What are your recommendations for managing perivascular dermatitis with eosinophils unresponsive to high-dose antihistamines, a prednisone taper, and topical steroids?  

I would check and treat for scabies.

Failure to improve with systemic steroids raises the possibility of hypereosinophilic syndrome that would respond to imatinib or similar drugs. Draw absolute eosinophil count off systemic steroids and if > 1.5 refer to hematology for bone marrow biopsy.

Perivascular dermatitis typically represents pathophysiologic findings that could be caused by a variety of conditions including but not limited to allergic reactions, irritant reactions, infections, or underlying systemic conditions. The presence of eosinophils may be suggestive of an allergic/atop...