Interstitial lung diseases belong to a group of diseases that typically exhibit a
subacute or chronic progression but that may cause acute respiratory failure. The
male patient, who was 37 years of age and undergoing therapy for non-Hodgkin's
lymphoma, was admitted with cough, fever, dyspnea and acute hypoxemic respiratory
failure. Mechanical ventilation and antibiotic therapy were initiated but were
associated with unfavorable progression. Thoracic computed tomography showed
bilateral pulmonary "ground glass" opacities. Methylprednisolone pulse therapy was
initiated with satisfactory response because the patient had used three drugs related
to organizing pneumonia (cyclophosphamide, doxorubicin and rituximab), and the
clinical and radiological symptoms were suggestive. Organizing pneumonia may be
idiopathic or linked to collagen diseases, drugs and cancer and usually responds to
corticosteroid therapy. The diagnosis was anatomopathological, but the patient's
clinical condition precluded performing a lung biopsy. Organizing pneumonia should be
a differential diagnosis in patients with apparent pneumonia and a progression that
is unfavorable to antimicrobial treatment.