Primary pulmonary sarcomas are extremely rare, and can be found in 0.1 to 0.5% of all pulmonary neoplasm cases. The most common sarcomas include leiomyosarcoma, malignant fibrous histiocytoma, and synovial sarcoma [6, 7]. Symptoms and radiologic appearances are similar to those of more common lung carcinomas. The radiological features of the sarcomas are variable, not lesion-specific, and not sufficient to suggest specific diagnosis [8]. Presentation of the disease depends more on tumor localization than histopathological features [9]. After epithelial malignancy is ruled out, the most important differential diagnosis of primary pulmonary sarcoma is metastatic spread from an extrapulmonary sarcoma. Other differential diagnoses include pleomorphic lung carcinoma, pulmonary sarcomatoid carcinoma, and malignant melanoma. Therefore, a detailed medical history and appropriate diagnostic examination is necessary to specify that the tumor has primary pulmonary origin. As patients diagnosed with pulmonary sarcoma are quite rare, it is difficult to define a reliable management protocol for such patients [2].
Immunohistochemistry has an important role for accurate diagnosis and classification of sarcoma type. It is often positive for keratin, actin, desmin, EMA, CD99, and CD34, but positive stains usually do not help diagnosis, so UPS is a diagnosis of exclusion [10]. In our case, there was no evidence of epithelial differentiation. The S-100 protein, which can be found positive in malignant peripheral nerve sheath tumor and melanoma, was negative. Synovial sarcoma is characterized by mast cells within the tumor, but none were detected in this case. Characteristic translocation for synovial sarcoma was negative. Microscopic description characteristic for UPS was also present in the tumor tissue of our patient: storiform pattern, irregular fascicles, variable cellularity, and pleomorphic and bizarre tumor cells with foamy cytoplasm and marked atypia; on the background of inflamed collagenous stroma, multinucleated giant cells were seen, also numerous mitotic figures, including atypical forms. Grading of tumor was determined as per FNCLCC system criteria.
Treatment options are based on algorithms used in treatment of extremity lesions with the well-established role of wide surgical resection aiming for tumor-free margins as the primary therapeutic modality. Some authors found that completeness of resection was correlated with significantly increased survival, but size and grade of tumor were not [11]. Radical resection is established as the only treatment that can achieve cure or prolonged survival if the tumor seems resectable [2, 12, 13]. On the other hand, the role of perioperative chemotherapy is still controversial [13, 14]. According to recent data, perioperative chemotherapy does not improve overall survival. The only independent factor associated with better survival is curative resection with a microscopically negative margin [15]. There is evidence of higher rate of nodal involvement in primary pulmonary sarcomas than in case of extremity soft tissue sarcomas. Therefore, the patients with a primary pulmonary sarcoma have a markedly worse prognosis [16]. Considering this evidence, we decided not to treat the patient with neoadjuvant chemotherapy. After upfront radical surgery with extensive mediastinal lymphadenectomy, which showed clear margins and no nodal involvement, we decided not to give adjuvant chemotherapy either. A close follow-up was advised due to relatively high recurrence rates.
The role of adjuvant radiation therapy still remains equivocal. It can provide acceptable local control of some soft tissue sarcomas after surgical resection [17], but there are also published data not in favor of adjuvant radiotherapy [2]. Therefore, there are no strong evidence-based data for radiation therapy to be an integral part of adjuvant treatment of the primary lung sarcoma.
These neoplasms have an aggressive clinical course with a high potential for recurrence and metastasis. In an advanced stage, a combination of chemotherapy or radiotherapy may be used as a palliative approach, although the tumor seems insensitive to both chemotherapy and radiotherapy [3]. The overall median survival is 24 to 48 months according to retrospective reviews of primary pulmonary sarcoma patients with different histological types (mOS 17 months for grade 3 sarcomas) [9, 12]. However, despite the aggressive behavior of pulmonary sarcoma, there are several reports of patients with long-term survival.
During the short follow-up period, our patient developed unexpected peritoneal dissemination, which, to the best of our knowledge, has not been reported as a site of metastatic spread for primary pulmonary sarcoma yet. There has been one case report of cardiac metastasis from an undifferentiated pleomorphic sarcoma of the lung presenting with symptomatic right heart failure described in the literature [18], and treated with surgical resection.
High-risk features in our case were poorly differentiated histology and tumor size; thus, despite radical surgery with completeness of resection, clear margins, and no nodal involvement, the patient passed away in less than a year after diagnosis was made.