AB047. PS02.11: Thymic mesenchymal neoplasia: a single institution experience

Background: Thymic mesenchymal (TM) neoplasia is a group of rare disease, constituting less than 10% of all mediastinal neoplasms. Our aim was to evaluate whether radical surgical resection is an effective treatment for TM.

Methods: Patients submitted to surgical resection with curative intention for malignant TM were included in this study. Patients with a benign mediastinal mesenchymal lesion were excluded from the analysis. The influences of clinical features and biological aspects as age, sex, tumor size, tumor location, histotype, grade, and therapy on the prognosis of the patients were analysed. Overall survival (OS) was the primary endpoint. Secondary endpoints were hystotype-related survival, progression free survival (PFS) in resection status R0.

Results: According to the selection criteria, all patients (10) undergoing thoracic surgery procedures in our Department between January 01 2005, and January 01 2017, for mesenchymal thymic neoplasia were eligible for this study. Fluorodeoxyglucose-labeled positron emission tomography (FDG PET) was performed in all patients. Nuclear Magnetic Resonance (NMR) was performed in 7 patients (70%). In all cases preoperative biopsy was performed in order to exclude a hematological disease. Seven patients were male (70%) and mean age was 60 years (range, 26–86 years). Mean tumor size was 8.33 cm (range, 1.3–19.00 cm). The vast majority [8] of the patient were asymptomatic at the diagnosis, while in two cases mediastinal syndrome was observed. No patient had Myasthenia gravis. Thymoliposarcoma was the commonest histological subtypes (4–40%), followed by leiomyosarcoma (2–20%), synovial sarcoma (1–10%), spindle cell sarcoma (1–10%), angiosarcoma (1–10%) and thymic solitary malignant fibrous tumor (1–10%). Surgical approaches were total median sternotomy [6], cervicosternotomy [2], anterolateral thoracotomy [1]. Resection status R0 was gained in 6 cases (70%). Three patients (30%) performed neoadjuvant chemotherapy. PET status was no significantly associated with malignant attitude. At the end of the study period, 7 patients died. The overall survival rate at 5 years was 30% poor disease-free survival was observed in leiomyosarcoma, spindle cell sarcoma and synovial sarcoma. The R0 status was a favorable prognostic factor for OS.

Conclusions: The biological and clinical behaviour of this heterogeneous group of neoplasia was similar to B3-C thymoma. Our results indicated that stage, grade, histological type and the radical surgery are strong predictive factors. Finally, adjuvant chemotherapy seems to have a minor role on survival.

Keywords: Radical surgery; overall survival (OS); thymic mesenchymal neoplasia