This looks a florid red non scaly rash. It could be many
conditions including drug and viral exanthems. However the distribution of the
rash helps narrow the diagnoses and suggest others. This rash was mainly on sun
exposed areas, outer arms, V of the neck, lower legs below the dress line,
sides of the face with sparing behind the ears. A photo distribution like this
suggests a photo drug reaction particularly to thiazide diuretics or oral
tetracyclines but also brings diseases such as lupus erythematosus into
consideration. Discoid lupus is seen in sun exposed areas but is red and scaly.
The red non scaly variants of lupus are either subacute or systemic. This
patient had subacute lupus with positive ANAs and ENAs particularly the photo
inducing Ro antibodies. A skin biopsy can help but the positive antibodies
really make the diagnosis in the correct clinical setting. Treatment is sun
protection with clothing and sunscreens, topical steroid creams and
hydroxychloroquine until the rash settles.
