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This quiz will test your diagnostic skills with annular plaques.
Most physicians are aware that tinea corporis (dermatophyte fungal infection) often presents with annular or ring-shaped lesions, hence the term ringworm. However, other ring-shaped plaques are frequently mistaken for fungal infection so it is very important to confirm the diagnosis by potassium hydroxide examination and fungal culture prior to the use of topical and/or systemic antifungal agents.
The illustrations show some common and non-so-common acute and chronic conditions that may readily be confused with fungal infections. The lesions appear as circular or ovoid macules or plaques with an erythematous periphery and central clearing.
For each of the twelve cases, study the image(s) and then answer the questions. You can click on the image to view a larger version if required.
Each case should take approximately 2 minutes to complete. There is a list of suggested further reading material at the end of the quiz.
When you finish the quiz, you can download a certificate.
What is the diagnosis?
Psoriasis
What features distinguish this from other annular plaques?
Psoriasis is typically very persistent and sometimes presents as annular lesions. The plaques are well demarcated and have prominent scale, often silvery in colour. Flakes of skin can be readily brushed off. The lesions tend to be fairly symmetrical in shape and distribution, and may be found on typical sites such as scalp, elbows and knees.