Fibromyalgia: Three Paradoxes of Diagnosis

Fibromyalgia (FM) is a diagnostic construct defined by clinical criteria, lacking biomarkers
and a gold standard of reference. A non-negligible proportion of patients diagnosed with FM
actually present, either instead or in addition, other often uninvestigated conditions, most notably
small fiber neuropathy (SFN). This article does not propose a new etiopathogenetic theory;
rather, it makes explicit three logical and clinical paradoxes that run through the diagnosis and
management of FM. First paradox: positive criteria exist, but an external validator is missing. The
literature documents overdiagnosis and misdiagnosis, and successive revisions of the criteria have
redistributed the error rather than eliminating it; nonetheless, the diagnosis is often treated as
definitive and may close the door to alternative investigations. Second paradox: FM is frequently
presented to patients as incurable, yet follow-up studies and clinical testimonies report that a
variable proportion of patients improve or no longer meet the diagnostic criteria. These data are
heterogeneous and do not equate to a cure, but they do not justify a uniformly negative prognosis
and deserve to be studied rather than dismissed. Third paradox: in the absence of biological
markers, the diagnosis relies on symptomatic criteria involving cognitive, affective, and somatic
dimensions, and the ICD-11 definition is explicitly biopsychosocial; yet psychological assessment
is not considered a structural part of the diagnostic pathway. It is argued that the three paradoxes
are interconnected and that making them explicit has potential clinical, methodological, and
economic consequences. A summary table lists the main conditions that mimic FM and should
be included in the differential diagnosis. A second paper will address the interoceptive-emotional
integration model and its therapeutic implications.