Persistent microvasculopathy in chronic eosinophilia-myalgia syndrome

Abstract

Acute eosinophilia-myalgia syndrome (EMS) due to contaminated L-tryptophan (LT) exposure is an inflammatory microangiopathy of the dermis, fascia, and muscle. Select individuals evolve from acute EMS to have persistence of myalgia, fatigue, cramps, and skin changes for years. Many develop memory dysfunction and confusion. The objective of this study is to delineate the pathology in individuals with chronic EMS. Seventeen patients with ongoing symptoms representing chronic EMS are studied by skin, fascia, and muscle biopsies four to five years after exposure to contaminated LT and initial onset of EMS. All have microvascular disease. Most have lymphocytic inflammatory infiltrates. Several have dermal sclerosis. The findings indicate that persistent microvascular disease is present in chronic EMS. The pathologic changes are similar to those of acute EMS but with notable differences. Tissue eosinophil infiltration is rare in the chronic state as compared to acute EMS. The degree of inflammation in chronic EMS is markedly reduced compared to acute EMS. The persistence of endothelial pathology indicates continuing microvascular dysfunction.