The hidden tumour: giant anterior mediastinal thymolipoma, an incidental finding.

Thymolipoma is an uncommon, non-malignant mediastinal mass characterized by a mixture of mature fat and normal thymic tissue. It typically grows slowly and is often asymptomatic until it reaches a large size, causing compressive symptoms. We report on a 19-year-old woman who sought medical attention for chest pain, dyspnoea, and anterior chest swelling. Imaging revealed a well-defined anterior mediastinal mass, and surgical excision was performed. Histopathological examination showed a well-encapsulated lesion with mature adipose tissue admixed with normal thymic parenchyma containing Hassall's corpuscles, confirming the diagnosis of thymolipoma. Complete surgical resection is both diagnostic and curative, with an excellent prognosis and negligible recurrence risk. Our findings underscore the importance of recognizing thymolipoma as a potential cause of anterior mediastinal masses, thereby preventing unnecessary radical treatment.