Skin biopsy findings: implications for the pathophysiology of fibromyalgia

The mechanisms responsible for symptom expression in fibromyalgia (FM) are complex. The most consistently detected objective abnormalities in FM involve pain-processing systems. Up to recently, central nervous system was a primary focus of investigations in FM. Although it is unlikely that FM occurs because of primary disorders of the peripheral tissues, there are still data to suggest that some abnormalities can be detected in the periphery. With the recognition of abnormalities in skin of some FM patients, it is now apparent that the role of peripheral nerve endings in FM is much greater than previously thought. The aim of this paper is to review literature concerning the skin biopsy findings of FM patients and discuss their potential relevance to FM. This paper suggests that patients with FM represent a state of the dysfunction of descending, antinociceptive pathways and low hypothalamic-pituitary-adrenal function. This state is further proposed to result in many skin biopsy findings associated with the disorder, including increased N-methyl-d-aspartate receptors subtype 2D expression, neurogenic inflammation and characteristic electron microscopic findings. Future direction of research would be identification of specific laboratory markers such as skin biopsy for diagnostic and clinical evaluation purposes in FM.