Necrotic Pulmonary Nodules and Crohn Disease

Context: Extraintestinal pulmonary manifestations of inflammatory bowel disease (IBD) are uncommon but protean, and include necrobiotic nodules, defined as sterile aggregates of neutrophils with necrosis, with/without epithelioid histiocytes. The etiology of necrotic pulmonary nodules in patients with IBD poses a diagnostic dilemma and includes malignancy, autoimmune disease, infection (treatment with immunosuppressives), and IBD involving the lung. Necrobiotic nodules, although rare in IBD, have been described appreciably more often in ulcerative colitis than in Crohn disease. The aim of this study was to determine the frequency and etiology of necrotic pulmonary nodules in Crohn disease. Design: Surgical pathology reports for all lung and pleural specimens evaluated at our institution between 2000-2014 were searched for terms related to necrotic nodules/granulomas. The medical records of these patients were examined to identify those with IBD. Finally, the histopathology was reviewed in patients with IBD and necrotic pulmonary nodules. Results: Of the 175 cases identified with necrotic pulmonary nodules, 5 were associated with Crohn disease and 1 with ulcerative colitis. In the Crohn disease cases, secondary causes such as infection were excluded, and all 5 cases met the histopathologic criteria for necrobiotic nodules. The single case of ulcerative colitis was culture positive for Mycobacterium tuberculosis. Conclusions: Crohn disease as a primary etiology for necrotic pulmonary nodules is not as rare as presently believed, and may represent the most frequent cause in patients with Crohn disease. It is important to be aware of this to avoid delay in diagnosis and in instituting appropriate therapy.