostic criteria of PC and the differential diagnoses of this unusual tumor in the genital area are discussed., Competing Interests: The authors declare no conflict of interest., (Copyright © 2020 by the International Society of Gynecological Pathologists.)

Pilomatricoma, also known as calcifying epithelioma of Malherbe, is a common benign skin adnexal tumor with differentiation toward hair cortex cells, commonly seen in head and neck region of children. It is usually solitary. Herein, we present a rare case of pilomatricoma with extensive osseous metaplasia as a thigh swelling in an adult female, considered clinically to be a sebaceous cyst. Florid osseous metaplasia is extremely rare in cases of pilomatricoma. To date, fewer than 10 cases of pilomatricoma with extensive osseous metaplasia at different sites have been reported in the English literature., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Pilomatricoma, a benign skin appendage tumor, also known as calcifying epithelioma, consists of islands of epithelial cells histologically that contain anucleated cells in the center surrounded by basophilic cells and partial calcification. Sporadic pilomatricomas commonly have somatic mutations in the gene CTNNB1, but causative genes from germline and the underlying pathophysiology are unclear. In this study, we identified a germline missense variant of PLCD1 encoding PLCδ1, c.1186G>A (p.Glu396Lys), in a large Chinese family with autosomal dominant multiple pilomatricomas. Phospholipase C, a key enzyme playing critical roles in intracellular signal transduction, is essential for epidermal barrier integrity. The p.Glu396Lys variant increased the enzymatic activity of PLCδ1, leading to protein kinase C/protein kinase D/extracellular signal-regulated kinase1/2 pathway activation and TPRV6 channel closure, which not only resulted in excessive proliferation of keratinocytes in vitro and in vivo but also induced local accumulation of calcium in the pilomatricoma-like tumor that developed spontaneously in the skin of Plcd1 E396K/E396K mice. Our results implicate this p.Glu396Lys variant of PLCD1 from germline leading to gain-of-function of PLCδ1 as a causative genetic defect in familial multiple pilomatricomas., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

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., (© 2020 The Australasian College of Dermatologists.)

Pilomatrixoma is a benign subcutaneous tumour arising from the sebaceous glands. Mutation in the CTNNB1 gene is seen, suggesting beta-catenin misregulation may be the cause of pilomatrixoma. The preoperative diagnosis may be improved by the awareness of the fact that pilomatrixoma is a common and benign skin tumour of the head and neck region. It presents as a well-defined mass, which may be firm to hard in consistency, usually attached to the skin, but not to the underlying tissue. The colour of overlying skin appears a reddish-brown tinge, indicating that it could be a case of pilomatrixoma. Here, we report a case of pilomatrixoma of the cheek in a woman along with the CT findings and histopathological appearances. Dental surgeons should consider it as one of the differential diagnosis in superficial head and neck swelling with calcification., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Malignant pilomatricoma (MP) is a rare cancer of the hair matrix with only a few cases reported in literature. Given the rarity of this cancer and the lack of relevant genetic data, very little is known about the nature of the molecular pathophysiology except the involvement of the Catenin Beta 1 (CTNNB1)/Wnt/β-catenin signaling pathway in some cases., Materials and Methods: We describe the whole-exome genomic profiling of four samples from two patients: 1) an MP from patient I, 2) a coexisting benign pilomatricoma (BP) from patient I, 3) a BP from an age and location-matched control patient II, and 4) normal skin tissue from patient II., Results: We detected a pathogenic somatic missense mutation in fibroblast growth factor receptor 4 (FGFR4) (c.1162G>A, p. Gly388Arg) in MP and coexisting BP in patient I, whereas the control BP harbored the classical CTNNB1 mutant., Conclusion: This study, the first comparative analysis of benign and MP through whole-exome analysis, identified a novel oncogenic mutation in FGFR4., (Copyright© 2020, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

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.

Pilomatrixoma is a benign adnexal tumor very common in pediatric age and in young adults that derives from follicular matrix cells. Although clinically it usually presents as a subcutaneous nodule of bluish color less than 3cm in size, multiple clinicopathological variants have been described in the literature. Among these we can find the giant pilomatrixoma, a rare clinical variant that reaches a size greater than or equal to 4cm and can simulate the clinical presentation of a malignant neoplasm. We report a 59-year-old man with an exophytic and ulcerated nodule in the left parotid region that was removed with the suspected diagnosis of a cutaneous squamous cell carcinoma. Histopathological analysis showed a proliferation of basaloid cells with areas of transition to ghost cells, under granulation tissue, hemorrhage, and an ulcerated epidermis. Thus, the diagnosis of giant pilomatrixoma was made. We reviewed the literature and found a total of 53 articles that report a total of 71 cases of giant pilomatrixoma. It is important to recognize this clinical subtype of pilomatrixoma because, apart from the possibility of being clinically confused with malignant lesions, the clinicopathological differential diagnosis must be made with the proliferating pilomatrixoma and pilomatrixcarcinoma.

Context: Primary Ovarian insufficiency (POI) affects 1% of women aged <40 years and leads most often to definitive infertility with adverse health outcomes. Very recently, genes involved in deoxyribonucleic acid (DNA) repair have been shown to cause POI., Objective: To identify the cause of a familial POI in a consanguineous Turkish family., Design: Exome sequencing was performed in the proposita and her mother. Chromosomal breaks were studied in lymphoblastoid cell lines treated with mitomycin (MMC)., Setting and Patients: The proposita presented intrauterine and postnatal growth retardation, multiple pilomatricomas in childhood, and primary amenorrhea. She was treated with growth hormone (GH) from age 14 to 18 years., Results: We identified a novel nonsense variant in exon 9 of the minichromosome maintenance complex component 8 gene (MCM8) NM&#95;001281522.1: c0.925C > T/p.R309* yielding either a truncated protein or nonsense-mediated messenger ribonucleic acid decay.The variant was homozygous in the daughter and heterozygous in the mother. MMC induced DNA breaks and aberrant metaphases in the patient's lymphoblastoid cells. The mother's cells had intermediate but significantly higher chromosomal breaks compared with a control., Conclusion: We describe a novel phenotype of syndromic POI related to a novel truncating MCM8 variant. We show for the first time that spontaneous tumors (pilomatricomas) are associated with an MCM8 genetic defect, making the screening of this gene necessary before starting GH therapy in patients with POI with short stature, especially in a familial or consanguineous context. Appropriate familial monitoring in the long term is necessary, and fertility preservation should be considered in heterozygous siblings to avoid rapid follicular atresia., (© Endocrine Society 2020. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

We present a case report of the exceptionally rare pilomatrical carcinosarcoma in an even rarer pediatric age group, a 9-year-old female patient. The tumor showed biphasic pilomatrical carcinoma and malignant sarcomatous transformation. To date, the patient is healing well without signs of recurrence. Although limited clinical follow-up is available due to the recent diagnosis, this case may provide a rare look at the clinical outcome of this very rare tumor.