Alveolar rhabdomyosarcoma of the anterior mediastinum with vessel invasion in a 4-month-old boy: a case report

Abstract

Introduction: Alveolar rhabdomyosarcomas of the mediastinum in children are rarely reported. Multimodality therapy including chemotherapy, surgery and radiotherapy make up the backbone of the treatment of childhood rhabdomyosarcomas. Complete resection whenever achievable is an important prognostic factor. However, complete resection of tumors in the mediastinum often poses a unique challenge to thoracic surgeons due to their close proximity to important neurovascular structures. Complete resection may not always be possible and judicious peri-operative planning and preparation are required to avoid creating unnecessary surgical morbidities resulting in delay of adjuvant therapy.

Case presentation: A 4-month-old Chinese baby boy was presented to our hospital with stridor, shortness of breath and episodes of cyanosis. Imaging studies found an anterior mediastinal mass compressing the trachea and other neurovascular structures and he was diagnosed to have alveolar rhabdomyosarcoma. Our patient received upfront chemotherapy and subsequently open resection of the mass was attempted via median sternotomy. Intraoperatively, the mass had invaded into the great vessels, precluding a complete resection. Debulking surgery was performed instead and our patient received timely postoperative chemoradiotherapy.

Conclusions: We report a rare case of childhood alveolar rhabdomyosarcoma of the mediastinum with vascular invasion treated with chemoradiotherapy and debulking surgery. Complete resection was not possible due to the close proximity to the great vessels. Different surgical approaches to the mediastinum have been reported in adults and children alike. Regardless of the surgical access, the treatment of childhood rhabdomyosarcomas should be individualized, with careful balance between surgical clearance and surgical morbidity.

Fig. 1

Computed tomographic view of the anterior mediastinal mass compressing and displacing the trachea and great vessels

Fig. 2

a The small round cell tumor arranged mainly in a predominantly solid pattern with a vague alveolar pattern noted focally (in the lower right portion of the image). The majority of the tumor cells are primitive in appearance. Occasional tumor cells with more abundant brightly fibrillar eosinophilic cytoplasm, consistent with rhabdomyoblasts (as indicated by arrows) are noted. (Hematoxylin and eosin stain, original magnification ×400). b On immunohistochemistry, the tumor cells are positive for myogenin and indicative of rhabdomyogenic differentiation. (Immunohistochemical staining for myogenin, original magnification ×400). c Typical fusion transcript of PAX3-FOXO1 was detected by reverse transcription polymerase chain reaction, confirming the diagnosis of alveolar rhabdomyosarcoma

Fig. 3

Intraoperative view of the mediastinal bed following resection showing the slung brachiocephalic vein, brachiocephalic artery (labeled 1), trachea (2), esophagus (3), and tumor encasing the left brachiocephalic vein and left common carotid artery (4)

Fig. 4

Resected specimen containing the bulky thymus and the mediastinal tumor. The tumor is labeled A, with the orientation of the mass marked