When Histiocytosis Masquerades as Mononucleosis: A Case Report.

Langerhans cell histiocytosis (LCH) is a rare disorder predominantly affecting children and is characterized by a wide range of clinical presentations, which can make early identification of the disease difficult and result in the delay of appropriate treatment. The challenge is further compounded by the fact that diagnostic confirmation typically requires a biopsy of the bone or skin lesion, as well as immunohistochemical identification of molecular markers, which may not be readily available in all settings. This case report describes a two-year-old female who was initially misdiagnosed with infectious mononucleosis due to her non-specific presentation, highlighting the diagnostic challenges of LCH, particularly in resource-limited settings. The case highlights the importance of increasing clinical awareness of LCH and including this condition in differential diagnoses to ensure timely and appropriate management.