LAUSR

Dear Editor, Polymyositis and dermatomyositis are generally considered to be autoimmune disorders because of the presence of various autoantibodies against nuclear and/ or cytoplasmic antigens, including antibodies that react with aminoacyl transfer RNA synthetase, signal recognition particle, and Mi-2. Intriguingly, these autoantibodies, known as myositis-specific autoantibodies (MSAs), are specific to polymyositis/dermatomyositis and are associated with clinically distinct subsets of these disorders. Recently, anti-transcription intermediary factor (TIF)-1c antibodies were identified as MSAs, and are strongly associated with internal malignancy but not interstitial lung disease. Panniculitis is a rare cutaneous manifestation of dermatomyositis characterized by generally tender subcutaneous nodules on the arms, buttocks, thighs and abdomen, and histologically nodular panniculitis with lymphoplasmacytic infiltration. Thus far, little is known about the association between panniculitis and MSAs. A 40-year-old Japanese woman with a 6-year history of dermatomyositis was referred to us with painful, indurated, subcutaneous nodules in the axillae bilaterally and on the abdomen. Six years earlier, she had presented with erythema on the eyelids; keratotic erythematous plaques on the elbows, knees and the dorsal aspects of the fingers, erythematous lesions on the neck and chest, and proximal muscle weakness. Laboratory investigations showed raised serum creatine kinase, aldolase and erythrocyte sedimentation rate. Antinuclear antibody test was positive at 1 : 320 with a speckled pattern, whereas anti-Sj€ ogren’s syndrome-A/B, anti-Jo-1, anti-U1-ribonucleoprotein, anti-DNA, and anti-Sm antibodies were all negative. Computed tomography did not show interstitial lung disease. No internal malignancy was found. A diagnosis of dermatomyositis was made on the basis of these findings. The patient was initially treated with prednisolone at 60 mg/day with gradual improvement of her muscular and skin symptoms. Subsequent tapering of the prednisolone dose down to 10 mg/day resulted in recurrence of her muscular and skin symptoms. Subsequently, methotrexate at 4 mg weekly was added 2 years before referral, resulting in mild improvement in muscular symptoms but not skin symptoms. One year before referral, multiple subcutaneous nodules appeared. Physical examination revealed multiple, tender, indurated, subcutaneous nodules without overlying erythema on the bilateral axillae and the abdomen (Fig. 1a). She also had poikilodermatous erythema on the neck and chest (Fig. 1b) and keratotic erythematous plaques on the elbows, knees and the dorsal aspects of her fingers. We initially suspected a methotrexateassociated lymphoproliferative disorder and discontinued methotrexate. Whole-body computed tomography for malignancy screening did not show any abnormalities. Histological examination of the subcutaneous nodules on the right axilla and abdomen revealed lobular lymphoplasmacytic panniculitis with fat necrosis and membranocytic changes in the subcutaneous fat, but nuclear atypia was absent (Fig. 1c,d). Calcification was not observed. There were no histological changes in the epidermis and dermis. Direct immunofluorescence was negative. Consequently, a diagnosis of dermatomyositisassociated panniculitis was made. Cyclosporine at 150 mg daily was added, resulting in a gradual reduction of the indurated nodules. Her muscular and skin symptoms were also improved. Afterwards, the immunoprecipitation assay using the patient’s serum revealed the presence of anti-TIF-1-c/a/b antibodies (Fig. 2). The TIF-1 family, a subgroup of the tripartite motifcontaining proteins, consists of several members, including TIF-1a, TIF-1b and TIF-1c. Fujimoto et al. have reported that 78 of 456 (17%) patients with dermatomyositis had at least one or more anti-TIF-1 antibodies. Among them, 52 of 78 (67%) patients were positive for both TIF-1c and TIF-1a, while 25 of 78 (32%) were positive for TIF-1c alone. Only four of 78 (5.1%) patients were positive for TIF-1c, TIF-1a and TIF-1b, indicating that anti-TIF-1-c/a/b antibody-