A 34-year-old man with HIV/AIDS and a CD4 count of 45 cells/μL presents to the emergency department with a 5-day history of progressive dyspnea, nonproductive cough, and fever to 38.9°C. His oxygen saturation is 88% on room air, respiratory rate is 24 breaths per minute, and blood pressure is 118/76 mmHg. Chest X-ray demonstrates bilateral diffuse interstitial infiltrates, and serum LDH is elevated at 520 U/L. PCR testing confirms Pneumocystis jirovecii pneumonia. He is initiated on high-dose trimethoprim-sulfamethoxazole and adjunctive dexamethasone given his hypoxemia. On day 4 of therapy, he develops a diffuse maculopapular pruritic rash over his trunk and extremities accompanied by recurrent fever to 38.6°C and mild periorbital edema. Which of the following is the most likely etiology?

1. A)Secondary infection with Pneumocystis jirovecii in the skin
2. B)Trimethoprim-sulfamethoxazole hypersensitivity reaction, more common in HIV-infected patientsGABARITO
3. C)Concurrent development of acute leukemia from long-term sulfonamide use
4. D)Dexamethasone-induced dermatitis from immunosuppression
5. E)Immune reconstitution inflammatory syndrome caused by antiretroviral therapy