Non-X-linked hyperimmunoglobulin M syndrome with chronic interstitial pneumonitis.

Hyperimmunoglobulin M (IgM) syndrome is a rare primary immunodeficiency disorder, and the non-X-linked form of this syndrome is even more infrequent. We report the clinical case of a 6-year-old girl. Her disease began at the age of 1 year when she experienced bronchial obstruction. When she was 3 years old she developed severe recurrent respiratory infections of unusual clinical course. Serum IgM was elevated and the other serum immunoglobulins were absent. Cellular immune response was impaired, with severe depression of delayed hypersensitive cutaneous response and of proliferative response to mitogens. The CD40 ligand expression decreased. Chest CT scan showed areas of lung condensation, bronchial dilatation and signs suggesting interstitial pneumonitis. The latter was confirmed by a biopsy showing a high number of Langerhans' cells and an early-stage fibrosis. She was treated with antibiotics, inhaled bronchodilators and corticosteroids, intravenous immunoglobulin, chloroquine and prednisone. Despite the substitution therapy, her clinical course was slow, with respiratory infections and oxygen dependance. The follow-up thoracoscopic biopsy performed after 18 months of immunosuppressant therapy showed a progression of fibrosis and a decrease in the inflammatory infiltrate.