Abstract Melanonychia is the change in the coloration of the nail plate resulting from the deposition of melanin. Among its causes are melanocytic hyperplasia, melanocytic activation and nail melanoma. Subungual follicular inclusions are histological findings of unknown etiology, possibly related to trauma. We present three cases of melanonychia of different etiologies with subungual follicular inclusions, an association that has not been well described and with an indefinite pathogenesis.

Abstract: Atrophoderma of Pasini and Pierini is a skin disorder affecting dermal collagen and is clinically characterized by well-defined plaques of depressed skin. Histopathological changes are subtle, and in most cases, the diagnosis requires a comparative study with healthy skin from the same anatomical site. High frequency ultrasound is a useful imaging method for diagnosis of atrophic skin changes. A case is presented in which ultrasound can support the clinical and the histopathological diagnosis of atrophoderma of Pasini and Pierini.

Abstract: 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.

ResumoO objetivo deste trabalho é familiarizar o radiologista com a estrutura histológica cutânea, o que torna possível uma melhor correlação dos achados ultrassonográficos da pele. Para o exame radiológico foi utilizado aparelho de ultrassom de alta frequência (22 MHz). O exame histológico foi realizado após fixação do material em formol, inclusão em parafina e coloração com hematoxilina-eosina. Os autores fazem uma revisão da literatura, demonstram a relação dos achados ultrassonográficos e histológicos do tecido cutâneo normal e discutem a técnica para o melhor aproveitamento do exame ultrassonográfico da pele. O ultrassom de alta frequência representa uma excelente ferramenta no diagnóstico das diferentes alterações cutâneas. Como o método é operador-dependente, é crucial o perfeito entendimento da pele normal e sua equivalência histológica/ultrassonográfica.

AbstractThe 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.

The recent development of high-frequency ultrasound, associated with the improved sensitivity in color Doppler, enabled the identification of various skin structures and layers. In basal cell carcinoma, the 22 MHz frequency ultrasound permits the delimitation of tumor margins, while color Doppler, determines its vascularization. We present two cases in which the association of both exams allowed an in vivo analysis of the tumor's morphology, size, thickness and vascularization, thus contributing to a better pre-operative evaluation.