D2.303 - Blistering Discovery: A Rare Case of Toxic Epidermal Necrolysis Triggered by Carboplatin and Radiotherapy

INTRODUCTION:

Toxic epidermal necrolysis(TEN) is a rare but life-threatening cutaneous adverse reaction characterized by epidermal detachment affecting more than 30% body surface area along with mucosal involvement. The most common culprits include anticonvulsants and antibiotics.

CASE REPORT: 

We describe the case of a 62-year-old male with a history of bulbospinal muscular atrophy treated with oxcarbazepine since June 2024, and squamous cell lung carcinoma.

In may 2024 the patient initiated carboplatin-paclitaxel regimen combined with pembrolizumab. The first 3 cycles were well tolerated. 

Before the 4th cycle he initiated radiotherapy and subsequently received carboplatin-paclitaxel 24 hours later. Twelve hours post-treatment he developed fever and erythematous plaques on the forearms, which resolved within 72 hours with topical methylprednisolone. The same reaction occurred with the 5th cycle. 

In the 6th cycle the patient underwent another session of radiotherapy, presenting 2-4 hours later worsening of previous lesions and blister formation. He went to the emergency room with a confluent pseudodianiform maculopapular exanthema affecting the trunk and proximal limbs involving over 30% of the skin surface. Skin detachment, positive Nikolsky sign and oral and genital mucous lesions were observed. He was diagnosed with TEN and admitted for treatment with subcutaneous etanercept (50mg) and intravenous methylprednisolone (7 mg/day).

RESULTS: 

Biopsies  revealed a “Lichenoid pattern dermatitis with extensive keratinocyte necrosis and eosinophilia” consistent with erythema multiforme. 

Upon discharge, the patient was advised to avoid aromatic anticonvulsants, platinum agents, and taxanes.

One month post-reaction, the Drug-allergy Unit of Hospital Gregorio Marañón evaluated the patient. Patch testing with  where patch tests with multiple anticonvulsants in DMS (carbamazepine 10%, oxcarbazepine 10, phenytoin 10%, phenobarbital 1%, eslicarbazepine 10%, lamotrigine 10%, levetiracetam 10%, and DMSO control, yielded positive results at 96 hours for all components including the DMSO control. Intradermal testing showed a negative result for paclitaxel at 1 mg/ml and a positive result for carboplatin at 10 mg/ml at 48 hours.

CONCLUSIÓN: 

This case highlights a rare instance of TEN induced by the combination of carboplatin and radiotherapy in a 62-year-old male. The findings underscore the importance of careful evaluation and testing to identify causative agents in severe cutaneous adverse reactions.