Rare and Complicated Overlap of Stevens-Johnson Syndrome and Acute Generalized Exanthematous Pustulosis.

Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) and acute generalized exanthematous pustulosis (AGEP) are two separate pathological entities of severe cutaneous adverse reactions (SCARs) with different etiologies and treatment strategies. Diagnosis is, however, complicated by the similarity in their clinical presentation. Although there are few claims of AGEP-SJS/TEN overlap, a simultaneous true overlap of SJS/TEN and AGEP has rarely been described in the literature. Here, we report a case study of a 61-year-old female with a known allergy to sulfa drugs presenting with altered mental status, generalized weakness, and erythematous and excoriated purulent wounds. Based on initial workup and extensive consultation, the patient was diagnosed with severe sepsis secondary to diffuse purulent cellulitis, community-acquired pneumonia, and acute renal failure due to prerenal azotemia from dehydration. She was treated with several antibiotics, starting with vancomycin, piperacillin/tazobactam. Six days later, antibiotics were de-escalated to ceftriaxone and metronidazole because of the patient's improved status. The medications were withheld when the patient started developing extensive blistering on day 8. Blood cultures ruled out any bacterial etiology. Skin biopsy confirmed overlapping features of AGEP and SJS/TEN. Due to the uncontrolled progression of her rash, she was transferred to the burn unit of a higher care center. This is potentially the first histologically confirmed case of AGEP-SJS/TEN overlap in the United States. In this case study, a conclusive diagnosis would have never been made without a biopsy, especially because the condition presented clinically as SJS/TEN. We, therefore, recommend considering a potential overlap of multiple pathologies at each presentation or suspicion of a SCAR and performing an early skin biopsy in order to provide definitive diagnosis and treatment.