[1829] Biopsy Findings in Acute Pulmonary Histoplasmosis: Unusual Histologic Features of a Potential Mimic of Lymphomatoid Granulomatosis

S Mukhopadhyay, A Katzenstein. State University of New York Upstate Medical University, Syracuse, NY

Background: Most examples of pulmonary histoplasmosis are characterized by necrotizing granulomatous inflammation. Only disseminated histoplasmosis is recognized as causing a different reaction which consists of ingestion of organisms by macrophages without granuloma formation. The histologic features of acute pulmonary histoplasmosis are not well described since this form of the disease is rarely biopsied.
Design: Four surgical lung biopsies of acute pulmonary histoplasmosis were retrieved from consultation files (3) and our surgical pathology archives (1). Each was stained with H&E, Ziehl-Neelsen and Grocott methenamine silver (GMS). Clinical and radiographic findings were documented for all cases, and various histologic features were recorded.
Results: There were 3 men and 1 woman who ranged in age from 40 to 68 years. All presented with fever and other flu-like symptoms for a duration ranging from 3 days to less than 30 days. Radiographically, 3 cases showed a solitary nodular infiltrate while one showed bilateral reticulonodular infiltrates. Histologically, all 4 biopsies showed a parenchymal inflammatory infiltrate composed of lymphocytes and histiocytes filling alveolar spaces and expanding the adjacent interstitium. Large areas of parenchymal necrosis were additionally present in 3 cases. Vasculitis composed of lymphocytes and histiocytes was present in all, and was striking in 3, resulting in a resemblance to grade 1 lymphomatoid granulomatosis (LYG). The tip-off to the correct diagnosis, present in 3 cases, was a few small necrotizing granulomas scattered within the lymphohistiocytic infiltrate. The diagnosis was confirmed by the presence of Histoplasma yeasts in the GMS stain.
Conclusions: Acute pulmonary histoplasmosis may cause a lymphohistiocytic infiltrate with necrosis and vasculitis that is suggestive of LYG. The correct diagnosis is easily established by examination of silver stains. This observation emphasizes the importance of examining special stains for organisms before diagnosing Grade 1 LYG.
Category: Pulmonary

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 254, Tuesday Afternoon


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