To what would you attribute this new skin eruption?

This 35-year-old male presents with a slightly itchy eruption in his groin and axillae of 1 month duration. He is an insulin-dependent diabetic and had a case of pityriasis rosea 2 years prior that resolved uneventfully. He denies any new exposure history, new medications, or recent illnesses. 

To what would you attribute this new skin eruption?

A.  Pityriasis rosea
B.  Drug reaction
C.  Seborrheic dermatitis
D.  Candidiasis
E.  Erythrasma 

(Answer and discussion on next page)

Answer: Inverse PR 

This patient had a case of inverse pityriasis rosea characterized by the characteristic oval-shaped salmon-colored scaling macules involving flexural surfaces rather than being seen on the trunk and proximal extremities. While repeated cases of  pityriasis rosea are uncommon, they have been reported. Seborrhea, Candida infection, and erythrasma would be expected to be more confluent with satellite lesions for the Candida unlike what is seen here. This would be an unlikely appearance for a drug reaction.