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Solitary necrotizing granulomas of the lung: differentiating features and etiology
Abstract:
The clinical and pathologic features of 86 roentgenographically solitary pulmonary granulomas were reviewed to determine etiology and to provide guidelines for histologic evaluation. Fungal or acid-fast organisms were identified within the tissue in 60 cases (70%) and fragments of a helminth were found in one. The organisms were almost always present in the center of necrotic granulomas, and examination of two blocks containing active granulomas was usually sufficient for their identification. Microbiological cultures were less productive than direct examination of the tissue. In 25 cases an infectious etiology could not be identified: two were diagnosed as hyalinizing granuloma, one as Wegener's granulomatosis, and 22 were not further classified. A prominent overlapping spectrum of histologic features was found between infectious granulomas and Wegener's granulomatosis, suggesting that the latter may represent an abnormal immune response to an infectious agent that is no longer identifiable within the tissue. Caution is urged in diagnosing limited Wegener's granulomatosis and other pulmonary angiitides in patients with roentgenographically solitary granulomas.
Insights
Infectious organisms cause most solitary pulmonary granulomas, often found in necrotic centers. Direct tissue examination is key for diagnosis, aiding differentiation from conditions like Wegener's granulomatosis.
Area of Science:
- Pulmonary Pathology
- Infectious Diseases
- Histopathology
Background:
- Solitary pulmonary granulomas are common incidental findings.
- Determining the etiology of these lesions is crucial for patient management.
- Histologic evaluation is essential for accurate diagnosis.
Purpose of the Study:
- To review the clinical and pathologic features of solitary pulmonary granulomas.
- To identify the causative agents and provide diagnostic guidelines.
- To explore the relationship between infectious granulomas and Wegener's granulomatosis.
Main Methods:
- Retrospective review of 86 cases with solitary pulmonary granulomas.
- Histologic examination of tissue for infectious organisms.
- Microbiological cultures for organism identification.
Main Results:
- Infectious organisms (fungal, acid-fast, helminthic) identified in 70% of cases.
- Organisms typically located in the necrotic centers of granulomas.
- Direct tissue examination superior to microbiological cultures for diagnosis.
Conclusions:
- Infectious agents are the primary cause of solitary pulmonary granulomas.
- Histologic evaluation, particularly of active granulomas, is vital.
- Wegener's granulomatosis may represent a post-infectious immune response; caution advised in diagnosis.