A 56-year-old white man presented with asymptomatic indurated plaques on the flexor aspect of his forearms. The eruption had begun 3 to 4 days after the patient had an influenzalike illness (Figure 1). An initial biopsy specimen showed superficial and deep dermal infiltrates, with plasma cells and eosinophils extending into lobular septa, without vasculitis. Clinically, the process resembled erythema nodosum; however, Borrelia infection was also suspected based on the microscopic findings. The patient was treated with a combination of penicillin and super-saturated potassium iodide (SSKI). Some softening of the lesion occurred. The treatment with super-saturated potassium iodide was discontinued owing to an increase in thyrotropin levels, and colchicine therapy was begun but was later discontinued because of diarrhea. The findings of a second biopsy were thought to be consistent with probable morphea, and calcitriol therapy was initiated. By this time, a confluent nodular induration had developed on the medial aspect of the patient's forearms, with subjective tightening of his legs that extended distally from the medial aspect of his thighs. No photosensitivity, uveitis, colitis, xerostomia, esophagitis, or Raynaud syndrome was noted.
Smith RL, Leaf FA. Indurated Plaques on the Arms. Arch Dermatol. 2002;138(10):1371-1376. doi:10.1001/archderm.138.10.1371