Schneiderian papillomas

The ectodermally derived ciliated respiratory mucosa that lines the sinonasal tract, so-called Schneiderian membrane, gives rise to three morphologically distinct papillomas. These are referred to individually as the fungiform(BOTTOM L), inverted(TOP), and oncocytic papillomas(BOTTOM R) or, collectively, as Schneiderian papillomas.
These benign lesions were named in honor of C. Victor Schneider who, in the 1600s, demonstrated that nasal mucosa produces catarrh and not CSF and identified its origin from the ectoderm.
Unlike the rest of the upper respiratory tract mucosa, the sinonasal mucosa is ectodermal in origin, derived originally from the stomodeum (ie, primitive mouth) in the fourth week of gestation. Sinonasal mucosa is continuous with the mucosal lining of the nasopharynx, which is of endodermal origin but is of identical histology.