A Case for Diagnosis

History: The patient is an otherwise healthy 67 year-old writer with a three month history of an intensely pruritic papular and pustular dermatitis in an otherwise.  He’s been on Welbutrin, HCTZ and Lipitor for years.   Previously treatments with triamcinolone 0.1% ointment and prednisone for two weeks were not helpful. 

O/E:  There are hundreds of 2 – 3 mm erythematous papules on arms, legs, torso, scalp.  Face spared.  No lesions on hands, feet or genitalia.

Clinical Images:

Pathology:

Lab:  CBC, Chemistries normal.  Wound culure grew 2+ SAUR sensitive to everything.
The patient was treated with Keflex 250 mg qid for a week and Prednisone starting at 40 mg a day.  He cleared quickly, but when he stopped the prednisone after ~ 3 weeks, the eruption and pruritus recurred.  The new lesions are distinct erythematous papules mostly on the torso.  Background looks normal.

Thoughts:  Could this be "subacute prurigo" othewise known as Itchy Red Bump Disease?  I will have slides reviewed and offer another biopsy to the patient.