A muscle biopsy of his right upper thigh was performed and later
revealed many necrotic and regenerating fibers indicating an active
myopathy. Small collections of mononuclear cells were present at
perivascular sites in the perimysium and a few mononuclear cells were
present at the endomysium surrounding necrotic or regenerating fibers.
The biopsy findings could represent necrotizing autoimmune myopathy.
Regarding the patient's clinical correlation, anti-body against HMGCR
was tested, which returned positive at 139.3 CU. The patient was
diagnosed with statin-induced immune-mediated necrotizing myopathy.