Evaluating skin biopsy findings in fibromyalgia: a systematic review

Fibromyalgia syndrome (FMS) is a condition characterized by widespread musculoskeletal pain, often involving a neuropathic component. While pathophysiology remains vague, increasing evidence suggests that small fiber pathology (SFP) may be present in a significant subset of patients, indicating a peripheral nervous system contribution. This systematic review aims to evaluate the utility of skin biopsy as a diagnostic tool for patients with FMS, with special focus on SFP. A comprehensive database search was conducted to identify studies assessing intraepidermal nerve fiber density (IENFD) via skin biopsy in individuals diagnosed with FMS. The included studies demonstrated a reduction in IENFD in a substantial proportion of FMS patients, with reported prevalence ranging widely from 30% to over 85%. Small fiber pathology occurs in a significant proportion of individuals with FMS. Skin biopsy emerges as a valuable diagnostic tool. Further research is needed to better understand the underlying mechanism of SFP in FMS.