When “Sinusitis” Is Actually Cancer: Diagnostic Red Flags for Unilateral or Refractory Sinonasal Disease

Sinonasal malignancies are rare, accounting for fewer than 3% of head and neck cancers, but their early presentation often overlaps with benign rhinosinusitis. Unilateral nasal obstruction, rhinorrhoea, facial pressure, and intermittent epistaxis may initially appear inflammatory, which contributes to diagnostic delay and late-stage presentation. Recent clinical guidance emphasizes that persistent unilateral symptoms, especially when accompanied by bleeding, focal endoscopic abnormalities, or orbital, dental, or neurologic features, should prompt specialist assessment rather than repeated empiric treatment. This commentary argues that the central clinical problem is not failure to recognize advanced disease, but failure to reconsider a benign working diagnosis when “sinusitis” stops behaving like sinusitis. This commentary proposes a pragmatic triage framework for unilateral or refractory sinonasal disease that prioritizes pattern recognition, focused nasal endoscopy, appropriate imaging, and timely biopsy where indicated. Its contribution is to connect three clinically relevant observations: sinonasal malignancy is rare and therefore easily deprioritized; unilateral, progressive, refractory, bleeding, orbital, dental, or neurologic features should prompt earlier cancer exclusion; and emerging AI-assisted endoscopy should currently be viewed only as a triage adjunct, not a substitute for imaging, histopathology, or multidisciplinary assessment.