A case of tongue granuloma requiring differentiation of Langerhans cell histiocytosis and Erdheim–Chester disease

Granulomatous lesions in the head and neck include Langerhans cell histiocytosis (LCH) and Erdheim–Chester disease (ECD). ECD is a rare non-LCH characterised by histiocytic infiltration of multiple organ systems. In the head and neck region, there are some reports of its occurrence in the bony skeleton; however, it is extremely rare in soft tissues. Herein, we report a case of tongue granuloma requiring the differentiation of LCH and ECD. A 64-year-old man was referred to our hospital for swelling of the tongue and oral floor. We performed a biopsy and diagnosed ECD pathologically. However, as no bone lesions were identified in other parts of the body, a diagnosis of tongue granuloma was made. Following systemic administration of corticosteroids, the swelling of the tongue and oral floor completely disappeared. Steroids were gradually decreased, and there were no signs of recurrence of the disease. This case underscores the importance of considering ECD in the differential diagnosis of granulomatous lesions in the head and neck, even in soft tissues, and highlights the efficacy of corticosteroid therapy in managing associated symptoms.