Difficulties of differential diagnosis of fibromyalgia

Chronic widespread pain is the leading symptom of fibromyalgia (FM). However, it is not unique to FM; other diseases may also manifest as chronic pain syndrome. This requires differential diagnostics. The latter is a difficult task, since, on the one hand, it is necessary to know the clinical picture of FM, modern diagnostic criteria and be able to use them in practice. According to a survey among doctors on knowledge of the diagnostic criteria of FM, only 10% of specialists were able to reproduce the diagnostic criteria. On the other hand, the doctor must remember the list of conditions that mask FM. Diseases that may accompany or imitate FM include rheumatological, neurological, musculoskeletal, endocrine, gastrointestinal, infectious pathology, and may also be associated with medication. Concomitant psychiatric pathology worsens the course of FM. The diagnostic search is complicated by the lack of a clearly defined biomarker for FM to date. The article presents the modern criteria of FM of the American College of Rheumatology (ACR), 2011/2016, which showed greater diagnostic validity compared to criteria AAPT, 2019. According to the modern concept, FM is a diagnosis of exclusion, but this does not exclude the presence of several nosologies at the same time. The main diagnostic points of differential search are also disclosed. Knowledge of differential diagnostics will help to make a timely correct diagnosis and increase the chance of successful treatment of patients with chronic pain syndrome. The purpose of the work is to review the literature on diagnostic criteria and diseases that can imitate FM, and to highlight the signs that can distinguish these various diseases from FM.