Eosinophilic myositis/perimyositis: frequency and spectrum of cutaneous manifestations.

Background: Eosinophilic myositis/perimyositis (EM/P) are a group of rare idiopathic muscle disorders associated with eosinophilia.
Objective: We describe the frequency and spectrum of cutaneous manifestations in EM/P and compare them with the idiopathic hypereosinophilic syndrome (HES).
Methods: We review the literature on EM/P and describe an additional case associated with angioedema.
Results: Of a total of 26 reported patients with EM/P, cutaneous manifestations were observed in 10. These were, in order of frequency, deep subcutaneous induration, erythema, angioedema, urticaria, and papular lesions.
Conclusion: Skin lesions occur less frequently in EM/P than in HES. Although erythematous papulonodular lesions and urticaria/angioedema are most commonly observed in HES, the most frequent skin manifestations of EM/P are subcutaneous induration and erythema. In HES, angioedema has been correlated with a favorable prognosis. At least some of these patients apparently have an idiopathic eosinophilic disorder distinct from HES, including EM/P. In contrast to HES, the overall prognosis of EM/P is good, particularly when muscle lesions are focal, and the principal histopathologic finding is perimysial infiltrates.