Gallbladder ICPN : Differential Diagnosis

Comments:
Differential Diagnosis of Intracholecystic Papillary-Tubular Neoplasm (ICPN) (continued from the previous image):

ICPN extending into Rokitansky-Aschoff (RA) sinuses vs ICPN with Invasive Carcinoma: In ICPN, extension of dysplasia into RA sinuses can mimic invasive carcinoma. RA sinuses are often surrounded by a loose band of stroma which may be mistaken for desmoplasia. It is worth remembering that most gallbladder carcinomas don't show significant desmoplasia. Features favoring RA sinuses: large flask shaped or elongated glands; glands oriented with longitudinal axis perpendicular to the surface; glands usually (but not always) connected to the overlying surface epithelium; presence of residual normal epithelium with a sharp transition from benign to dysplastic areas.

In this image, the gland on the left is lined by dysplastic epithelium with nuclear hyperchromasia and pseudostratification. The gland on the right is relatively spared (note the single layer of simple columnar epithelium on the right edge).