Erythematous Macular Eruption in an Older Woman

A white woman in her 70s with advanced Alzheimer disease was referred to the hematology clinic for evaluation of a high hemoglobin level (169 g/L; normal range, 120-160 g/L) and red blood cell count (5.67 × 1012/L; normal range, 3.8-4.8 × 1012/L) as well as a generalized itch that was worse after a bath. On examination, she had a florid, erythematous macular eruption over the trunk and limbs (Figure, A) but no hepatosplenomegaly or lymphadenopathy. In addition to the high hemoglobin level, mild lymphocytosis (absolute lymphocyte count, 6.2 × 109/L, range 1.5-4.0 × 109/L) was noted with the lymphocyte morphology, suggesting reactive changes. Skin biopsy specimen (Figure, B) showed a normal epidermis with a pericapillary infiltrate of small lymphocytes restricted to the dermis and no leukocytoclastic vasculitis, fungal organisms, or dermal mucin. The absence of cellular atypia and epidermal involvement suggested a diagnosis of lupus, or gyrate or annular erythema, and the need for clinicopathological correlation.