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Introduction: Pilomatrixomas are benign neoplasms derived from hair follicle matrix cells. They are among the most common soft tissue head and neck tumors of childhood. Pilomatrixomas are typically isolated, slow-growing, firm, nontender masses that are adherent to the epidermis but mobile in the subcutaneous plane. This clinical presentation is so characteristic that many experienced surgeons will excise suspected pilomatrixomas without prior imaging. We reviewed the results of this approach to determine whether physical examination alone differentiates pilomatrixomas from other similar soft tissue lesions of the pediatric head and neck. Methods: Computerized review of all pilomatrixomas over a 20-year period in a single academic pediatric otolaryngology practice. Results: 18 patients presented to our pediatric otolaryngology practice between 2001 and 2021 with historical and physical findings consistent with pilomatrixoma. Of the 18 patients, 7 were male and 11 were female. Ages ranged from 1.5 to 14 years, with a mean of 7.5 years. Most of the lesions (12) were located in the head and face, while the rest (6) were found in the neck. All patients were treated with complete surgical excision. Pathology confirmed pilomatrixoma in 15 patients. The remaining 3 children were found to have an epidermal inclusion cyst, a ruptured trichilemmal cyst, and a giant molluscum contagiosum lesion, respectively. One additional patient presented with a small lesion of the auricular helix that was thought to be a dermoid cyst, but proved to be a pilomatrixoma on histologic examination. Discussion: As pilomatrixomas are common and have a very characteristic presentation, surgical excision without prior diagnostic imaging will lead to correct treatment in the majority of cases. High resolution ultrasonography can help to confirm the diagnosis preoperatively, but is not definitive in large case series. Most of the cystic lesions that imitate pilomatrixoma will ultimately require surgical excision., 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.

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., (© 2024 The Authors. Skin Research and Technology published by John Wiley & Sons Ltd.)

Aim: 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., Materials and Methods: 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., Results: 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., Conclusions: 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., (Copyright © 2023 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Objectives: To determine whether ultrasound (US) could distinguish a trichilemmal cyst from a pilomatricoma preoperatively., Methods: Ultrasound images of 61 pathologically proven trichilemmal cysts and 90 pathologically proven pilomatricomas were analyzed retrospectively. Two radiologists evaluated several US features. The sensitivity, specificity, Youden index, and predictive values of statistically significant US features were assessed. Parallel combined tests, serial combined tests, or both were performed to identify US features with high statistical significance., Results: Results from individual US features were not satisfactory; however, serial combined tests that included absence of complete internal echogenic foci, absence of a hypoechoic rim, absence of peritumoral hyperechogenicity, and absence of vascularity showed higher diagnostic utility. The sensitivity, specificity, Youden index, positive predictive value, and negative predictive value for correctly identifying a trichilemmal cyst were 74%, 88%, 0.62, 80%, and 83%, respectively. If 1 of these 4 US features was not a match for a trichilemmal cyst, pilomatricoma was considered., Conclusions: It may be possible to distinguish trichilemmal cysts from pilomatricomas preoperatively using US. A combined test is superior to using any individual US feature., (© 2020 by the American Institute of Ultrasound in Medicine.)

Background: Ultrasonography (US) has recently proved to be useful in diagnostic dermatology. It is convenient to use, completely safe, and provides valuable information., Objective: This study was performed to compare the diagnostic accuracy of US with that of clinical diagnosis in patients with benign subcutaneous lesions., Methods: We retrospectively examined data for 100 patients with benign subcutaneous lesions who were diagnosed with US and either biopsy or surgery at Seoul National University Boramae Hospital between January 2010 and May 2013., Results: Ultrasonography significantly increased the diagnostic yield of benign subcuta-neous lesions (after physical examination [PE], 52.0%; after US, 82.0%; P < 0.005). Rates of sensitivity and specificity for the diagnosis of lipoma were 61.5 and 92.0%, respectively, after PE, and 100 and 100%, respectively, after US. Rates of sensitivity and specificity for the diagnosis of epidermal cysts were 69.4 and 78.4%, respectively, after PE, and 91.8 and 92.2%, respectively, after US. Additionally, rates of sensitivity and specificity for pilomatrixoma were 12.5 and 98.9%, respectively, after PE, and 75.0 and 100%, respectively, after US. Although the accuracy of diagnosis of vascular anomalies and nerve sheath tumors was increased after US, the difference was not significant (vascular anomalies: 40.0% after PE and 80.0% after US; nerve sheath tumors: 28.6% after PE and 42.9% after US)., Conclusions: This study suggests that US is a simple and reliable tool that can aid the diagnosis of benign subcutaneous lesions., (© 2015 The International Society of Dermatology.)

Objective: Color Doppler sonography is used to distinguish malignant from benign subcutaneous nodules because many malignant tumors show an increased number of vessels. But benign lesions, such as inflammatory epidermal cysts, pilomatricomas, palmoplantar fibromatoses show vascular flow signals. We analyze diagnostic factors for subcutaneous nodules on the basis of ultrasonographic appearance including color Doppler sonography., Methods: We evaluated with sonography 79 subcutaneous nodules in histopathologically proven cases., Results and Discussion: The diagnostic findings for 28 epidermal cysts were increased posterior echo(sensitivity 77%, specificity 90%). Vascular flow signals were seen in 7 cases(25%). The signals were seen from periphery to adjacent zone of the mass. They were accompanied by inflammatory granulation tissues histologically. The percentage of blood flow may be related to the percentage of "ruptured" epidermal cysts. Pilomatricomas (n = 9) had internal echogenic foci or Doppler flow signals, and no posterior enhancement (sensitivity 89%, specificity 78%). Seven pilomatricomas showed Doppler flow signals in the mass. The percentage of flow signals is explained by the degree of internal echogenic foci because remarkable calcium deposits producing posterior acoustic shadowing prevent us from flow signals. Palmoplantar fibromatoses (n = 5) were ill-defined margins and showed internal vascularity with no posterior enhancement (sensitivity 80%, specificity 94%)., Conclusion: More benign lesions showed vascular flow signals than reported previously. We have to diagnose subcutaneous nodules referring to not only color Doppler but also gray scale sonography.