Distinguishing Benign Mediastinal Masses from Malignancy in a Histoplasmosis-Endemic Region

Abstract

To describe the characteristics of benign and malignant mediastinal masses, which may predict their etiology and facilitate the safe and timely management of patients, especially those residing in histoplasmosis-endemic regions. We conducted a retrospective review of the health records of 131 patients aged <19 years who were referred to 2 tertiary care children's hospitals between 2005 and 2010 for evaluation of mediastinal masses. Most patients (79%) had benign masses, including 98 with confirmed or suspected histoplasmosis. Overall, compared with patients with malignant masses, patients with benign masses were younger and more likely to be African American, to complain of cough, and to have pulmonary nodules by chest computed tomography. In addition, patients with malignant disease were more likely to complain of malaise and to have neck swelling, abnormal extrathoracic lymphadenopathy, lymphopenia, anterior mediastinal involvement, and/or pleural effusion. Positive histoplasmosis serologic tests were specific but insensitive for a benign etiology. No single clinical, laboratory, or radiologic feature was sufficiently sensitive and specific for distinguishing between benign and malignant masses; however, the presence of lymphopenia, anterior mediastinal involvement, or enlarged cervical lymph nodes on computed tomography had a sensitivity of 93%, specificity of 95%, positive predictive value of 86%, and negative predictive value of 97% for cancer. Sixty-four patients (49%) underwent invasive testing, including 37 (36%) of those with benign masses. Patients in this series who had involvement of the anterior mediastinum, lymphopenia, or enlarged cervical lymph nodes had a high likelihood of cancer. Expectant management of patients lacking these characteristics may be safe and reduce unnecessary invasive testing.