Quiz
Mixed diagnoses – 10 cases (9 of 11)

For each of the ten 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 five 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.

Case 7

A twenty-year-old male presents with an asymptomatic rash on his trunk and proximal limbs. He tells you the largest patch was the first one and preceded the others by about a week. Individual oval plaques have a collaret of scale as illustrated, and are distributed in a fir tree pattern.

What is the name for this condition?

Pityriasis rosea. The first lesion is known as the herald patch.

Should any specific investigations be performed?

In typical cases, no investigations are necessary. The specific cause of pityriasis rosea is unknown, although viral aetiology is thought likely. However, as the differential diagnosis includes tinea corporis, it may be prudent to do a scraping for mycology. The rash of pityriasis rosea is said to resemble secondary syphilis. The latter is distinguished by accompanying systemic symptoms, oral lesions, extension to the palms and soles, and positive serology.

How long is it likely to persist?

In most individuals the rash clears within eight to twelve weeks. Second episodes are less severe and arise in about 5% of individuals.

What treatment is necessary?

No treatment is necessary in asymptomatic cases. Itch can be severe, and may settle with topical steroids and emollients. Severe cases should be referred to a dermatologist to confirm the diagnosis. Phototherapy may be recommended.

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Quiz Mixed diagnoses – 10 cases (9 of 11)

Case 7

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Quiz
Mixed diagnoses – 10 cases (9 of 11)