Anti-NXP-2 Dermatomyositis



What?

DM with generalized subcutaneous edema

Pts have more myalgias, more severe weakness, and an increased prevalence of dysphagia than dermatomyositis patients without these autoantibodies.



How?

• Antibodies targeting NXP-2



Manifestations:

• Progressive myalgia

• Proximal and distal muscle weakness

• Generalized nonpitting edema

• Subcutaneous calcinosis

• Dysphagia

• Significant weakness in the neck



Cutaneous Manifestations:

Less likely to have typical DM skin manifestations. But can still have:

• Periorbital heliotrope (blue-purple) rash with edema

• Erythematous rash on the face, or the anterior chest (in a V-sign), and back and shoulders (in a shawl sign)

• Violaceous papules or plaques located on the dorsal part of the MCP or interphalangeal joints: Gottron’s papules

• Palmar papules: can be associated with hyperkeratosis, and complicated of ulcerations

• Skin ulcerations

• Auricular skin lesions: antihelix/helix violaceous macules and erythematous auricular papules



Clinical and Biological Features of Anti-NXP2 Dermatomyositis:

• Muscle atrophy may cause weakness without increasing CK levels

• NXP-2 antibody positive had more severe disease with muscle contractures, atrophy, and diminished functional status



Labs:

Elevated levels of:

• Serum CPK - not always elevated

• Aldolase

• Myoglobin



Association of Anti-NXP2 Dermatomyositis With Malignancy:

Associated with Malignancy:

• Papillary carcinoma

• Clear cell renal carcinoma

• Colon adenocarcinoma

• Non-small-cell lung carcinoma

• Waldenstrom's macroglobulinemia



Lung Manifestations of Anti-NXP2 Dermatomyositis:

• ILD was diagnosed in 7% of anti-NXP-2-positive patients



Treatment of Anti-NXP2 Dermatomyositis:

• Prednisone at 1 mg/kg per day

• In severely ill patients, pulse dose methylprednisolone 1 g/day for three days



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