What histologic finding is observed in this case?

 

 

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Answer:  Perifascicular Atrophy in Dermatomyositis

 

This case shows an acquired inflammatory myopathy with well-developed perifascicular atrophy.  Generally speaking, acquired inflammatory myopathies may be morphologically grouped into three categories: Polymyositis, Dermatomyositis, and Inclusion Body Myositis.  The classification of acquired inflammatory myopathies has undergone recent refinement, and additional entities show characteristic morphologic and clinical features (see Pestronk reference).  In the realm of acquired inflammatory myopathies, perifascicular atrophy is characteristic of dermatomyositis. The finding of skin rash in a characteristic distribution on physical exam is helpful, but is not always present (i.e. involvement may be limited to either skin or skeletal muscle muscle). Clinical correlation and follow-up are required as dermatomyositis may be seen in the context of occult neoplasia.

 

References:

“Inflammatory Myopathies.” Muscle Biopsy: A Practical Approach, 4^th ed. Edited by Dubowitz V, Sewry CA, and Oldfors A. Saunders Elsevier, 2013: 513-38

 

Pestronk A. Acquired immune and inflammatory myopathies: pathologic classification. Curr Opin Rheumatol. 2011 Nov;23(6): 595-604

 

Robinson A, Reed A. Clinical features, pathogenesis and treatment of juvenile and adult dermatomyositis. Nat Rev Rheumatol. 7, 2011: 664-75