Acute lupus pneumonitis with normal chest radiograph

Patients with acute lupus pneumonitis (ALP) usually have hypoxemia, patchy infiltrates evidenced on a chest x-ray film, and an incomplete response to corticosteroids with high mortality. In contrast, lupus patients with a syndrome of acute reversible hypoxemia (SARH) have hypoxemia with normal chest x-ray films and a rapid response to corticosteroids. We present a case of biopsy-proven ALP with normal initial chest x-ray films, and a normal CT scan. We hypothesize that a continuum of vascular and parenchymal abnormalities may exist in the lungs of lupus patients. This case also illustrates the insensitivity of routine chest radiographs in demonstrating mild or early pneumonitis.