First, although endomysial infiltration of CD8+ T cells is characteristic of polymyositis, it is not prominent and only a few foci of infiltration were observed, making it difficult to consider the case as typical polymyositis.[14] There has also been a case report of a patient with PAN who exhibited myositis on muscle biopsy, similar to this report.[15] Second, considering that the areas that showed myopathic potential on follow-up electromyography were the adductor and vastus muscles, the PAN findings may not have been reflected in the hamstring muscle biopsy. This evidence concerns the gene CD8A and polyarteritis nodosa.