Sonography in pathologies of scalp and hair

Seeing beyond skin deep: High-resolution ultrasound in dermatology-A comprehensive review and future prospects

High-resolution ultrasound (HRUS), operating at frequencies of 20-25 MHz, is a non-invasive imaging tool that offers dermatologists the ability to visualize structures beneath the skin surface. The objective of this review is to present a comprehensive overview of HRUS applications, emphasising its utility in diagnosing, characterising and managing various dermatological conditions. We undertook a comprehensive literature review on the dermatological application of HRUS across Medline, Embase and Cochrane Library databases, while also incorporating our own clinical experience of over 16 years with the tool. In normal skin, the epidermis and dermis are hyperechoic, and the subcutaneous layer is hypoechoic. Basal cell carcinomas appear hypoechoic with irregular margins, while the presence of hyperechoic inclusion bodies suggests aggressive pathology. Squamous cell carcinomas pose challenges due to acoustic shadow artefacts from the thickened stratum corneum. Melanomas are homogenous hypoechoic lesions, with HRUS used to accurately predict Breslow thickness. HRUS provides dermatologists with a valuable adjunct to traditional clinical examination. Future advancement in image resolution and the standardisation of diagnostic parameters may further expand its utility.

How to Start on Dermatologic Ultrasound: Basic Anatomical Concepts, Guidelines, Technical Considerations, and Best Tips

Dermatologic ultrasound has grown exponentially during the last decades and has passed from the experimental phase to the routine daily practice in multiple countries. The performance of this imaging technique requires color Doppler ultrasound devices working with high-frequency probes, a trained operator on imaging and dermatologic conditions, and the performance of standardized protocols for obtaining the anatomical data properly. In this review, we analyze the ultrasonographic anatomy of the skin, hair, and nails, the technical requirements and considerations, the guidelines, and the recommended protocols, and provide the best tips for practicing this type of examination confidently.

Efficacy of type A botulinum toxin treatment for androgenetic alopecia using ultrasound combined with trichoscopy

OBJECTIVE

This study aimed to assess the efficacy of type A botulinum toxin treatment for androgenetic alopecia (AGA) using a combination of ultrasound and trichoscopy.

METHODS

Ninety patients with AGA who visited the Department of Dermatology at the Second Affiliated Hospital of Soochow University from September 2021 to December 2022 were prospectively selected. These patients met the diagnostic criteria outlined in the Chinese Guidelines for the Diagnosis and Treatment of Androgenetic Alopecia. The alopecia severity in the male patients ranged between grades 2 and 4 on the Norwood-Hamilton Scale. The patients were randomly assigned to receive injections of the same type of biological agent in a double-blind manner, with injection sites being the vertex or bilateral temporal-frontal hairline. In this study, the botulinum toxin group comprised 72 patients who received a biological agent with 100 units of type A botulinum toxin. The control group included 18 patients, and the biological agent administered to them contained 0 units of type A botulinum toxin. The patients were observed using 22-MHz ultrasound and trichoscopy before treatment, and 1 month and 3 months after treatment to compare the differences in various parameters at the injection sites. The ultrasound parameters included average follicle width, length, and count. The trichoscopy parameters were the number of hairs within a 1-cm2 area on the counting scale. No artificial interventions were performed at the injection sites, and all examination conditions were consistent.

RESULTS

The patients in the botulinum toxin group had wider and longer average follicle width and length at the vertex 1 month and 3 months after treatment (p < 0.05), and wider and longer average follicle width and length in the left frontal area 3 months after treatment (p < 0.05) compared with those in the control group. The average follicle width and length gradually increased after treatment in the botulinum toxin group (p < 0.05), but no statistically significant differences were found in the control group (p > 0.05). The patients in the botulinum toxin group exhibited greater average follicle lengths after treatment at the vertex compared with the left frontal area (p < 0.05). No statistically significant differences were found in follicle count (p > 0.05) or hair count (p > 0.05) between the botulinum toxin and control groups after injection treatment.

CONCLUSIONS

The follicle width and length are effective parameters for evaluating the efficacy of type A botulinum toxin treatment for AGA. Ultrasound revealed that the changes in follicles at the vertex occurred earlier than those in the left frontal area following treatment. Additionally, the changes in follicles were detected earlier than the changes in hair count using ultrasound. Ultrasound combined with trichoscopy provided more parameters for evaluating the efficacy of type A botulinum toxin treatment for AGA, resulting in a more comprehensive evaluation.

The role of imaging technologies in the diagnosis of hidradenitis suppurativa

Hidradenitis suppurativa is a chronic, inflammatory, recurrent, and debilitating disease of the hair follicle. It presents with painful, deep-seated, inflamed lesions, such as nodules, abscesses, sinus tracts, and fistulas, generally located in the main folds. Clinical severity assessment alone can be reductive; noninvasive skin imaging technologies, such as ultrasound, magnetic resonance imaging, medical infrared thermography, computed tomography, and positron emission tomography, provide subclinical anatomical and functional details. These instrumental techniques confirm the clinical suspect, thus allowing an earlier diagnosis and improving patients' clinical evaluation, staging, and management. Finally, they might be helpful for preoperative mapping. In this contribution, we provide an overview of the current knowledge about noninvasive skin imaging techniques with a particular focus on ultrasonography, which is widely used thanks to its precision, versatility, and availability.

Diagnosis and differential diagnosis of tertiary androgenetic alopecia with severe alopecia areata based on high-resolution MRI

BACKGROUND AND AIM

No previous study investigated the anatomical changes of the scalp and hair follicles between tertiary androgenetic alopecia and severe alopecia areata using high-resolution magnetic resonance imaging (HR-MRI). This study aimed to explore the value of HR-MRI in assessing alopecia.

MATERIALS AND METHODS

Forty-eight people were included in this study. The imaging indicators of the vertex and occipital scalp were recorded and compared. The logistic regression model was developed for the indicators that differed between tertiary androgenetic alopecia and severe alopecia areata. The receiver-operating characteristic (ROC) curve was used to assess the diagnostic efficacy of the model for tertiary androgenetic alopecia and severe alopecia areata.

RESULTS

At the vertex, the thickness of the subcutaneous tissue layer, follicle depth, relative follicle depth, total number of follicles within a 2-cm distance, and number of strands reaching the middle and upper third of the subcutaneous fat layer within a 2-cm distance were statistically different between patients with tertiary androgenetic alopecia, those with severe alopecia areata, and healthy volunteers (p < 0.05). The logistic regression model suggested that the subcutaneous tissue layer thickness was important in discriminating tertiary androgenetic alopecia from severe alopecia areata. The ROC curve showed that the area under the curve, sensitivity, specificity, and best cutoff values of the subcutaneous tissue layer were 0.886, 94.4%, 70%, and 4.31 mm, respectively.

CONCLUSIONS

HR-MRI can observe the changes in anatomical structures of the scalp and hair follicles in patients with alopecia. HR-MRI can be applied to the differential diagnosis of tertiary androgenetic alopecia and severe alopecia areata.

Non-Invasive Techniques for Evaluating Alopecia Areata

Alopecia areata (AA) is a disease affecting mostly young patients, being the second most prevalent cause of alopecia. For the assessment of AA patients, numerous non-invasive techniques are available. For diagnosing and treating AA, non-invasive hair follicle exploration is crucial. Trichoscopy, videodermoscopy, pull test, global scalp photography and scalp imaging techniques (reflectance confocal microscopy (RCM), multiphoton microscopy (MPM), and high-frequency ultrasonography (HF-USG) are non-invasive methods used to assess the hair loss. Short vellus hairs and yellow dots were the most commonly reported and sensitive trichoscopy signs of AA. Additionally, it was observed that AA activity was associated with black dots, micro-exclamation mark hairs and tapering hairs. A good prognosis of AA includes the transformation of vellus into terminal hairs. Reflectance confocal microscopy is a non-invasive imaging technique for in vivo evaluation of the skin and observation of cell morphology with a nearly histological resolution, which is helpful in diagnosis and management of AA. Additionally, MPM delivers information on hair follicles and scalp inflammation and can be utilized to assess hair growth while undergoing treatment. High-frequency ultrasonography allows distinguishing between hair cycle phases, which is undoubtedly important from the prognostic of AA. The current review aims to discuss the non-invasive methods of diagnosis of AA.

Assessing the accuracy of computed tomography in detecting bony invasion and thickness of squamous cell carcinoma of the scalp

OBJECTIVES

The aim of this study was to ascertain the accuracy of computed tomography (CT) in assessing the presence of bony involvement and thickness of squamous cell carcinoma (SCC) of the scalp.

METHODS

A single-centre retrospective chart review was carried out. Inclusion criteria were scalp SCC, CT between January 2008 and 2018, and the availability of a reference test. Reference tests were either histology, surgical notes or clinical notes. Tabular assessment of accuracy was performed and Student's t-test, Mann-Whitney U test and Fisher exact test were used in univariable analysis. Accuracy of thickness measurement was calculated using the limits of agreement method, and linear regression was used to examine trend.

RESULTS

Thirty-nine patients were included. Most patients were male (74.4%), white (97.4%), not immunosuppressed (66.6%) and had poorly differentiated tumours (33.3%). The most common tumour sites were the vertex (28.2%) and temporal region (23.1%). Sensitivity of CT in detecting presence or absence of bony invasion of scalp SCC was 76.9% (95% CI 46.2-94.9%) and specificity was 96.2% (95% CI 80.4-99.9%). Overall accuracy was 89.7% (95% CI 75.8-97.1%), positive predictive value was 90.1% (95% CI 58.7-99.8%) and negative predictive value was 89.3% (95% CI 71.8-97.7%). No significant differences were found comparing patients with an accurate or inaccurate CT scan. Thickness on CT was found to be consistent with histological thickness at the 95% confidence level.

CONCLUSIONS

CT is accurate at assessing the presence of bony involvement and thickness of scalp SCC. This study was limited somewhat by small sample size.

Ultra high-frequency ultrasound with seventy-MHz transducer in hair disorders: Development of a novel noninvasive diagnostic methodology

BACKGROUND

Ultra high-frequency ultrasound (uHFUS) is a recently developed diagnostic technology. Despite its potential usefulness, no study has assessed its advantage in diagnosis and evaluation of hair disorders in comparison with other diagnostic methods.

OBJECTIVES

To assess the practicability of uHFUS in diagnosing hair disorders and propose a diagnostic methodology.

METHODS

Ultrasonographic images of scalp and forehead from patients with hair disorders (n = 103) and healthy controls (n = 40) were obtained by uHFUS and analyzed by both descriptive and numerical parameters. Furthermore, the data were compared with trichoscopic and histopathological findings.

RESULTS

The pattern of inflammation and fibrosis, hair cycle abnormality, and the findings in subcutis were detected by uHFUS. Significant differences were noted in the numerical parameters associated with the number of hair shafts and follicles, hair diameters and their diversity, and dermal echogenicity in both cicatricial and non-cicatricial hair disorders. Findings in uHFUS were associated with those observed in trichoscopy and scalp biopsy but uHFUS was able to detect pathological findings associated with hair cycle, inflammation, fibrosis, and subcutaneous abnormalities, which are hardly assessable by trichoscopy.

CONCLUSION

The findings of this study highlighted usefulness of uHFUS in diagnosing hair disorders, while overcoming the weaknesses and limitations of other diagnostic tools.

High-frequency ultrasound in clinical dermatology: a review

Background

Ultrasound was first introduced in clinical dermatology in 1979. Since that time, ultrasound technology has continued to develop along with its popularity and utility.

Main text summary

Today, high-frequency ultrasound (HFUS), or ultrasound using a frequency of at least 10 megahertz (MHz), allows for high-resolution imaging of the skin from the stratum corneum to the deep fascia. This non-invasive and easy-to-interpret tool allows physicians to assess skin findings in real-time, enabling enhanced diagnostic, management, and surgical capabilities. In this review, we discuss how HFUS fits into the landscape of skin imaging. We provide a brief history of its introduction to dermatology, explain key principles of ultrasonography, and review its use in characterizing normal skin, common neoplasms of the skin, dermatologic diseases and cosmetic dermatology.

Conclusion

As frequency advancements in ultrasonography continue, the broad applications of this imaging modality will continue to grow. HFUS is a fast, safe and readily available tool that can aid in diagnosing, monitoring and treating dermatologic conditions by providing more objective assessment measures.

Overview of Ultrasound Imaging Applications in Dermatology

Complete visualization of lesions is critical for the accurate diagnosis and management of dermatological diseases. Currently, the most readily available technologies used by dermatologists include dermoscopy and photography. Nevertheless, ultrasound has emerged as a useful non-invasive modality in dermatology, which can be added to the clinical examination supporting an early and more accurate diagnosis. Moreover, there are significant technological advances in recent years, such as the development of handheld devices and ultra-high frequency probes that have expanded the integration of ultrasound into daily dermatology practice. In this article, we reviewed the most common applications of ultrasound in the field of dermatology.

European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) Position Statement on Dermatologic Ultrasound

Dermatologic ultrasound is a recent application of ultrasound for the evaluation of healthy skin and appendages and their diseases. Although the scientific literature regarding this application is still not sufficient for evidence-based guidelines, general recommendations issued by scientific societies are necessary. The EFSUMB (European Federation of Societies for Ultrasound in Medicine and Biology) steering committee for dermatologic ultrasound has developed a series of consensus position statements regarding the main fields of dermatologic ultrasound (technical requirement, normal skin and appendages, inflammatory skin diseases, tumoral skin diseases, aesthetic dermatology and practice-training requirements). This document is the foundation for future evidence-based recommendations and guidelines for dermatologic ultrasound practice.

Colour Doppler ultrasound study in patients with frontal fibrosing alopecia

BACKGROUND

The sonographic characteristics of frontal fibrosing alopecia have been scarcely studied. The aim of this study was to perform a colour Doppler ultrasound evaluation in frontal fibrosing alopecia.

MATERIALS AND METHODS

A cross-sectional study including 99 women with frontal fibrosing alopecia and 40 control subjects was performed using ultrasound equipment with a lineal 18 MHz probe. Three areas were evaluated per patient: the alopecic area (a), the hairline implantation area (b) and healthy scalp (c). The diameter (cm) and flow (m/s) of the two most significant vessels were recorded.

RESULTS

With regard to the hairline implantation area, patients presented higher vessel diameter (0.127 cm vs 0.103 cm, P = .03) and vessel flow (8.183 m/s vs 7.670 m/s, P = .05) than the control group. Vessel diameter was higher in the healthy scalp area in patients than in the control group (0.088 cm vs 0.078 cm, P = .03).

CONCLUSION

Patients presented higher vessel diameter and flow in the hairline implantation area compared to the control group.

Ultrasound Morphologic Features of Steatocystoma Multiplex With Clinical Correlation

The ultrasound features of 87 steatocytoma multiplex (SCM) lesions detected in 9 patients are reported. Steatocytoma multiplex is a hamartomatous condition derived from the pilosebaceous duct junction that generates multiple cutaneous cystic lesions. It appeared as clusters of well-defined hypoechoic nodules with mild posterior enhancement in 100% of cases, with both dermal and subcutaneous locations in 67%. No calcification foci were detected within or at the periphery of the lesions. Fifty-six percent of the cases showed signs of hypervascularity in the edge of the nodules, and 44% of the lesions were associated with another dermatologic condition, most frequent being hidradenitis suppurativa (75%), followed by vellus hair cysts (25%). Steatocytoma multiplex shows ultrasound features that allow discrimination from other common cutaneous entities.

High-frequency ultrasonography of the scalp - Comparison of ultrasound and trichoscopic images in healthy individuals

BACKGROUND

Hair loss is a common problem in dermatological patients. Its diagnosis is based on selected non-invasive and invasive tests. Searching for new diagnostic methods, especially non-invasive ones, aims to accelerate the correct diagnosis in the least invasive way possible. The aim of our study was to establish the characteristics of ultrasound images in healthy individuals and to compare them to selected trichoscopic parameters.

MATERIALS AND METHODS

Eighteen healthy adults (10 women and 8 men) underwent trichoscopy and high-frequency ultrasound (HF-USG) with 20 MHz DermaScan transducer on the parietal region of the scalp. Selected parameters were compared in relation to sex and the research method used.

RESULTS

HF-USG of the parietal area in all examined patients revealed hyperechogenic entrance echo and less echogenic layer corresponding to the dermis with well-defined hypoechoic follicular structures (FS). The number of hair units in trichoscopy and the number of FS in HF-USG did not differ significantly, while the differences in the studied distances between structures were statistically significant. The width of FS in HF-USG was significantly higher than hair shafts thickness in trichoscopy.

CONCLUSIONS

HF-USG (20MHz) due to the possibility of visualization of FS can be a valuable complement to the range of non-invasive diagnostic procedures used in evaluation of the scalp.

MR Imaging of Hair and Scalp for the Evaluation of Androgenetic Alopecia

Purpose:

Although androgenetic alopecia (AGA) is a common cause of hair loss, little is known regarding the magnetic resonance imaging (MRI) of the AGA or scalp. This study aimed to analyze whether MRI for hair and scalp (MRH) can evaluate anatomical changes in the scalp caused by AGA.

Methods:

Twenty-seven volunteers were graded for the severity of AGA using the Hamilton–Norwood Scale (HNS), commonly used classification system. All subjects underwent MRH; two radiologists independently analyzed the images. As a quantitative measurement, the number of hair follicles was analyzed and compared with the HNS. As a qualitative analysis, each MRH scan was visually graded in terms of the severity of alopecia, using a 4-point MR severity score. The scores were compared with the HNS.

Results:

The volunteers were divided into two groups of 12 and 15 males without and with AGA at their vertex, respectively. Inter-observer agreements for the hair count and the MR severity score were excellent. The mean hair count on MRI in the normal group was significantly higher than that in the AGA group (P < 10⁻⁴). The MR severity score in the AGA group was significantly more severe than that in the control group (P < 10⁻⁴). In terms of the presence or absence of thinning hair, the MR severity score was consistent with the HNS determined by a plastic surgeon in 96% of cases. MR severity scores of clinically moderate AGA cases were significantly lower than those of severe cases (P = 0.022).

Conclusion:

MRH could depict scalp anatomy showing a clear difference between AGA and normal scalps, in both hair count and subjective visual assessment. The MR severity score was in good agreement with the clinical stages by HNS. The results support the potential of MRH as a promising imaging technique for analyzing healthy and pathological scalps.

Seventy-MHz Ultrasound Detection of Early Signs Linked to the Severity, Patterns of Keratin Fragmentation, and Mechanisms of Generation of Collections and Tunnels in Hidradenitis Suppurativa

OBJECTIVES

To test the capability of 70-MHz ultrasound for detecting initial ultrasound signs of hidradenitis suppurativa (HS) linked to severity.

METHODS

A cross-sectional study of the ultrasound images of patients with HS was conducted and compared with a healthy control group. Detection and identification of early subclinical ultrasound signs in the lesional and perilesional areas of the HS cases in comparison with the control group were performed. Statistical analyses included mean, dispersion measures, the Kruskal-Wallis test, and bivariate and multivariate ordered logistic regression studies. Significance was assessed at P < .05.

RESULTS

A total of 139 patients with HS met the criteria and showed abnormalities of the hair follicles such as a curved shape, ballooning, and protrusion into pseudocysts, collections, or tunnels (donor of keratin sign). Significant increases in the sizes of the hair follicles and hair shafts were found in HS cases. The following ultrasound signs were significantly linked to severity: a connecting band between the base of adjacent hair follicles (bridge sign), a fragment of the hair shaft extruding through a dilated hair follicle (sword sign), and retained cylindrical fragments of keratin in the dermis. Two patterns of fragmentation of the keratin were detected: multifragment and cylindrical.

CONCLUSIONS

Ultrasound can detect early HS signs that are significantly linked to severity and 2 types of fragmentation of the keratin, which could support the generation and perpetuation of the fluid collections and tunnels. These ultrasound signs can help prompt diagnosis and management, the development and testing of medications, and the measure of treatment outcomes in HS.

A bump: what to do next? Ultrasound imaging of superficial soft-tissue palpable lesions

Soft-tissue palpable lesions are common in clinical practice, and ultrasound (US) represents the first imaging option in the evaluation of a patient with a soft-tissue swelling. A full and systematic US assessment is necessary, however. This includes grayscale, color- and power-Doppler, spectral-Doppler, and possibly elastography facilities, as well as a trained operator. Several lesions showing characteristic US features can be diagnosed confidently, without any further work-up, and the high spatial resolution of ultrasound in the superficial layers can be a powerful tool to discriminate their etiologies. Second-level options, to be reserved for indeterminate cases or those suspected malignant at initial ultrasound, include magnetic resonance imaging, percutaneous fine-needle aspiration or biopsy, and surgical-excision biopsy. In this article, we discuss the proper US approach for addressing superficial soft-tissue lesions.

Images in Scalp Ultrasound Before and After Hair Transplant in Frontal Fibrosing Alopecia

ABSTRACT

Primary cicatricial alopecias are inflammatory scalp conditions that may lead to permanent hair loss and severe alopecia. Frontal fibrosing alopecia is one of the most frequent etiologies of primary cicatricial alopecias. Hair transplant could be a therapeutic option.High-resolution ultrasound (US) is an imaging technique useful for evaluating scalp with adequate differentiation of the skin layers. Also, hair follicles are visualized.The objectives are present presurgical and posttransplant scalp US studies on hair transplant.Frontal fibrosing alopecia is a chronic entity that can progress to extensive irreversible alopecia. Hair transplant is a surgical option. On US, the hair follicles are visualized as thin hypoechoic lines. With Doppler color imaging, it is possible to evaluate vascularization. In this experience, we can observe the follicles of the compromised area before and after the hair transplant and the depth of the implanted follicles.In conclusion, US impresses as a promissory technique for the imaging of hair transplant. More experience is necessary for a better approach of these findings.

Ultrasound Characteristics of the Hair Follicles and Tracts, Sebaceous Glands, Montgomery Glands, Apocrine Glands, and Arrector Pili Muscles

OBJECTIVES

To explore the capability of very high-frequency ultrasound (US; 50-71 MHz) to detect the normal morphologic characteristics of the hair follicles and tracts, sebaceous glands, Montgomery glands, apocrine glands, and arrector pili muscles.

METHODS

A retrospective study, approved by the Institutional Review Board, evaluated the normal US morphologic characteristics of the hair and adnexal structures in a database of very high-frequency US images extracted from the perilesional or contralateral healthy skin of 1117 consecutive patients who underwent US examinations for localized lesions of the skin and 10 healthy individuals from December 2017 to June 2018. These images were matched with their counterparts from the database of normal histologic images according to the corporal region. The Cohen concordance test and regional mean diameters of the hair follicles and adnexal structures were analyzed.

RESULTS

The normal hair follicles and tracts, sebaceous glands, Montgomery glands, apocrine glands, and arrector pili muscles were observed on US images and matched their histological counterparts in all the corporal regions. There was significant US concordance (κ = 0.82; P = .0001) among observers. Regional mean diameters (millimeters) of the hair follicles, sebaceous glands, and apocrine glands are provided.

CONCLUSIONS

The hair follicles and tracts, sebaceous glands, Montgomery glands, apocrine glands, and arrector pili muscles are detectable with very high-frequency US, including some regional and anatomic variants. Knowledge of their normal US appearances is a requisite for detecting subclinical changes, understanding the physiopathologic characteristics, and supporting the early diagnosis and management of common dermatologic diseases.

Trichilemmal Cyst: Clinical and Sonographic Features

OBJECTIVES

In this study, we retrospectively reviewed the clinical and sonographic features of patients with trichilemmal cysts.

METHODS

Sonographic findings of 54 cases of trichilemmal cysts were retrospectively analyzed from 50 patients, including 4 cases of proliferating trichilemmal cysts. Associated factors of internal calcification-positive cases were also evaluated.

RESULTS

The mean age of the 50 patients was 43.4 years (range, 15-80 years) and the female-to-male ratio was 1.3. Overall, 68% of the trichilemmal cysts in the 54 lesions were located in the scalp, and 15% were located in the extremities. All 54 lesions were preoperatively examined by sonography and showed well-defined, oval-shaped structures located in subcutaneous soft tissues close to the dermis. Of the 54 lesions, 72% were hypoechoic masses, 89% were heterogeneous, and 65% had internal calcification. Among the internal calcification-positive cases, the mean age of the patients was 43.4 years, and the female-to-male ratio was 0.6. Of these lesions, 83% were located in the scalp. We did not find any significant association between calcification, age, or sex (P = .993 and P = .99); however, lesions present in the scalp were significantly associated with internal calcification (P = .005). 81% of the 54 lesions displayed posterior enhancement. but the color Doppler sonography of all lesions revealed no vascularization.

CONCLUSIONS

Trichilemmal cysts should be considered to diagnose of well-defined, hypoechoic lesions with internal calcification and posterior sound enhancement in the subcutaneous soft tissues of the scalp or extremities upon sonography.

Imaging sonographic findings of in a case of proliferating trichilemmal tumor of a finger: A case report

Proliferating trichilemmal tumor (PTT) is a rare tumor that originates from the outer root sheath of a hair follicle. About 90% of PTTs occur on the scalp. The sonographic findings of PTT in the subungual region have not been reported previously. In our case, sonography showed a heterogeneous mass containing echogenic foci with no detectable intratumoral vascularity. These echogenic foci probably represent keratin and cholesterol. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 46:215-217, 2018.

Alopecic and aseptic nodule of the scalp in a girl

Alopecic and aseptic nodule of the scalp is a rare entity characterized by the presence of nodules or cysts with sterile punctured material and negative cultures accompanied by nonscarring alopecia in the scalp of young men. We describe a case in which an 11-year-old girl presented with a nodular, fluctuant, round lesion on the vertex with localized alopecia. High-resolution ultrasound showed a hypoechoic lesion with increased flow on Doppler imaging and culture of the citrine-yellowish material obtained by puncture was negative. The patient showed complete clinical response to treatment with topical indomethacin.

Sonography of Dermatologic Emergencies

Dermatologic conditions may be the subjects of potential emergency consultations, and the knowledge of their sonographic appearance can facilitate an early diagnosis and management. In this pictorial essay, the sonographic dermatologic anatomy, technique, and conditions that can be supported by a prompt sonographic diagnosis are reviewed. The sonographic signs that may help diagnose these entities are discussed with a practical approach.

High frequency ultrasound with color Doppler in dermatology

Ultrasonography is a method of imaging that classically is used in dermatology to study changes in the hypoderma, as nodules and infectious and inflammatory processes. The introduction of high frequency and resolution equipments enabled the observation of superficial structures, allowing differentiation between skin layers and providing details for the analysis of the skin and its appendages. This paper aims to review the basic principles of high frequency ultrasound and its applications in different areas of dermatology.

Dissecting Cellulitis of the Scalp Early Diagnosed by Color Doppler Ultrasound

Dissecting cellulitis of the scalp (DC) is a chronic inflammatory condition of the scalp that ultimately leads to scarring alopecia. A healthy 19-year-old male presented with a solitary, soft, alopecic nodule that had appeared 1 year before. A color Doppler ultrasound examination showed a hypodermal anechoic fluid collection in the left parietotemporal region of the scalp, connected to the base of widened hair follicles, and presented inner echoes suggestive of debris, as well as several fragments of hair tracts. A diagnosis of DC was made and an epidermal or trichilemmal cyst was ruled out. This case shows the importance of color Doppler ultrasound for supporting the diagnosis at an early stage or with an unusual presentation of DC.

Hair follicle characteristics as early marker of Type 2 Diabetes

Type 2 Diabetes mellitus (DM2) includes a continuum of metabolic disorders characterized by hyperglycemia that causes several chronic long-term complications such as coronary artery disease, peripheral arterial disease, nephropathy, and neuropathy. The hair follicle could reveal signs of early vascular impairment, yet its relationship to early metabolic injuries has been largely ignored. We propose that in earlier stages of the continuum of DM2-related metabolic disorders, a group of susceptible patients who do not yet meet the diagnostic criteria to be considered as persons with DM2 may present chronic vascular impairment and end organ damage, including hair follicle damage, which can be evaluated to identify an early risk marker. This hypothesis is based in the association found between insulin resistance and alopecia in non-diabetic persons, and the hair loss on the lower limbs as a manifestation of long-term peripheral arterial disease among subjects with DM2. In order to test this hypothesis, studies are required to evaluate if hair follicle characteristics are related to and can predict hyperglycemic complications, and if they do so, which feature of the hair follicle, such as hair growth, best characterizes such DM2-related conditions. If this hypothesis were proven to be true, significant advances towards a personalized approach for early prevention strategies and management of DM2 would be made. By focusing on the hair follicles, early stages of metabolic-related organ damage could be identified using non-invasive low-cost techniques. In so doing, this approach could provide early identification of DM2-susceptible individuals and lead to the early initiation of adequate primary prevention strategies to reduce or avoid the onset of large internal organ damage.

Imaging of Hidradenitis Suppurativa

Hidradenitis suppurativa is a complex disease of chronic evolution and difficult management. Imaging, particularly color Doppler ultrasound, has demonstrated a wide range of subclinical anatomic abnormalities, allowing modification of the clinical assessment of severity of the disease and therefore management of patients. Sonography supports early and more precise diagnosis and staging by providing critical objective information in real time. The richness of these data can also support assessment of the pathogenesis of the disease, allow monitoring of patients, and contribute to clinical trials. MRI can support the diagnosis of extensive anogenital and deep lesions.

Ultrasound Diagnosis and Staging in Pediatric Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) can affect children, and ultrasound has been proven to be useful in diagnosis and staging. The sonographic characteristics of HS in children have not been reported. We studied color Doppler ultrasound images of children (≤15 years old; n = 12) with clinically and sonographically positive criteria for HS. Sonographic scoring of hidradenitis suppurativa (SOS-HS) was used to stage the cases sonographically. Subclinical pseudocysts were found in 92% of the cases, fluid collections in 83%, and fistulous tracts in 58%. Retained hair tracts in the fluid collections and fistulous tracts were present in 100% of patients; 67% of cases were SOS-HS stage II. In 92% of cases, management was modified after the ultrasound examination. In conclusion, ultrasound can be a reliable and safe imaging tool to support diagnosis and staging and may help in the noninvasive monitoring of treatment in children.

Study of the skin anatomy with high-frequency (22 MHz) ultrasonography and histological correlation

The present essay is aimed at getting the radiologist familiar with the basic histological skin structure, allowing for a better correlation with sonographic findings. A high-frequency (22 MHz) ultrasonography apparatus was utilized in the present study. The histological analysis was performed after the skin specimens fixation with formalin, inclusion in paraffin blocks and subsequent staining with hematoxylin-eosin. The authors present a literature review showing the relationship between sonographic and histological findings in normal cutaneous tissue, and discuss the technique for a better performance of the sonographic scan. High-frequency ultrasonography is an excellent tool for the diagnosis of different skin conditions. However, as this method is operator-dependent, it is crucial to understand the normal skin structure as well as the correlation between histological and sonographic findings.

Multidimensional Ultrasound and Computed Tomography Imaging Support in Bleeding Plexiform Neurofibromatosis of the Scalp: A Case Report and Literature Review

Active bleeding in plexiform neurofibromatosis can be a life-threatening complication in neurofibromatosis type 1 (NF1). The prompt imaging support of 2D-3D ultrasound (US) and computed tomography (CT) during the active hemorrhage phase of cutaneous neurofibromas has not been previously reported. We report a case with NF1 who experienced a sudden swelling in the parieto-temporal region that corresponded to a massive and active hemorrhage within a plexiform neurofibroma. The US and CT imaging characteristics of this bleeding tumor are shown. Active hemorrhage in a plexiform neurofibroma of the scalp appeared in US as a heterogeneous hypodermal mass. CT demonstrated a fully hyperdense soft tissue mass. These characteristics differ from the non-complicated or old hemorrhagic imaging appearances of scalp plexiform neurofibromas and encourage prompt surgical treatment. This case report demonstrates the usefulness of imaging support in the early diagnosis of this hemorrhagic complication of NF1 in the scalp and also stimulates multispecialty management.

Hair morphology in androgenetic alopecia: sonographic and electron microscopic studies

OBJECTIVES

To assess hair morphology in androgenetic alopecia on sonography and electron microscopy.

METHODS

A prospective study was performed in 33 patients with androgenetic alopecia and 10 unaffected control participants. In vivo sonography of the hair follicles of the scalp and in vitro sonography and electron microscopy of the hair shafts were performed according to a standardized protocol that included analysis of the right frontal and occipital regions. The upper frequency limit of the ultrasound probes ranged between 15 and 18 MHz.

RESULTS

Scalp hair follicles and hair shafts were recognizable on sonography in all cases. Hair follicles in alopecia cases had significantly lower depths (P < .05). The hair shafts in alopecia also had a different distribution of their laminar pattern on in vitro sonography, with a greater presence of mixed (trilaminar and bilaminar) and solely bilaminar tracts in comparison with the controls (mostly trilaminar). On electron microscopy, the alopecia hair tracts showed irregularities and commonly a "melted candle" appearance of the cuticle.

CONCLUSIONS

Sonography and electron microscopy uncover distinct abnormalities in the morphology of hair in androgenetic alopecia, which may potentially support the diagnosis and management of this common condition.

Ultrasound skin imaging

The interaction of high-frequency ultrasound waves with the skin provides the basis for noninvasive, fast, and accessible diagnostic imaging. This tool is increasingly used in skin cancer and inflammatory conditions as well as in cosmetic dermatology. This article reviews the basic principles of skin ultrasound and its applications in the different areas of dermatology.