Papular mucinosis in L-tryptophan-induced eosinophilia-myalgia syndrome

Five patients with the L-tryptophan-related eosinophilia-myalgia syndrome had a generalized eruption of flesh-colored papules. In all patients, histologic examination revealed a focal accumulation of mucin in the upper mid dermis, associated with increased dermal cellularity. The mucin was composed predominantly of hyaluronic acid, with small amounts of sulfated acid mucopolysaccharides. The cells within the lesion were fibroblasts. The lesions slowly regressed after L-tryptophan was discontinued. Proposed explanations for the L-tryptophan-related eosinophilia-myalgia syndrome have centered on contaminants, chemically related to L-tryptophan, introduced in the manufacturing process. Tryptophan metabolites have been linked with sclerotic cutaneous diseases but have not been previously implicated in cutaneous mucinoses.