A Case of Pembrolizumab Associated SJS/TEN Spectrum Reaction
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Publication Date
4-29-2026
Keywords
oregon, psvmc, psvmc gme, psvmc oaa
Disciplines
Medical Education
Abstract
Introduction: Immune checkpoint inhibitors (ICIs), such as pembrolizumab, are becoming increasingly more common.1 They are associated with a variety of cutaneous immune-related adverse events which can range from drug eruptions to life-threatening Stevens–Johnson syndrome (SJS)/ toxic epidermal necrolysis (TEN) spectrum reactions.2 As use of these ICIs and PD1 inhibitors expands, the incidence of severe dermatologic toxicity can be expected to rise. Early recognition is critical, as SJS/TEN spectrum reactions carry substantial morbidity and mortality compared with drug eruptions. Case report: An 80-year-old female with a history of triple-negative breast cancer on pembrolizumab presented to the ED for evaluation of a worsening rash. She reported that the rash began approximately one month earlier as a pruritic eruption covering an estimated 90% total body surface area. Her oncologist suspected an immune-related cutaneous adverse event secondary to pembrolizumab, with her most recent dose administered one month prior to rash onset. She was started on a prednisone taper, which led to initial improvement of her symptoms. A few days prior to presentation, while still receiving the prednisone taper, the rash progressed and evolved into painful blistering lesions on the buttocks and abdomen, now covering 80% total body surface area. She denied associated fever, fatigue or myalgias. Physical examination revealed scattered vesicles and erosions involving the trunk, buttocks, and extremities, with a negative Nikolsky sign. No mucosal involvement was observed. Dermatology was consulted and performed two lesional punch biopsies for H&E and one perilesional punch biopsy for DIF. The slides were interpreted by a dermatopathologist and showed a partially-detached, necrotic epidermis associated with a vacuolar interface dermatitis. The DIF was negative. These findings were suspicious for a drug reaction in the SJS/TEN spectrum. The patient was treated with methylprednisolone IV 500 mg daily for three days, followed by methylprednisolone 125 mg daily for three days, and subsequently transitioned to an oral prednisone taper beginning at 60 mg daily, which halted the progression of the rash and led to rapid re-epithelialization. Adjunctive topical therapy included triamcinolone 0.1% ointment applied twice daily to the trunk and extremities and hydrocortisone 2.5% lotion applied twice daily to the face and intertriginous areas. Arrangements were made for outpatient dermatology follow-up. Discussion: This case demonstrates the importance of identifying SJS/TEN reactions in patients on ICIs. ICIs are known to significantly increase the risk of SJS/TEN reactions, and pembrolizumab has been shown to be the ICI most likely to cause these reactions. 2, 3 With pembrolizumab being increasingly used in cancer treatment regimens, clinicians must recognize the growing risk of severe cutaneous adverse reactions.1 Early differentiation of life-threatening SJS/TEN spectrum reactions from benign drug eruptions is critical to reduce morbidity and mortality. Increased awareness among providers caring for patients receiving ICIs is essential to ensure prompt diagnosis and timely intervention.
Specialty/Research Institute
Graduate Medical Education
Specialty/Research Institute
Internal Medicine
