Small fiber neuropathy (SFN) is an injury of cutaneous nerve fibers, mainly by a decrease in their density within the cutaneous tissue. The symptomatology associated with this SFN is broad with symptoms that are essentially sensory, but also autonomic. The etiologies of SFN are numerous (diabetes, drug, infectious, immunological...) and clinically non-specific, justifying a broad etiological assessment. The appearance of staged skin biopsies in the SFN balance sheet has greatly helped to improve diagnosis.

Despite this, a significant part of SFN remains without associated etiology and is considered idiopathic.

As the distribution of the different causes of SFN remains a missing data to date, the completion of this cohort study by one of the SFN reference centres should make it possible to establish the prevalence of SFN causes over a large population.

Only patients with clinical symptoms that may be related to SFN and who have been sampled for SFN, positive or not, will be eligible for recruitment.

The result of the anatomopathological sampling will allow patients to be separated into two groups, with or without SFN.

The main judgement criteria will be the prevalence of etiologies associated with SFN: diabetes, medication, systemic lupus erythematosus, Gougerot-Sjögren syndrome, amylosis, dysthyroidism, alcoholism, vitamin B12 deficiency, HIV infection, hepatitis C, paraneoplastic syndrome, hereditary disease (Fabry disease, Friedreich ataxia,...), idiopathic, others.

Inclusion Criteria:

• Age of majority (>18 years old)
• Clinically managed patient at Brest University Hospital
• Patient who had a skin biopsy with anatomopathological examination for SFN performed at the University Hospital of Brest

Exclusion Criteria:

• Under age of majority (<18 years old)
• Patient not followed at Brest University Hospital
• Refusal to participate to the study

Patients with clinical symptomatology in favour of SFN who have been subjected to skin histological examination for SFN

All collected data that underlie results in a publication

Data will be available beginning one year and ending five years following the publication

Data access requests will be reviewed by the internal committee of Brest UH. Requestors will be required to sign and complete a data access agreement.