Characteristics and onset of presentation of pediatric stiff skin syndrome: A retrospective cohort study of 11 patients in a tertiary care center

Background/Objective: Stiff skin syndrome (SSS) is a rare disorder characterized by "rock hard" indurated skin affecting different body parts. The localized variant poses a diagnostic challenge, as it is frequently mistaken for other inflammatory connective tissue disorders. The aim of this study is to provide insightful clinical, radiologic and diagnostic data that might prove useful for the evaluation, management and treatment of pediatric patients with segmental SS.Methods: This single-center cohort study included patients <= 18 years diagnosed with localized SSS from 1988 to 2021 in a quaternary pediatric healthcare center in Toronto, Canada. Data included demographics, clinical, histopathologic and radiologic features, treatments, and clinical course. Data were summarized with descriptive statistics (mean, standard deviation, medians, interquartile ranges [IQRs]) and frequencies.Results: A total of 11 patients were included. The sclerotic changes were measured clinically and radiologically, by a total of 16 imaging studies: 13 magnetic resonance imaging (MRI) and 3 ultrasound. MRI readings showed abnormal high signal intensity of the affected tissue correlating with the anatomical site of involvement in all cases, specifically, in the shoulder/pelvic girdle with limb extension. Shear wave ultrasound elastography (SWE) demonstrated higher values within the dermis compared to the control site.Conclusion: The presence of segmental sclerotic changes that affects the pelvic/shoulder girdle with extension to the extremities, in the absence of inflammation on biopsy and abnormal signaling intensity on imaging is suggestive of SSS. Skin SWE is a feasible, noninvasive, and objective instrument to evaluate and monitor sclerotic changes overtime, it could be potentially extrapolated to other pediatric skin sclerotic conditions.