Patients with primary mediastinal lymphomas frequently present with a residual mass after completion of first-line therapy. Although a positron emission tomography scan is usually recommended, it fails to distinguish between persistent lymphoma and inflammation. Although percutaneous biopsy may have a high diagnostic yield for the initial diagnosis of mediastinal lymphomas, this biopsy has poor accuracy for detecting persistent disease in a residual mass given the heterogeneity of these residual masses. Because persistent disease has important therapeutic implications, we evaluated the role of operative biopsy in detecting lymphoma in the residual mass.Methods:
Between 2009 and 2015, consecutive patients (n=77) undergoing tissue biopsy for initial diagnosis as well as for a positron emission tomography-positive residual mass were included. Tissue biopsy for a residual mass was repeated until frozen section was diagnostic or at least the mass on the ipsilateral hemi-mediastinum was resected.Results:
Of the initial 77 patients, 34 underwent operative restaging for a residual mass after chemotherapy, while 43 had a complete response. In these 34 patients, operative biopsy revealed the presence of lymphoma in 53%, predominantly Hodgkin's disease and diffuse large B-cell lymphoma. There was no significant difference in tumor volume (51% versus 39%) and a decrease in the positron emission tomography-standardized uptake valuemax (68% vs 60%) in patients with or those without persistent lymphoma. There were no surgical complications and the duration of stay for all patients undergoing thoracoscopy was <24 hours. Residual lymphoma was treated with second-line therapy guided by the pathologic analysis.Conclusion:
A large proportion of patients with residual positron emission tomography-avidity after first-line chemotherapy of mediastinal lymphomas have residual disease that can be detected safely using minimally invasive thoracoscopy.