Occupational Head-Butting and Skin Nodules

1Division of General Internal Medicine; 2Division of Infectious Diseases, Department of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan Correspondence and reprints: Dr Karen McClean, Department of Medicine, University of Saskatchewan, 103 Hospital Drive, Saskatoon, Saskatchewan S7N 0W8. Telephone 306-655-1777, fax 306-975-0383, e-mail karen.mcclean@usask.ca CASE PRESENTATION A 28-year-old veterinary student presented with nodules on her forehead. Two weeks earlier, she had been butted in the head by a ram while working with a herd. She sustained a small abrasion over the left frontal area of her head. Six days after the injury, she noted the development of local erythema, swelling and pruritus. She had no fever, chills or systemic symptoms. Self treatment with topical polymyxin B sulfate/bacitracin zinc (Polysporin, Pfizer Inc, USA) yielded no improvement in the lesions. At her initial assessment, two weeks after the injury, an examination showed three lesions above the left eyebrow, one measuring 1.5 cm × 0.6 cm and the other two measuring 0.3 cm to 0.5 cm in diameter. The lesions were vesicular, with an erythematous rim. Lymphadenopathy was not detected and there was no ocular involvement. Within five days after her initial presentation, the lesions became nodular and the erythematous rim more vivid (Figure 1). Tender preauricular lymphadenopathy developed, and she reported fatigue and general malaise but remained afebrile. Aspiration of a lesion was done to obtain material for culture. Hematology and chemistry laboratory investigations were within normal limits. Two days later, she developed fever and chills, with periorbital and facial edema. Blood cultures were negative. Intraocular involvement was ruled out with an examination by an ophthalmologist. Despite 72 h of intravenous clindamycin phosphate (600 mg every 8 h), the edema and lymphadenopathy worsened and she was switched to meropenem 1 g intravenously every 8 h. Improvement was detected within 48 h, and she completed a 10-day course. As the edema resolved, the nodular lesions developed a superficial crust, which subsequently separated, revealing underlying papillomatous lesions. Over the next three weeks, the lesions slowly decreased in size and erythema. Complete healing without scarring ensued. What was the cause of her skin lesions?