Diagnosis of Acute, Chronic (with and without Nasal Polyps), and Fungal Sinusitis.

Rhinosinusitis is a spectrum of diseases with varied causes, presentations, and diagnostic approaches-from viral and bacterial acute rhinosinusitis to chronic inflammatory or fungal etiologies. This article reviews the diagnosis of acute, chronic, recurrent, and fungal rhinosinusitis, highlighting key clinical, endoscopic, and radiologic features that distinguish these entities. It provides practical guidance on differentiating viral from bacterial causes, assessing chronic inflammation with and without polyps, and recognizing rare but serious fungal infections. It also explores emerging diagnostic tools such as biomarkers and artificial intelligence that are reshaping personalized care in sinusitis.