Gallbladder ICPN : Differential Diagnosis

Comments:
Differential Diagnosis of Intracholecystic Papillary-Tubular Neoplasm (ICPN):

ICPN vs Flat Dysplasia: Non-tumoral flat dysplasia may show papillary and/or tubular architecture at microscopic level. Some of the papillae may even be tall and exuberant; however, dysplasia does not form a grossly-recognizable mass. Here is an example of dysplasia with papillary architecture.

ICPN vs ICPN with Invasive Carcinoma: It is critical to rule out invasive component in ICPNs. Artifactual distortion and tangential sectioning can make this challenging. When glands are present underneath surface papillary/polypoid component, features favoring invasive carcinoma include: wider separation between glandular units, irregular glandular contours, paradoxical maturation (cytologic differences between surface and deeper glands), foamy glands and cell clusters within clefts and gland lumens. This is an example of ICPN with invasive component. Many of the features described above are seen here. (differential diagnosis continues in the next image)