Comment faire le diagnostic de dermatopolymyosite?

Aujourd hui en rheumatologie, nous voyons une jeune patiente de 16 ans pour deuxieme avis medical (apres le MGH) pour des lesions des mains, des pieds et du cou, dont elle se plaint depuis deux ans. Differents dignostics ont ete poses, dont lupus, arthrite psoriasique, chondrocalcinose, dermatopolymyosite...les parents sont un peu perdus et la jeune fille a recu differents traitements sans amelioration.Elle est actuellememt tres genee par ses lesions des mains inflammatoires, rouges et douloureuses ressemblants a la photos ce dessus, ses lesions du cuir chevelu d allure psoriasique, des plaques squameuses de la nuque et une eruption des joues en ailes de papillon assez discrete, ainsi que sur les paupieres

Le grand Professeur n a pas de doute clinique, contrairement a moi...alors comment faire le diagnostic? sur la clinique caracteristique: les lesions cutanees et la legere raideur musculaire

The main symptoms include skin rash and symmetric proximal muscle weakness which may be accompanied by pain. The pain may resemble the type experienced after strenuous exercise. Some DM patients have little pain, while in others (esp. in JDM: juvenile DM), the pain may be severe. It is important to remember that this condition varies from person to person in many ways. Also in many cases muscle may deteriorate and render the infected temporarily paralyzed unable to walk, run, get out of bed, or even swallow food and liquids.

Skin findings occur in DM but not PM and are generally present at diagnosis. Gottron's sign is an erythematous, scaly eruption occurring in symmetric fashion over the MCP and interphalangeal joints (can mimic psoriasis). Heliotrope or "lilac" rash is a violaceous eruption on the upper eyelids, often with swelling (most specific, though uncommon). Shawl sign is a diffuse, flat, erythematous lesion over the back and shoulders or in a "V" over the posterior neck and back, with UV light. Erythroderma is a flat, erythematous lesion similar to the shawl sign but located in other areas, such as the malar region and the forehead. Periungual telangiectasias and erythema occur.

Mechanic's hands (also in PM) refers to rough, cracked skin at the tips and lateral aspects of the fingers forming irregular dirty-appearing lines that resemble those seen in a laborer. Psoriaform changes in the scalp can occur. Centripetal flagellate erythema comprises linear, violaceous streaks on the trunk (possibly caused by itching pruritic skin). Calcinosis cutis (deposition of calcium in the skin) is usually seen in juvenile DM, not adult DM. Dysphagia (difficulty swallowing) is another feature, occurring in as many as 33% of cases.