From the Guidelines
Granulomatous lung disease is a category of inflammatory lung conditions characterized by the formation of granulomas, with sarcoidosis being a key example, diagnosed based on clinical features, imaging, and other testing as outlined in the American Thoracic Society clinical practice guideline 1.
Definition and Diagnosis
Granulomatous lung disease encompasses various conditions, including sarcoidosis, tuberculosis, fungal infections, hypersensitivity pneumonitis, and granulomatosis with polyangiitis. The diagnosis of these conditions, particularly sarcoidosis, is supported by clinical features such as Löfgren’s syndrome, lupus pernio, uveitis, and erythema nodosum, as well as specific imaging findings like bilateral hilar adenopathy and perilymphatic nodules on chest CT 1.
Clinical Features and Testing
The clinical features supportive of a diagnosis of sarcoidosis, a primary example of granulomatous lung disease, are detailed in the American Thoracic Society guideline 1, including history, physical examination findings, imaging characteristics, and results from other tests such as hypercalcemia or hypercalciuria with abnormal vitamin D metabolism.
Differential Diagnosis
Differential diagnoses for granulomatous lung disease include Erdheim-Chester disease, small-vessel antineutrophil cytoplasmic antibody–associated vasculitides, common variable immune deficiency with granulomatous–lymphocytic interstitial lung disease, and IgG4-related disease 1. Each of these conditions has distinct features that can help in differentiation, such as histopathologic staining for CD68 in Erdheim-Chester disease and elevated serum IgG4 levels in IgG4-related disease.
Management
Management of granulomatous lung disease depends on the underlying cause, with treatments ranging from antimicrobial therapy for infectious causes, corticosteroids like prednisone for sarcoidosis 1, avoidance of triggering antigens for hypersensitivity pneumonitis, to immunosuppressive medications for autoimmune granulomatous diseases.
Symptoms and Prognosis
Symptoms of granulomatous lung disease can vary widely but often include respiratory and systemic symptoms. The prognosis and quality of life for patients with these conditions can be significantly impacted by the disease itself and its treatment, emphasizing the importance of accurate diagnosis and appropriate management 1.
From the Research
Definition and Characteristics of Granulomatous Lung Disease
- Granulomatous lung diseases (GLDs) are a heterogeneous group of pathological entities that can have different clinical presentations and outcomes 2.
- Granulomas are histologically defined as focal aggregations of activated macrophages, Langerhans cells, and lymphocytes, and may form in the lungs when the immune system cannot eliminate a foreign antigen and attempts to barricade it 2, 3.
- The formation of granulomas occurs in the human body if there is a particle which persists in phagocytes and which the immune system cannot eliminate 4.
Types and Classification of Granulomatous Lung Disease
- GLDs can be broadly categorized as infectious or noninfectious, and necrotizing and non-necrotizing granulomatous diseases 2, 5.
- The spectrum of granulomatous lung diseases is broad, including sarcoidosis, tuberculosis, atypical mycobacterial and fungal infection, autoimmune diseases, and occupational lung disease 4.
- Differential diagnosis is challenging due to the numerous different imaging appearances with which GLDs may manifest, and the imaging appearance of some GLDs may mimic malignancy 2, 3.
Diagnosis and Diagnostic Approach
- The diagnosis of GLDs includes clinical evaluation, laboratory testing, and radiological imaging, which especially consists of high-resolution computed tomography, bronchoalveolar lavage, transbronchial needle aspiration or cryobiopsy, and positron emission tomography 2.
- A combined HRCT-pathological approach can be used to assess both the topographical and morphological features of the lesions 6.
- Genetic evaluation can improve the diagnostic accuracy, and an algorithm can be proposed to distinguish infectious from noninfectious GLD 2, 5.