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Abstract
Introduction: Melanoma is the most invasive and deadly form of skin cancer. Melanomas are caused by a combination of genetic and environmental factors, with sun exposure being predominantly responsible for most.
Case Presentation: A 90-year-old woman with metastatic melanoma (T4bN1a Stage IIIC), with locally advanced subungual disease of her left great toe, underwent toe amputation and Keytruda (pembrolizumab) therapy. Approximately 1 month into treatment, she developed extensive pruritic ulcers on bilateral lower extremities, with lesions so severe that physicians originally suspected it to be squamous cell carcinoma. However, pathology showed interface dermatitis with eosinophilia, suggesting an allergic drug reaction of epidermal squamous hyperplasia to her melanoma treatment. Despite this, treatment continued until the cancer improved.
Steroid treatment was instituted to treat the lesions topically along with selective intralesional treatment. All lesions received topical clobetasol propionate ointment 0.05% twice a day. Additionally, the 8 most severe lesions (rotating amongst the 20+ lesions) received 0.5 cc Kenalog (triamcinolone 10 mg/cc) injections every 2 weeks. Lesions were selected if raised, pruritic, and >1 cm, and injected in the order of severity, given on a rotational basis, with reinjections for lesions that remained raised. This combination therapy resulted in a decrease of 80-90% of the lesions on her legs over 2-3 months of treatment.
Discussion: Pembrolizumab-caused cutaneous events occur in up to 49% of patients. Combining intralesional Kenalog injections with topical steroids, rather than using topical corticosteroids alone, significantly enhanced the improvement of the patient's lesions and should be considered for treating similar adverse reactions.