Oral-Onset Langerhans Cell Histiocytosis in a Noncompliant Adult: A Cautionary Case of Multisystem Progression.

Langerhans cell histiocytosis (LCH) is a rare clonal proliferative disorder that may initially present with oral manifestations, posing diagnostic challenges, especially in adults. We report a rare case of a 27-year-old male who initially presented with painful ulcerative palatal lesions and advanced periodontal symptoms. Despite early biopsy-confirmed LCH diagnosis and haematology referral, the patient's noncompliance led to delayed treatment, resulting in progression from localised oral involvement to multisystem disease, including mandibular, iliac, and vertebral bone lesions. Treatment ultimately required systemic chemotherapy after repeated biopsies and positron emission tomography/computed tomography imaging confirmed disease dissemination. Dental extractions and soft tissue excision were performed to manage oral symptoms. This case highlights the critical role of dental professionals in early LCH detection and underscores the impact of delayed intervention. Interdisciplinary collaboration and patient compliance are essential to prevent disease progression and improve outcomes in LCH with oral involvement.