CRA3 A RARE EVOLUTION: MEDIASTINAL MATURE TERATOMA UNDERGOING SOMATIC-TYPE MALIGNANT TRANSFORMATION TO RHABDOMYOSARCOMA

Hemalatha Munusamy 1, Rozanah Bt Abd Rahman 1, Lim SY 1, Bazli Bin Bahar 1, Azarul 2
1 Department of Respiratory medicine, Hospital Sultanah Aminah, Johor Bahru, Malaysia
2 Department of Respiratory medicine, Hospital Sultan Ismail, Johor Bahru, Malaysia

Mediastinal mature teratomas are typically benign tumours that predominantly occur in the anterior mediastinum. However, rare cases of malignant transformation within mature teratomas have been documented, most commonly involving somatic-type malignancies. This is a case of a 46-year-old female with underlying hypertension, prediabetic mellitus, and a haemorrhagic stroke in 2023 presented with a three-month history of a productive cough and progressive dyspnoea on exertion. The patient's condition did not improve despite completing two courses of antibiotics. Serial chest radiographs revealed persistent right lung consolidation. Investigations for Mycobacterium tuberculosis, including sputum TB Gene Xpert and culture, were negative. A Contrast-Enhanced Computed Tomography (CECT) scan of the thorax was performed, revealing a large mass located in the right upper lobe of the lung extended across the fissure into the right middle and lower lobes, with significant mediastinal extension. The multidisciplinary team (MDT) decided that a Chamberlain procedure, a thoracic surgery technique to obtain a biopsy for further evaluation. Histopathological examination (HPE) revealed a high-grade epithelioid tumour with myogenic and neuroendocrine differentiation, consistent with alveolar rhabdomyosarcoma with neuroendocrine features. The patient underwent chemotherapy. This case report discusses a unique presentation of a mediastinal mature teratoma with somatic-type malignant transformation into rhabdomyosarcoma in a middle-aged female and highlights the importance of considering rare malignancies, such as rhabdomyosarcoma, in the differential diagnosis of a persistent mediastinal mass, though rare, can significantly alter prognosis and treatment strategies.