Prurigo nodularis imitators unmasked.

Abstract

Prurigo nodularis (PN) is characterized by stereotypical, chronic, nodular lesions on the extensor surfaces of the extremities and back. For experienced clinicians, the recognition of this diagnosis is usually not difficult; however, it is essential to consider differential diagnoses and identify PN imitators. We report five patients with severe chronic pruritus who presented with skin lesions resembling PN. They were treated accordingly, but were subsequently diagnosed with a different underlying disease, including nodular marginal zone lymphoma (1 case), delusional parasitosis (1 case), well-differentiated squamous cell carcinomas arising amongst PN lesions (2 cases), and PN-like pemphigus foliaceus (1 case). Critical re-assessment of the diagnosis of PN is important to avoid cognitive biases such as availability bias, anchoring bias, or attribution bias, which could lead to delayed diagnosis of the actual disease, inappropriate treatment, and poorer outcomes.