Single-plaque psoriasis: a single-clue diagnostic challenge

Abstract Introduction: Psoriasis is a chronic, common immune inflammatory condition of the skin, affecting 2-3% of the population, with regional variability. Classically, psoriasis presents as one of the following types: plaque, guttate, inverse, pustular or erythrodermic psoriasis. Typically, the patient will present with several symmetric psoriatic plaques on typical areas of the body, leading the clinician towards the diagnosis of psoriasis. Case report: The present case report series focuses on an atypical presentation of psoriasis noted in 2 patients who presented to our office with a single large, erythematous plaque located on the lower leg. Due to poor response to previous treatment, a biopsy was performed and upon analysis, revealed a diagnosis of psoriasis. The lesions showed significant improvement under local therapy. Conclusion: In spite of significant research on such a common and seemingly well-understood dermatosis, the present case reports plead for further study with regards to atypical presentations of psoriasis.