Muscle pathology: dermatomyositis: practice question

A Pathology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pathology · Muscle pathology: dermatomyositis

Sample item

A 38-year-old woman has a violaceous periorbital rash, scaly papules over the knuckles and progressive proximal limb weakness. Serum creatine kinase is markedly raised. Which muscle biopsy finding is most characteristic of her condition?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Perifascicular atrophy with perimysial and perivascular inflammation

Dermatomyositis is a complement-mediated microangiopathy of the perimysial capillaries. Ischaemia of the fibres at the edge of each fascicle produces perifascicular atrophy, with inflammation concentrated around vessels and in the perimysium. The heliotrope rash and Gottron papules separate it from polymyositis.

Option by option

  • A. Ragged red fibres on modified Gomori trichrome staining

    Ragged red fibres indicate a mitochondrial myopathy and not an inflammatory myopathy with skin changes.

  • B. Endomysial CD8 T cells invading non-necrotic muscle fibres

    Endomysial CD8 T-cell invasion of healthy fibres is the pattern of polymyositis, which has no rash.

  • C. Rimmed vacuoles with intracellular inclusions in fibres

    Rimmed vacuoles are seen in inclusion body myositis, which affects older patients with distal and quadriceps weakness.

  • D. Perifascicular atrophy with perimysial and perivascular inflammation (correct)

    Correct. Fascicle-edge ischaemia from capillary injury produces this pattern.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is D, Perifascicular atrophy with perimysial and perivascular inflammation. Dermatomyositis is a complement-mediated microangiopathy of the perimysial capillaries.

Why is "Ragged red fibres on modified Gomori trichrome staining" not the answer?

Ragged red fibres indicate a mitochondrial myopathy and not an inflammatory myopathy with skin changes.

Why is "Endomysial CD8 T cells invading non-necrotic muscle fibres" not the answer?

Endomysial CD8 T-cell invasion of healthy fibres is the pattern of polymyositis, which has no rash.

Why is "Rimmed vacuoles with intracellular inclusions in fibres" not the answer?

Rimmed vacuoles are seen in inclusion body myositis, which affects older patients with distal and quadriceps weakness.

What concept does this question test?

It tests Muscle pathology: dermatomyositis in Pathology. Ischaemia of the fibres at the edge of each fascicle produces perifascicular atrophy, with inflammation concentrated around vessels and in the perimysium. The heliotrope rash and Gottron papules separate it from polymyositis.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Muscle pathology: dermatomyositis?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.