BACKGROUND: 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).
CONCLUSIONS: 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.

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.
OBJECTIVE: 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.
CONCLUSIONS: The study was retrospective, and the sample size was small.
CONCLUSIONS: 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.

To explore and compare the ultrasonic (US) features of pilomatricoma (PM) and epidermoid cyst (EC) in the differential diagnosis and improve the accuracy of US diagnosis of PM.
Three hundred and nine patients who underwent US examination before surgery with a histopathological diagnosis of PM or EC after surgery were analysed retrospectively. The patients were categorised into the training and validation sets according to the inspection times. Univariate analysis was undertaken on the US and clinical features of PM and statistically significant variables (p<0.05) were included in the multivariate logistic regression model to establish a diagnostic model.
The results demonstrated that the multivariate logistic regression model for PM was statistically significant (p<0.001). The risk factors included posterior echo attenuation and hypoechoic halos (odds ratio [OR] = 9.277, 10.254) and the protective factors included age, diameter thickness, and posterior echo enhancement (OR=0.936, 0.302, 0.156). The performance of the diagnostic model was tested using the training set (area under the receiver operating characteristic curve [AUC] = 0.974, 95% confidence interval [CI] = 0.955-0.994) and the validation set (AUC = 0.967, 95% CI = 0.926-1.000), which demonstrated good discriminant ability.
The diagnostic accuracy for PM was higher than that for EC when the nodule is characterised by posterior echo attenuation, hypoechoic halos, smaller thickness, and younger age. The US diagnostic model developed may be used to guide the diagnosis of PM.

Cutaneous adnexal tumors (CAT) are rare tumors originating from the adnexal epithelial parts of the skin. Due to its clinical and histopathological characteristics comparable with other diseases, clinicians and pathologists experience difficulties in its diagnosis.We aimed to reveal the clinical and histopathological characteristics of the retrospectively screened cases and to compare the prediagnoses and histopathological diagnoses of clinicians.
The data of the last 5 years were scanned and patients with histopathological diagnosis of CAT were included in the study.
A total of 65 patients, including 39 female and 26 male patients aged between 8 and 88, were included in the study. The female to male ratio was 1.5, and the mean age of the patients was 46.15 ± 21.8 years. The benign tumor rate was 95.4%, whereas the malignant tumor rate was 4.6%. 38.5% of the tumors were presenting sebaceous, 35.4% of them were presenting follicular, and 18.5% of them were presenting eccrine differentiation. It was most commonly seen in the head-neck region with a rate of 66.1%. When clinical and histopathological prediagnoses were compared, prediagnoses and histopathological diagnoses were compatible in 45% of the cases. Most frequently, it was the basal cell carcinoma, epidermal cyst, and sebaceous hyperplasia identified in preliminary diagnoses.
Cutaneous adnexal tumors are very important, as they can accompany different syndromes and may be malignant. Due to difficulties in its clinical diagnosis, histopathological examination must be performed from suspicious lesions for definitive diagnosis.

A pilomatrixoma is a benign skin tumor common in children, which develops from the matrix cells of hair follicles. It presents as a nodule or tumor of approximately 0.5-3 cm in size, with calcium-like consistency, faceted edges, and blue erythematous overlying skin. Sometimes, the skin may atrophy and look like a blister or even extrude calcium. Diagnosis is suspected based on the typical clinical presentation and supplementary imaging tests. The definite diagnosis is made according to histological findings. Surgical removal is the treatment of choice. Here we describe the epidemiological and clinical data, supplementary tests, and surgical techniques in relation to 149 pilomatrixomas resected in 137 patients treated at the Departments of Dermatology of two children\'s hospitals: Dr. Pedro de Elizalde and Prof. Dr. Juan P. Garrahan.
El pilomatrixoma es un tumor benigno cutáneo, de frecuente aparición en los niños, que se origina en las células de la matriz del folículo piloso. Se presenta como un nódulo o tumor, aproximadamente, de 0,5 a 3 cm de tamaño, de consistencia cálcica, de bordes facetados, con piel suprayacente eritematoazulada. En ocasiones, la piel puede atrofiarse, dar la apariencia de una ampolla e, incluso, extruir material cálcico. El diagnóstico se sospecha por la presentación clínica característica y los estudios de imágenes complementarios. El diagnóstico definitivo es por los hallazgos histológicos. La extirpación quirúrgica es el tratamiento de elección. Se presentan los datos epidemiológicos, clínicos, estudios complementarios y técnicas quirúrgicas empleadas de 149 pilomatrixomas resecados en 137 pacientes tratados en los Servicios de Dermatología de los hospitales de pediatría Dr. Pedro de Elizalde y Prof. Dr. Juan P. Garrahan.

Pilomatricoma is usually a single lesion. However, some patients present with more than one, a fact that has been reported in association with several systemic diseases. The aim of this analysis is to determine the prevalence of multiple pilomatricomas (MP) in our institution as well as to describe their clinical features and associated comorbidities. This is a retrospective analysis reviewing patients with a histological diagnosis of pilomatricoma registered in the database of the Pathology Department of our institution, from January 2005 to March 2017. One hundred ninety-five patients with histological criteria for pilomatricoma were registered. Fourteen (0.7%) of those patients suffered from MP. Among them, the most relevant findings were: 9 (64%) patients were women and 5 (36%) were men. The median age at diagnosis was 16 years. Seven (50%) had 2 pilomatricomas and 7 (50%) had more than 2. Two (14%) suffered from Steinert myotonic dystrophy (SMD). Regarding family background, 3 of them had relatives with pilomatricomas, one of them with pancreatic cancer, and another one with SMD. A total of 36 pilomatricomas were excised from those 14 patients with the following characteristics: The mean lesion size was 12 mm. The majority of the lesions (53%) were located on the head and neck. There was no recurrence or malignant transformation in any patient. Articles reporting on MP are scarce. We communicate 2 new familial MP without associated comorbidities. We would like to highlight that 2 of our patients with MP also developed SMD, an association previously reported. Thus, a thorough physical examination and inquiring about family history are of utmost importance for an early diagnosis of possible associated diseases.

Basal cell carcinoma (BCC) with matrical differentiation is a fairly rare neoplasm, with about 30 cases documented mainly as isolated case reports. We studied a series of this neoplasm, including cases with an atypical matrical component, a hitherto unreported feature. Lesions coded as BCC with matrical differentiation were reviewed; 22 cases were included. Immunohistochemical studies were performed using antibodies against BerEp4, β-catenin, and epithelial membrane antigen (EMA). Molecular genetic studies using Ion AmpliSeq Cancer Hotspot Panel v2 by massively parallel sequencing on Ion Torrent PGM were performed in 2 cases with an atypical matrical component (1 was previously subjected to microdissection to sample the matrical and BCC areas separately). There were 13 male and 9 female patients, ranging in age from 41 to 89 years. Microscopically, all lesions manifested at least 2 components, a BCC area (follicular germinative differentiation) and areas with matrical differentiation. A BCC component dominated in 14 cases, whereas a matrical component dominated in 4 cases. Matrical differentiation was recognized as matrical/supramatrical cells (n=21), shadow cells (n=21), bright red trichohyaline granules (n=18), and blue-gray corneocytes (n=18). In 2 cases, matrical areas manifested cytologic atypia, and a third case exhibited an infiltrative growth pattern, with the tumor metastasizing to a lymph node. BerEP4 labeled the follicular germinative cells, whereas it was markedly reduced or negative in matrical areas. The reverse pattern was seen with β-catenin. EMA was negative in BCC areas but stained a proportion of matrical/supramatrical cells. Genetic studies revealed mutations of the following genes: CTNNB1, KIT, CDKN2A, TP53, SMAD4, ERBB4, and PTCH1, with some differences between the matrical and BCC components. It is concluded that matrical differentiation in BCC in most cases occurs as multiple foci. Rare neoplasms manifest atypia in the matrical areas. Immunohistochemical analysis for BerEP4, EMA, and β-catenin can be helpful in limited biopsy specimens. From a molecular biological prospective, BCC and matrical components appear to share some of the gene mutations but have differences in others, but this observation must be validated in a large series.

Pilomatricoma is a common and benign skin tumor of childhood arising from the hair follicle matrix. It is an often misunderstood adnexal tumor, confused with other skin lesions. The most common sites of pilomatricome are the head and the neck. The aim of this study was to report a series of 22 cases with unusual forms collected in the dermatology department from January 2006 to May 2015. The study included 16 women and 6 men. The average age was 23.3 years (4- 80 years). Cervicofacial location was observed in 12 cases, 2 patients had multiple locations, a 4 year-old boy had frontotemporal location, a 14 year-old girl had face and forearm location and a 48 year-old patient had subungual location. Clinical features were typical in all cases, with subcutaneous nodules with a stony-hard consistency. All patients underwent excision of nodules under local anesthesia. Histological study supported a completely excised Malherbe\'s mummified tumor without malignancy. No patients relapsed. The originality of our study lies in the presence of exceptional locations in laterovertebral region, on limbs and in the subungual region and of unusual age of onset (80 year-old) as well as the presence of multiple tumor locations reported in 2 children.

For pilot or experimental employment programme results to apply beyond their test bed, researchers must select \'clusters\' (i.e. the job centres delivering the new intervention) that are reasonably representative of the whole territory. More specifically, this requirement must account for conditions that could artificially inflate the effect of a programme, such as the fluidity of the local labour market or the performance of the local job centre. Failure to achieve representativeness results in Cluster Sampling Bias (CSB). This paper makes three contributions to the literature. Theoretically, it approaches the notion of CSB as a human behaviour. It offers a comprehensive theory, whereby researchers with limited resources and conflicting priorities tend to oversample \'effect-enhancing\' clusters when piloting a new intervention. Methodologically, it advocates for a \'narrow and deep\' scope, as opposed to the \'wide and shallow\' scope, which has prevailed so far. The PILOT-2 dataset was developed to test this idea. Empirically, it provides evidence on the prevalence of CSB. In conditions similar to the PILOT-2 case study, investigators (1) do not sample clusters with a view to maximise generalisability; (2) do not oversample \'effect-enhancing\' clusters; (3) consistently oversample some clusters, including those with higher-than-average client caseloads; and (4) report their sampling decisions in an inconsistent and generally poor manner. In conclusion, although CSB is prevalent, it is still unclear whether it is intentional and meant to mislead stakeholders about the expected effect of the intervention or due to higher-level constraints or other considerations.

BACKGROUND: Myotonic dystrophy type 1 (MD1) is reported to be associated with internal malignancies. The association of myotonic dystrophy with cutaneous tumors is not fully understood.
OBJECTIVE: We sought to explore the total nevi count and the presence of atypical nevi, cutaneous melanoma, and other skin neoplasms in a representative cohort of patients with MD1 and to compare the findings with age- and sex-matched control subjects.
METHODS: In all, 90 patients with MD1 and 103 age- and sex-matched control subjects were assessed for cutaneous neoplasms by clinical skin and epiluminescence examination (dermoscopy). Where indicated, subsequent excisions were performed. In patients with MD1, leukocyte n(CTG) expansion was measured.
RESULTS: Patients with MD1 showed significantly higher numbers of nevi, dysplastic nevi, and melanomas despite a significantly greater proportion of the control subjects reporting sunburns. In addition, we found a significantly greater number of pilomatrixoma in patients with MD1.
CONCLUSIONS: Our study is limited by the fact that there is no agreed-upon standardized technique to assess for prior sun exposure. Further research in the association of cutaneous neoplasms and MD1 including vitamin D and molecular biological techniques are also recommended.
CONCLUSIONS: MD1 itself may predispose to development of skin tumors.