Perifascicular atropy of muscle fibres is seen in?
**Core Concept**
Perifascicular atrophy of muscle fibers refers to the selective wasting of muscle fibers at the periphery of the fascicle, which is a characteristic histopathological feature of certain myopathies. This phenomenon is associated with muscle fiber injury and subsequent regeneration, leading to the formation of atrophic fibers.
**Why the Correct Answer is Right**
The correct answer is associated with dermatomyositis, an autoimmune inflammatory myopathy characterized by skin and muscle involvement. Perifascicular atrophy is a hallmark feature of dermatomyositis, resulting from the autoimmune-mediated damage to muscle fibers. The pathogenesis involves the deposition of complement components and the activation of immune cells, leading to muscle fiber injury and atrophy.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because perifascicular atrophy is not typically seen in polymyositis, which is another autoimmune inflammatory myopathy that primarily affects the muscle. While polymyositis can cause muscle weakness and atrophy, the histopathological features are distinct from those seen in dermatomyositis.
**Option B:** This option is incorrect because perifascicular atrophy is not a characteristic feature of inclusion body myositis, a degenerative myopathy that affects older adults. Inclusion body myositis is characterized by the presence of inclusion bodies within muscle fibers, but not perifascicular atrophy.
**Option C:** This option is incorrect because perifascicular atrophy is not typically seen in muscular dystrophy, a group of inherited disorders that affect muscle strength and function. While muscular dystrophy can cause muscle atrophy, the histopathological features are distinct from those seen in dermatomyositis.
**Clinical Pearl / High-Yield Fact**
Perifascicular atrophy is a key histopathological feature that helps distinguish dermatomyositis from other myopathies, making it an important diagnostic clue in clinical practice. This feature is often highlighted in muscle biopsy specimens, and its recognition can aid in the diagnosis of dermatomyositis.
**Correct Answer: D. Dermatomyositis.**