Eosinophilia Myalgia Syndrome
Last updated: October 8, 2014
ICD-9 Code: 710.5.
Definition: Eosinophilia myalgia syndrome is considered a variant form of scleroderma. Most cases have been associated with ingestion of L-tryptophan.
Etiology: Ingestion of specific lots of L-tryptophan in 1989–1990 resulted in new cases of eosinophilia myalgia syndrome because of a trace contaminant (1,1′-ethylidene-bis-L-tryptophan) arising from a manufacturing change. Sporadic cases reported since then may be owing to similar trace contaminants in other supplements or to inborn errors of tryptophan metabolism.
Pathology: Full-thickness skin biopsy specimens show thickened fascia with accumulation of collagen in the dermis. Inflammatory infiltrates, which may contain eosinophils, are found in subcutaneous fat (panniculitis) and surrounding small blood vessels or muscle spindles.
Demographics: An epidemic of cases appeared after 1989 and quickly subsided after the suspect preparation was recalled. Most of the epidemic- associated patients were female.
Cardinal Findings: Myalgias are severe and may be debilitating. A minority of patients show muscle enzyme elevations. Skin induration is most commonly seen on the trunk, generally sparing the extremities and face. CNS involvement, manifested by difficulty with memory or other cognitive problems and peripheral neuropathy, occurs in most patients. Uncommonly it results in interstitial lung disease or cardiac involvement with conduction changes and possibly sudden death.
Diagnostic Tests: Peripheral eosinophilia is seen in most patients.
Keys to Diagnosis: Skin thickening and myalgias suggests the diagnosis; rare cases may not be associated with ingestion of L-tryptophan. A full-thickness skin biopsy is needed.
Differential Diagnosis: The skin changes of eosinophilia myalgia syndrome resemble eosinophilic fasciitis. However, eosinophilic fasciitis does not usually exhibit cognitive dysfunction and myalgias. Localized forms of scleroderma and underlying malignancies should be also considered.
Diagnostic Criteria: (a) Eosinophil count >1 X 109/L, (b) generalized myalgias that limit activity, and (c) absence of underlying malignancy.
Therapy: Acute symptoms respond to treatment with glucocorticoids, but late symptoms, including cognitive dysfunction, are relatively resistant to therapy.
Surgery: Surgery is not generally indicated except diagnostic skin biopsy.
Prognosis: A chronic phase develops in more than half of patients, with muscle cramps and CNS abnormalities that may impair normal daily activity.
Pincus T. Eosinophilia-myalgia syndrome: patient status 2–4 years after onset. J Rheumatol 1996;23:19–25 PMID:8895178
Winkelmann RK, Connolly SM, Quimby SR, et al. Histopathologic features of the L-tryptophan-related eosinophilia-myalgia syndrome. Mayo Clinic proc 1991;66:457–463.PMID:1709432