A 21-year-old woman traveled to Florida for spring break, accompanied by her fiancé and friends. While there, she developed a raised, pruritic 10-cm×30-cm lesion on her right lateral chest wall. A local pharmacist thought she was having an allergic reaction and recommended topical hydrocortisone cream and oral diphenhydramine (Benadryl). In spite of this therapy the rash progressed.
Five days after returning home, she presented to the emergency department, where she was diagnosed with herpes zoster. The rash was described as multiple vesicles in a dermatomal distribution on the right side of her torso. She was started on famciclovir (Famvir) and given a prescription for hydrocodone with acetaminophen (Vicodin).
Four days later she presented to her primary care physician because she continued to develop areas of hyperpigmentation around her mouth, on the chin, upper chest and breasts, thighs, and forearms. The original lesion on the right lateral thorax had dried, crusted, and was beginning to peel. It was no longer pruritic. The rash had never been painful and she had not taken any hydrocodone. She was most concerned about the disfigurement caused by the rash and wondered if she was having a reaction to the famciclovir. She had suffered no injuries or trauma, and did not engage in substance abuse.
While in Florida she did sun on the beach with friends, but she used sunblock regularly. She had used the same skin products and sunblock for many years. Upon questioning, she recalled drinking citrus beverages while out in the sun. Her history was otherwise unremarkable. Her only prescription medication before onset of the rash was montelukast (Singulair) prescribed for allergic rhinitis.
Examination revealed a bizarre pattern of hyperpigmentation with small punctate lesions on the upper chest, linear lesions on the posterior right arm and thighs, and broad areas of darkened skin on the lower face and chin (FIGURE 1). There was a broad patch of dense hyperpigmentation with desquamation on that right lateral chest wall that appeared to be healing (FIGURE 2).
FIGURE 1
Vesicles on the trunk…
FIGURE 2
…and anterior chest
What is your diagnosis?