Pulmonary hyalinizing granuloma. A limited form of Wegener's granulomatosis?

Pulmonary hyalinizing granuloma is an uncommon disease that consists of slowly enlarging nodules in the pulmonary parenchyma. It occurs rarely: in fact, fewer than 70 case reports have been published in the past 20 years. It is important however in the differential diagnosis of lung diseases manifesting multiple pulmonary nodules. The etiology and pathogenesis of this disorder are unknown. Evidence suggests that the nodules could be the result of a chronic exaggerated immune response to infectious agents or to any other process in which antigen-antibody complexes are involved. More than 50% of the patients reported have evidence of autoimmune phenomena, e.g. positive antinuclear antibodies, a positive rheumatoid factor, or circulating immune complexes. The present report describes, for the first time, a case of pulmonary hyalinizing granuloma in which the patient had antineutrophil cytoplasmic autoantibodies with a granular cytoplasmatic pattern with typical central accentuation of fluorescence intensity and negative nuclei. The presence of antineutrophil cytoplasmic autoantibodies suggests that pulmonary hyalinizing granuloma could be regarded as a localized, non-evolving, form of Wegener's granulomatosis or a purely granulomatous Wegener's granulomatosis.