Dermatomyositis

Which is the most common presenting symptom in dermatomyositis?

Muscle weakness is the most common presenting symptom in dermatomyositis.


Which is the initiating event in pathophysiology of Dermatomyositis?

Initiating event in pathophysiology of Dermatomyositis is the activation of completer factor-3 (C3), which forms C3b and C4b.

Followed by the formation of the neoantigen C3bNEO and the C5b-C9 membrane attack complex (MAC).

Results in humoral mediated attack directed against the muscle capillaries and the endothelium of arterioles. 


What are the Pathognomonic findings of dermatomyositis?

Gottron papules: dorsal metacarpophalangeal and interphalangeal joints may show the presence of overlying erythematous or violaceous papules with or without scaling or ulceration.

Heliotrope rash: This is a characteristic skin finding of dermatomyositis and presents with a violaceous, or an erythematous rash affecting the upper eyelids with or without periorbital edema. This finding may not be apparent in patients with dark skin patients.


What are the Skin findings that may help differentiate dermatomyositis from other conditions?

Gottron sign: erythematous macules or patches over the elbows or knees
Facial erythema: erythema over the cheeks and nasal bridge involving the nasolabial folds. The rash may extend up to the forehead and laterally up to the ears.

Shawl sign: erythema over the posterior aspect of the neck, upper back, and shoulders at times, extending to the upper arms.

V sign: ill-defined erythematous macules involving the anterior aspect of the neck and the upper chest.

Poikiloderma: atrophic skin with changes in pigmentation and telangiectasia in photo-exposed or non-exposed areas.

Holster sign: poikiloderma involving the lateral aspects of the thighs.

Periungual involvement: telangiectasias and cuticular overgrowth

Mechanic’s hands: hyperkeratotic, cracked horizontal lines on the palmar and lateral aspects of the fingers.

Scalp involvement: diffuse poikiloderma, with scaling and pruritis.

Calcinosis cutis: calcium deposits in the skin

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