Abstract: Methotrexate is one of the most used drugs in the treatment of psoriasis with indication of systemic therapy. Cutaneous and mucous side effects are described by pharmacological characteristics of the drug itself or due to overdose. We report the case of a patient with ulcerations in oral mucosa and psoriatic plaques after incorrect use of Methotrexate. Prescribed in a weekly dose, it was used continuously for 10 days and without simultaneous intake of folic acid. It is important to ensure correct comprehension of the prescription.

Neste estudo é relatado o caso de um paciente do sexo masculino, 14 anos de idade, que após fazer grande esforço vocal, durante uma partida de futebol, desenvolveu quadro agudo de dor torácica. As radiografias de tórax e a tomografia computadorizada evidenciaram pneumomediastino, com pequeno pneumotórax bilateral. Os exames clínico, laboratoriais e radiológicos não demonstraram qualquer fator predisponente, ficando o caso classificado como pneumomediastino espontâneo.

The present article reports the case of a 14-year-old male patient who developed acute chest pain following increased vocal effort during a soccer game. Chest radiography and computed tomography demonstrated pneudomediastinum with small bilateral pneumothorax. Clinical, laboratory and radiological studies did not demonstrate any predisposing factor, and the case was classified as spontaneous pneudomediastinum.