Abstract Background Tuberous sclerosis complex (TSC) is a multisystem neurocutaneous syndrome with variable phenotypes. Recent updates of TSC diagnostic criteria reaffirmed the defined genetic diagnostic criterion as the finding of a pathogenic DNA alteration in either TSC1 or TSC2 genes. It also slightly modified definite clinical diagnostic criteria. TSC-associated skin lesions in infancy are important clinical signs to select individuals with possible TSC for a closer clinical follow-up and genetic testing. Objective To raise awareness of the updated TSC diagnosis criteria; to assess the frequency of skin lesions in TSC patients as well as the first dermatological presentation; and to associate the findings with either TSC1 or TSC2 mutations. Methods Observational cross-sectional study. Clinical and genetic data were retrospectively collected from 37 TSC patients from a Brazilian University Hospital. Patients with skin signs were examined and prospectively assessed for 12 months. Results The earliest cutaneous lesions were hypomelanotic macules, which together with angiofibromas were the most frequent dermatological lesions. The total pathogenic DNA alteration ratio between TSC2 and TSC1 genes was 8:1. The frequency of a TSC2 pathogenic variant was 10-fold greater in the presence of ungual fibromas. Study limitations Small sample and a limited number of patients with TSC1 pathogenic variants. Conclusion Clinicians should be knowledgeable about TSC updated diagnostic criteria. Patients need to be followed up by a multidisciplinary team and treated accordingly. Early detection of cutaneous lesions is important for TSC diagnosis. A significant association between TSC2 gene pathogenic alterations and ungual fibromas is described. (TSC phenotypes TSCassociated associated followup follow testing presentation mutations crosssectional cross sectional study 3 Hospital 1 months macules 81. 81 8 1. 8:1 10fold fold 10 variants accordingly described 8:

Abstract Background Histopathology can be crucial for diagnosis of inflammatory nail diseases. Longitudinal excision and punch biopsies are the most used techniques to obtain the tissue sample. However, there is a low clinical-histopathological correlation, besides the risk of nail dystrophy. Tangential excision biopsy (TB) is a well-established technique for the investigation of longitudinal melanonychia. TB could also be used to evaluate diseases in which histopathological changes are superficial, as in psoriasis. Objective To study the value of TB in the histopathological diagnosis of nail psoriasis. Methods This is a prospective and descriptive study of the clinical-histopathological findings of samples from the nail bed or matrix and nail plate of 13 patients with clinical suspicion of nail psoriasis. Biopsies were obtained through partial nail avulsion and TB. Results In nine patients, the hypothesis of psoriasis was confirmed by histopathology; in one, the criteria for diagnosing nail lichen planus were fulfilled. The tissue sample of only one patient did not reach the dermal papillae, and, in four of 13 patients, the adventitial dermis was not sampled. No patient developed onychodystrophy after the procedure. Study limitations In three patients, the clinical and, consequently, histopathological nail changes were subtle. Also, in one patient’s TB didn’t sample the dermal papillae. Conclusions TB is a good option to assist in the histopathological diagnosis of nail psoriasis, especially when appropriate clinical elements are combined. Using this technique, larger and thinner samples, short postoperative recovery time, and low risk of onychodystrophy are obtained. However clinicalhistopathological correlation dystrophy (TB wellestablished well established melanonychia superficial 1 histopathology fulfilled papillae sampled procedure consequently subtle Also s didnt didn t combined time