[The morphological characteristics of the fibromyalgia syndrome]

Area of Science:

• Histopathology
• Connective Tissue Biology
• Neuropathology

Context:

• Fibromyalgia syndrome (FMS) is a chronic pain disorder characterized by widespread musculoskeletal pain, fatigue, and cognitive difficulties.
• The underlying pathophysiology of FMS remains incompletely understood, with ongoing research into potential cellular and tissue-level changes.
• Dense foci in soft tissues have been proposed as a potential histological marker in FMS.

Purpose:

• To conduct a detailed histological and ultrastructural examination of dense foci in soft tissues from individuals with fibromyalgia syndrome.
• To characterize the composition and microenvironment of these dense foci.
• To investigate the presence of vascularization, innervation, and cellular components within the foci.

Summary:

• Dense foci in fibromyalgia syndrome soft tissues are composed of rough, frequently hyalinized fibrillar connective tissue.
• Vascularization and nervous structures, including thin nervous fibrils and small paraganglia, are observed at the periphery of these foci.
• Electron microscopy revealed severe degenerative changes in collagen fibers and a significant decrease and degeneration of fibroblasts, with an absence of inflammatory signs.

Impact:

• Provides novel ultrastructural insights into the tissue-level alterations associated with fibromyalgia syndrome.
• Suggests a non-inflammatory, degenerative process affecting connective tissue and fibroblasts in FMS.
• Highlights the potential role of peripheral innervation and vascularization in the microenvironment of dense foci.