D1.234 - The Importance of Differential Diagnosis in DRESS Syndrome: Review of 2 Cases

DRESS syndrome (Drug Rash with Eosinophilia and Systemic Symptoms) is a non-immediate hypersensitivity reaction induced by a drug. Its symptoms include fever, skin manifestations, lymphadenopathy, and multiorgan involvement, accompanied by an increase in eosinophils in laboratory tests. It is a condition with potentially fatal outcomes; however, it is not the only one that might present this clinical picture.

The clinical characteristics and evolution of two patients during their hospital stay are described (Table 1). Both presented temperatures >38.5°C, cutaneous rash, general malaise, and lymphadenopathy. They were also taking a drug for >4 consecutive weeks, leading to a diagnosis of DRESS syndrome.

Treatment was initiated in both cases with methylprednisolone (patient 1: 80 mg/24 hours; patient 2: 60 mg/24 hours) and an antihistamine, with analytical improvement: a decrease in eosinophilia (patient 1: 1200 eosinophils/µL; patient 2: 550 eosinophils/µL), and the normalization of liver enzymes, along with overall clinical improvement.

In patient 1, after a few days, clinical condition and eosinophilia stopped improving, and the patients general condition worsened. A skin biopsy was requested, revealing perivascular and interstitial infiltrates of a mixed inflammatory type predominantly of T (CD3) cells with slight atypia. A lymph node biopsy showed a proliferation of atypical T lymphocytes. Hematology was consulted, and a bone marrow biopsy was performed, leading to a diagnosis of angioimmunoblastic T-cell lymphoma.

In patient 2, when attempting to reduce corticosteroids, skin symptoms reappeared, and eosinophilia increased. A cervical lymph node biopsy showed a proliferation of atypical T lymphocytes, and a PET-CT scan enabled the diagnosis of stage IV-BS peripheral T-cell non-Hodgkin lymphoma.

DRESS syndrome requires early diagnosis to prevent serious complications. However, its clinical presentation can overlap with other conditions, highlighting the importance of considering differential diagnoses with other hypereosinophilic syndromes, especially in cases with wandering or atypical symptoms. Effective and individualized management depends on a comprehensive approach that considers both the evolution of symptoms and the clinical context, which is crucial to establish an accurate differential diagnosis and guide appropriate treatment. This approach is essential to optimize prognosis and improve clinical outcomes in these patients.