How would you diagnose his itchy eruption?

A 79-year-old male presented with a very itchy eruption on his chest of 2 weeks duration. He is otherwise healthy.

How would you diagnose his itchy eruption?

A. Pityrosporon folliculitis
B. Demodex folliculitis 
C. Rosacea
D. Staphylococcal folliculitis
E. Contact dermatitis

(Answer and discussion on next page)

Answer: Demodex folliculitis

A biopsy confirmed the diagnosis of demodex folliculitis which was treated with a topical sulfur/sulfacetamide based wash. Topical crotamiton, oral or topical ivermectin, and topical permethrin have all been reported to helpful. 

Differential diagnosis. Pityrosporon is usually not seen in this age group. Rosacea is a consideration and some think demodex is a type of rosacea. Staphylococcal folliculitis is typically painful and contact dermatitis usually has an exposure history that was not part of this patient’s history.