TTF1 and thymic neuroendocrine carcinoma: Recently, Weissferdt et al. in a study including 25 cases of pulmonary NETs and 25 cases of thymic NETs, concluded that PAX8+/TTF-1− immunophenotype appears to be more common in thymic neuroendocrine carcinomas, whereas the reverse (PAX8-/TTF-1+) is true for most pulmonary neuroendocrine carcinomas [2].