Anterior mediastinal masses: utility of transthoracic needle biopsy

The results of 143 transthoracic needle biopsies (TNBs) in 126 patients with anterior mediastinal masses were compared with the final diagnosis, which was proved with pathologic study (n = 95) or clinicoradiologic methods (n = 31). In the 26 patients with lymphoma, the sensitivity of TNB was 42%; the specificity, 96%. In the 15 patients with Hodgkin disease, the sensitivity was 20%. In the 28 patients with thymoma, the sensitivity was 71%; the specificity, 94%. In the 11 patients with germ cell tumors, the sensitivity was 91%; specificity, 98%. The sensitivity in the 33 patients with metastatic disease was 70%; specificity, 100%. The cytologic specimens were examined with light microscopy and the Papanicolaou method only, a limitation that explains the difficulty in differentiating lymphoma from thymoma and that can now be overcome with immunohistochemical study. TNB of anterior mediastinal masses is useful in metastatic disease and germ cell tumors. Lymphoma and thymoma are less reliably diagnosed unless immunohistochemical cytologic methods are applied.