PMC7457844_01
Erythema nodosum of the patient. Erythematous subcutaneous nodules in the pretibial area of bilateral lower extremities.
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In June 2019, a 34-year-old woman presented to her primary care provider with painful, swollen erythematous nodules located on the bilateral pretibial areas (Figure 1).
Histopathology of erythema nodosum. (A) Low-power (original magnification x50) and (B) high-power microphotographs of the biopsy showing lymphocyte, neutrophil, and histiocyte infiltration of the interlobular septal in subcutaneous adipose tissue (original magnification x400).
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The histopathology of a biopsy taken from an erythematous nodule on the right leg showed interlobular septal panniculitis, and infiltration with predominately lymphocytes and histiocytes (Figure 2).
Treatments of the patient with anti-SRP-associated immune-mediated necrotizing myopathy. The patient was not responsive to the usual dose of glucocorticoids. Hip flexion power and serum creatine kinase level gradually decreased to normal after rituximab and mycophenolate mofetil were added to the therapeutic  schedule.
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Treatment protocol for this patient was showed in Figure 3.