Hilar and Mediastinal Lymphadenopathy as a Potential Manifestation of Azathioprine-Associated Hypersensitivity Syndrome.

Azathioprine-associated hypersensitivity syndrome is a rare, idiosyncratic, dose-independent reaction that typically develops within the first four weeks of therapy. The clinical presentation includes a broad spectrum of symptoms such as fever, gastrointestinal manifestations including abdominal pain, nausea, and vomiting, cutaneous involvement, arthralgias, myalgias, and organ dysfunction, particularly affecting the liver and kidneys. Laboratory findings typically include leukocytosis, neutrophilia, and elevated C-reactive protein (CRP), whereas eosinophilia is usually absent. To date, lymphadenopathy has not been described as a manifestation of this syndrome. In this report, we describe the case of a 75-year-old female patient who developed a probable azathioprine-associated hypersensitivity syndrome three weeks after treatment initiation and who, in addition to systemic manifestations of the syndrome, presented with bihilar and mediastinal lymphadenopathy, which may represent a previously unreported feature of this condition, and we discuss potential differential diagnoses.