Differential diagnosis of granulomatous lung disease: clues and pitfalls: Number 4 in the Series "Pathology for the clinician" Edited by Peter Dorfmüller and Alberto Cavazza

Abstract

Granulomatous lung diseases are a heterogeneous group of disorders that have a wide spectrum of pathologies with variable clinical manifestations and outcomes. Precise clinical evaluation, laboratory testing, pulmonary function testing, radiological imaging including high-resolution computed tomography and often histopathological assessment contribute to make a confident diagnosis of granulomatous lung diseases. Differential diagnosis is challenging, and includes both infectious (mycobacteria and fungi) and noninfectious lung diseases (sarcoidosis, necrotising sarcoid granulomatosis, hypersensitivity pneumonitis, hot tub lung, berylliosis, granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, rheumatoid nodules, talc granulomatosis, Langerhans cell histiocytosis and bronchocentric granulomatosis). Bronchoalveolar lavage, endobronchial ultrasound-guided transbronchial needle aspiration, transbronchial cryobiopsy, positron emission tomography and genetic evaluation are potential candidates to improve the diagnostic accuracy for granulomatous lung diseases. As granuloma alone is a nonspecific histopathological finding, the multidisciplinary approach is important for a confident diagnosis.

FIGURE 1

Chest high-resolution computed tomography (HRCT) of a–c) acute hypersensitivity pneumonitis and d–f) chronic hypersensitivity pneumonitis. Chest HRCT of acute hypersensitivity pneumonitis shows bilateral ground-glass densities with centrilobular micronodular accentuation and minor consolidation. Chest HRCT of chronic hypersensitivity pneumonitis shows bilateral reticular shadowing, traction bronchiectasis and minor mosaic perfusion along with some micronodules.

FIGURE 2

Diagnostic algorithm of granulomatous lung diseases. OP: organising pneumonia; EGPA: eosinophilic granulomatosis with polyangiitis; NSG: necrotising sarcoid granulomatosis; GPA: granulomatosis with polyangiitis; GLILD: granulomatous–lymphocytic interstitial lung disease; HP: hypersensitivity pneumonitis; PLCH: pulmonary Langerhans cell histiocytosis.