GP Quiz 12 - Case 2.
A 37-year-old man presents with marked scaling in his scalp. He says he has used an anti-dandruff shampoo twice weekly for many years, but it is no longer effective. He attributes the problem to stress.
Describe the appearance.
There is a large patch of thick white scale in the scalp with sticky asbestos-like scales matting the hair shafts. This appearance is known as 'pityriasis amiantacea'.
What is the differential diagnosis?
Pityriasis amiantacea can be due to bacterial infection (Staphylococcus aureus or Streptococcus pyogenes), in which case the underlying scalp is red and moist. More frequently, seborrhoeic dermatitis or psoriasis is responsible.
How might you treat his scalp problem?
The mass of scale must be removed by applications of a tar or keratolytic agent such as coconut oil compound ointment, washed out after an hour or so with a tar shampoo. If the patient does not tolerate tar, prescribe salicylic acid 4% in aqueous cream and ketoconazole shampoo. Repeat daily until clear, then twice weekly as necessary.
The underlying skin disease may need long term treatment. This patient had psoriasis and was later prescribed calcitriol solution to use on the affected areas twice daily.
This quiz was also published by ADIS International in New Ethicals Journal in December 2003.