A Case of Giant Mediastinal Liposarcoma of Thymic Origin: A Rare Clinical Entity

Thymoliposarcoma is an exceedingly rare tumor of thymus with a very few cases reported till date. This case study presents a 45-year male with rare type of thymoma. On the contrast-enhanced CT images, there was a large mass lesion of predominantly fat attenuation in the pre-vascular compartment of the mediastinum insinuating on both sides of the visceral compartment of the mediastinum, and extending upto the bilateral cardio phrenic and anterior costophrenic angles, anterior to the right ventricle with loss of fat plane with the pericardium, with few sub-centimetric lymph nodes in the right paratracheal and AP window and a calcified right hilar lymph node, suggestive of well-differentiated liposarcoma/thymoliposarcoma. Initial CT guided tru-cut tissue biopsy was inconclusive, and the repeat biopsy revealed as fibro-collagenous tissue with area of necrosis, focal myxoid changes in the background with presence of cells which are spindle to oval in shape with mild nuclear pleomorphism and negative for S100, Cytokeratin, CD34, desmin. The entire tumor was resected en masse after meticulous dissection without the support of cardiopulmonary bypass (CPB) with an intact pericardium. Final histopathology report of the surgical biopsy specimens is consistent with dedifferentiated thymoliposarcoma with focal ganglionic cell differentiation. Postoperative follow-up CECT of thorax revealed no evidence of residual mass in the pre-vascular compartment. The patient is disease-free and asymptomatic after 6-month and he is under routine follow-up under Radiotherapy department since he received 30 Gy of postoperative radiotherapy (PORT).