Recurrent Pleuromediastinal Dedifferentiated Liposarcoma: A case report and literature review
Pleuromediastinal Dedifferentiated Liposarcoma
A 75-year-old patient presented with a 3-week course of progressive dyspnea. Chest X-ray and chest CT were performed.
Initial Chest X-ray (image 1) showed a nearly complete white-out of the right hemithorax with contralateral mediastinal shift, so subsequent chest CT was performed (image 2, 3). A large heterogeneous soft-tissue intrathoracic mass was seen, probably arising from the pleural surface and also invading the prevascular mediastinum. No macroscopic fat could be appreciated in the described lesion. Secondary right lung collapse and left mediastinal shift could also be noted. There was an associated moderate amount of right pleural effusion. The histopathological examination of the core needle biopsy showed infiltration by high-grade atypical cells. Upper right lobectomy was then performed resecting the mass (image 4). The anatomopathological result showed a grade 2 dedifferentiated pleuromediastinal liposarcoma. After eight months, the patient presented dyspnea and respiratory failure. CT scan showed the presence of a new large intrathoracic mass (not shown). As a result, it was decided to perform a new surgical intervention with adjuvant chemotherapy. Multiple pleural nodules were resected; the histology showed a grade 3 dedifferentiated liposarcoma. Six months later the patient presented again with disease progression symptoms. A new CT scan denoted the presence of a right basal pleuromediastinal mass (image 5), along with an infradiafragmatic mass in the falciform ligament (image 6). This second mass was extending into the anterior segments of the right hepatic lobe, and some calcifications could be appreciated inside. These findings suggested metastatic recurrence of her disease and the patient died a few days later.
Liposarcoma is the second most common type of soft-tissue sarcoma . It commonly arises from the retroperitoneum and the extremities, although it can also affect other anatomic locations. However, primary intrathoracic liposarcoma is extremely uncommon . In general, sarcomatous lesions in the thorax are most commonly due to metastases from extrathoracic musculoskeletal tumors, and when primary, they have frequent origin in the chest wall or heart . As to liposarcoma, its clinical, imaging and pathological features highly differ between its five histologic subtypes: well-differentiated, dedifferentiated, myxoid, pleomorphic and mixed . Dedifferentiated liposarcoma has a well-differentiated component and a non-adipose cellular sarcoma component. Affects men and women in similar proportions, with a peak prevalence in the 7th decade . These neoplasms typically have an expansile slow-growing and silent behavior, until they produce symptoms due to mass effect presenting as large or even massive tumors [1,2]. Overall, imaging features of thoracic primary sarcomas are very limited in the literature and they are often based on other more prevalent locations . They tend to be large masses with well-defined contours and heterogeneous density on CT. It is often difficult or either impossible to determine if the tumor is arising from the chest wall, the pleura, the mediastinum or the lungs . Pleural effusion is commonly associated but lymphadenopathies are exceptional . Dedifferentiated liposarcomas share radiological features with well-differentiated liposarcomas, presenting as soft-tissue masses with fat components and nodular nonlipomatous components with thick septa . They occasionally show calcification or metaplastic parts . However, dedifferentiation is based on the non-fatty component, which can be quite large and occasionally dominant, not being able to differentiate fat density on CT on poorly differentiated subtypes [1,2]. These nonadipose foci demonstrate similar attenuation or slightly lower than that of skeletal muscle on CT, and low to intermediate signal intensity on T1-weighted MR images with intermediate to high signal intensity on T2-weighted MR images . According to Ming Chen Et al , in a retrospective analysis of 23 cases of intrathoracic liposarcomas, MRI represents the gold standard for diagnostic evaluation and preoperative planning due to its better definition of the tumor extension and to rule out mediastinal vessel invasion . Nonetheless, CT still remains the primary imaging modality for the initial evaluation of extension, resectability and response to therapy . The treatment approach of dedifferentiated liposarcomas consists of wide surgical excision, usually with adjuvant radiation therapy. Despite the treatment, these kinds of tumors have a high tendency to local recurrence and metastases are seen in 15-20% of cases, predominantly affecting the lungs, liver and bone .