Experience of the Treatment of Rare Ectopic Hamartomatous Thymoma in the Clavicular Region

Abstract

 Ectopic hamartomatous thymoma (EHT) is an extremely rare, benign, soft tissue tumor characterized by its occurrence in the cervical to sternoclavicular region mainly in middle-aged and elderly men. The border between the tumor and its surroundings is often clear on imaging; however, the interior of the tumor may be heterogeneously delineated, making it difficult to distinguish it from a malignant tumor. Herein, we present the case of an 80-year-old man with a 30 mm subcutaneous tumor on the right clavicle that was initially suspected to be an epidermoid cyst. We excised the cyst via biopsy. Although clinical and imaging findings were inconclusive, histopathological analysis revealed the tumor to be EHT. At the two-year postoperative follow-up, no recurrence was observed. This case highlights the importance of considering EHT in the differential diagnosis of tumors located in the cervical to sternoclavicular region and differentiating them from malignant tumors.