CD4⁻CD8⁻ T‐cell polymyositis in a patient with chronic active Epstein‐Barr virus infection

Generalized myositis mimicking polymyositis associated with chronic active Epstein-Barr virus infection

“…This pattern is different from CD8+ T cell dominance in polymyositis, CD4+ T cell dominance in dermatomyositis, and CD8+ T cell dominance in some cases of chronic virus myositis [1,2,28]. In the previous reports, the intramuscular infiltrating lymphocytes were CD4-, CD8-(double-negative) and EBV infected T cells in the patients with myositis and CAEBV [24,33]. This pattern is similar to that in our cases.…”

“…This pattern is similar to that in our cases. Even in the other previous reports, those were CD4+, CD8+ (double-positive) EBV infected T cells or CD56+ EBV infected NK cells [24,25,29,33]. These patterns are also different from the patterns of polymyositis and the other conventional myositis.…”

“…These patterns are also different from the patterns of polymyositis and the other conventional myositis. These double-negative or -positive T cells, or NK cells were increased and infected by EBV [24,25,29,33]. These findings suggest that proliferation of EBV-infected T cells with a specific CD4/CD8 expression must participate in the pathogenesis of CAEBV-related myositis, and the difference of phenotype of the intramuscular infiltrating lymphocytes may be helpful to distinguish CAEBV-related myositis from polymyositis and the other conventional myositis.…”

“…Also in our cases, NK cells were few, and EBV infected cells did not express LMP1, as a target of cytotoxic cells. In CAEBV, cytotoxic lymphocyte response to EBV infected cells is impaired [19,33]. These findings may be important to initiate and maintain pathological events in CAEBV-related myositis.…”

“…The biopsy specimen showed intramuscular lymphocytic infiltration in the median rectus muscle. Recently, a 17-year-old woman who had multiple mass lesions in the right thigh and shoulder at the late stage of CAEBV was reported [33]. The biopsy in affected brachial muscles revealed intramuscular infiltration of large lymphoblastoid cells partyly vacuolated or binucleated.…”