Efficacy of tacrolimus against Churg-Strauss syndrome in a patient with myasthenia gravis

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Dear Sir: Churg-Strauss syndrome (CSS) is characterized by pulmonary and systemic small-vessel necrotizing vasculitis, and/or extravascular granulomas, eosinophilia and tissue infiltration by eosinophils, occurring in individuals with asthma and often allergic rhinitis or sinusal polyposis. We report the case of a myasthenia gravis (MG) patient who developed CSS and in whom tacrolimus was effective against the eruption of CSS. The patient was a 79-year-old woman diagnosed with MG and asthma 8 years previously who had initially been treated with prednisolone (PSL) 50 mg per os (p.o.) every other day and whose dose had been reduced to PSL 5 mg p.o. every other day. However, because her osteoporosis became more severe, 6 months previously, a switch had been made from PSL to tacrolimus 3 mg daily, and her symptoms had continued to remain under control. Because her blood eosinophil count had recently risen in the absence of any precipitating cause, the increase was suspected of being drug-induced and tacrolimus was stopped. However, when she broke out in a rash 2 weeks later, a drug eruption was suspected, and she was referred to our department. Physical examination showed widespread purpura on her lower legs (Fig. 1a). Laboratory test revealed hypereosinophilia (7.82 9 10/l) with elevated IgE, 901 IU/ml (normal up to 173), and high titers of rheumatoid factor, 82 IU/ml (normal 0–10). Myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) was negative and anti-acetylcholine receptor antibody showed an increased value of 48 nmol/l (normal up to 0.2). Skin biopsy showed necrotizing vasculitis with a marked eosinophilic infiltration. CSS was diagnosed, and when treatment with tacrolimus 3 mg daily was resumed, the eruption almost completely resolved in 1 week (Fig. 1b). CSS is rare, with prevalence of 10.7–13 per million inhabitants [1], whereas the prevalence of MG is 50 per million inhabitants [2]. The exact etiology of CSS is unclear, but an autoimmune process is suggested based on the presence of T cell and eosinophil activation. Although the number of cases has been very small, there have been reports of associations between CSS and autoimmune diseases; however, this is the first report of a case in which there was an association between CSS and MG. The reason for the association between the two diseases in our patient is unknown, but it is very possible that their association was coincidental. Skin lesions occur in 40–75% of patients of CSS [3]. Palpable purpura, often necrotic, on the legs and feet is the most frequent of these manifestations, seen in half of the patients with skin involvement. Various cutaneous manifestations can also be found including petechiae, erythema multiform-like lesions, urticarial wheals, vesicles, ulceration, papules, cutaneous and subcutaneous nodules and livedo reticularis. Tacrolimus was effective in our patient, and ours is the first case in which tacrolimus has been effective. Tacrolimus is a macrolide antibiotic with immunosuppressive properties, which, on molecular basis, is 100 times more potent than that of cyclosporine A (CsA). The most possible mechanism is its ability to inhibit the activation of T lymphocytes. Compared with CsA, the adverse reactions of hypertrichosis and gingival S. Niiyama (&) Y. Amoh K. Katsuoka Department of Dermatology, Kitasato University School of Medicine, 1-15-1 Kitasato, Sagamihara, Kanagawa 228-8555, Japan e-mail: sniiyama@aol.com