Thymic Neuroblastoma within a Thymic Cyst in an Adult

A 65-year-old female patient with no clinical manifestations was hospitalized for examination and treatment of an anterior mediastinal tumor found at the time of a regular health checkup. Enhanced computed tomography (CT) and magnetic resonance imaging revealed a cystic lesion containing a solid tumor. Positron emission tomography-CT demonstrated increased uptake in the solid lesion. Tumor resection with total thymectomy was performed. A pathological diagnosis of thymic neuroblastoma within a thymic cyst was made. Micorscopic examination revealed that tumor cells of the solid component were lined with thymic epithelial cells of the inner cyst wall. Furthermore, some tumor cells of the solid component had melanin granules. These findings suggest that this tumor arose from progenitors of the thymic epithelial cells with the potential to differentiate along neural lines.

Neuroblastoma commonly occurs in children. However, the diagnosis of neuroblastoma in adults has been reported in several case reports. We report an adult case of histogenetically informative thymic neuroblastoma within a thymic cyst. There are no standard treatment strategies and chemotherapy protocols. Complete surgical resection might be important for a better outcome.