Utilizing neuroendocrine tumor samples, we found that the frequency as well as the average intensity of the expression of PAX5 increased from pulmonary carcinoid (9%, moderate and strong PAX5 expression, n=44), to large-cell neuroendocrine carcinoma (LCNC, 27%, n=11) to SCLC (33%, n=76).
Nuclear PAX5 staining was observed in 16 (42%) cases in total, in 46% (11/24) of large cell neuroendocrine carcinoma, 67% (4/6) of small cell neuroendocrine carcinoma, and 13% (1/8) of mixed adenoneuroendocrine carcinoma, with diffuse (8), patchy (4), or focal (4) staining.