INTRODUCTION: Primary mediastinal liposarcoma is an uncommon neoplasm of intrathoracic origin. It is usually encountered in later stages when the tumor has become large and symptomatic due to mass effect. Liposarcoma originating in the mediastinum represents less than 1% of mediastinal tumors with less than 150 cases reported in the literature.
CASE PRESENTATION: A 24-year-old man presented to our Emergency Room with severe dyspnea, particularly when laying supine, as well as right shoulder pain over the previous seven days. He denied any cough, fever, chills or chest pain. Serum electrolytes, blood urea nitrogen (BUN) and serum creatinine were all within normal limits. Complete blood count revealed hemoglobin:11.5 g/dL, hematocrit: 34.8%, Mean Corpuscular Volume: 82.9 fl. Chest radiograph revealed marked mediastinal widening and a nearly obliterated right lung field. Upon further questioning the patient was noted to be succesfully treated with surgical excision and chemotherapy for an embryonal rhabdomyosarcoma of the left lower extremity at age 10. He had continued follow-up with his pediatric oncologist until age 20. His family history was also significant for a father who died at age 36 of rhabdomyosarcoma originating in the neck. After hospitalization, computed tomography (CT) of the thorax revealed a large low-density mass originating from the mediastinum and invading the right pleural space,occupying most of the right hemithorax. CT guided biopsy of the lesion revealed myxoid liposarcoma. As he was considered a poor surgical candidate due to the extent of the disease, the patient was initiated on chemotherapy. He underwent 3 months of therapy with modest improvement, but unfortunately succumbed to his cancer before surgical debulking was planned.
DISCUSSIONS: Mediastinal liposarcomas can be difficult to distinguish from other fatty tumors of the mediastinum or thorax, as they have a similar tissue attenuation to fat-containing lesions such as benign lipomas, thymolipomas, or even herniated peritoneal fat. Tissue diagnosis typically requires an excisional biopsy for adequate specimen sampling. Mediastinal liposarcomas tend to vary histologically from myxoid and well-differentiated to dedifferentiated. The primary sequelae from these tumors is from direct invasion and or compression of other thoracic organs such as the heart, great vessels and lung. Surgical excision is the treatment of choice, with chemotherapy and radiation therapy as adjuncts. Unfortunately, in our patient, his inability to lay supine and the severe mass effect on other vital organs made surgery a difficult primary option. Therefore,it was elected to attempt chemotherapy to help reduce tumor size in hopes of secondary resection. Second primary soft tissue sarcomas(STS) as this patient had are also quite unusual, very rarely observed in patients without prior radiation therapy. Recent literature suggests that patients treated for a primary STS had a 0.2% chance of developing a second primary STS. However, there was a higher preponderance amongst those diagnosed with their first primary tumor at a younger age or with a strong family history such as that found in Li-Fraumeni Syndrome.
CONCLUSION: Mediastinal liposarcomas are rare tumors of the chest that tend to grow rapidly and produce severe symptoms. To our knowledge this is the first case of mediastinal liposarcoma in an individual with a previous unrelated sarcoma. This patient highlights the possibility of the need for continued surveillance for secondary malignancy in those with childhood sarcomas.
DISCLOSURE: Arturo Vega, None.