Mycosis fungoides with Sézary syndrome mimicking erythrodermic drug eruption

Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common subtypes of cutaneous T‑cell lymphomas (CTCLs), but their presentation can often mimic other dermatological conditions, leading to diagnostic challenges. This case report presents a rare occurrence of mycosis fungoides with Sézary syndrome (MF-SS) that initially mimicked an erythrodermic drug eruption. Despite therapeutic efforts, the patient succumbed to septic shock following the first cycle of CHOP chemotherapy (cyclophosphamide, doxorubicin, vincristine, and methylprednisolone). This case underscores the importance of a meticulous diagnostic approach in erythroderma and highlights the therapeutic challenges associated with MF-SS.

A 25-year-old woman presented with generalized pruritus and erythematous papules after consuming a fish-based diet. Despite taking multiple medications, her symptoms worsened, progressing to generalized erythroderma with facial erythema, fissures, and scaling, leading to an initial suspicion of drug eruption. However, histopathology, immunohistochemistry, and a peripheral blood smear ultimately confirmed a diagnosis of MF-SS. Initial management with intravenous steroids, methotrexate, and cyclosporine provided mild improvement, but the patient developed fever, chills, and septic shock. She was switched to cyclosporine after methotrexate was found ineffective. She received her first cycle of CHOP chemotherapy, but her condition deteriorated rapidly. Thus, she decided not to continue chemotherapy regimens and not to attend routine outpatient control. Re-admitted 4 months later with generalized weakness and skin desquamation, she was diagnosed with septic shock and multiorgan dysfunction. Despite aggressive fluid resuscitation, antibiotic therapy, and supportive care, she succumbed to septic shock.

This case report highlights the difficulty in diagnosing MF-SS due to its ability to mimic other dermatological conditions like drug eruptions. It also underscores the severe complications and high mortality associated with treating advanced MF-SS, particularly with combination chemotherapy. The report advocates for increased awareness and precision in similar cases and emphasizes the need for a multidisciplinary approach in managing this challenging malignancy. Early and accurate diagnosis can help tailor more effective treatment strategies and improve patient outcomes.