COW-2019-15

1. d

Invasive urothelial carcinoma, microcystic variant

The pictures show microcystic urothelial formations of variable size and shape growing in a haphazard fashion and infiltrating the bladder wall and the muscularis propria. Also present is a component of invasive urothelial carcinoma, usual type. The cysts composing the microcystic variant are typically lined by single or stratified urothelial cells which may also be flattened. Importantly, the cells are overall bland and therefore the main differential diagnosis is cystitis cystica at glandularis (CCCG), a distinction which can prove to be challenging in superficial biopsy specimens. CCCG tends to be organized and superficial; does not involve the muscularis propria and lacks the size variation which typifies microcystic carcinoma. Microcystic carcinoma often coexists with the nested variant of urothelial carcinoma and does not show frank mucin production or true gland formation of adenocarcinoma A component of usual urothelial carcinoma is also seen approximately 40% of cases. Stage-by-stage, there are no survival differences between this variant and usual urothelial carcinoma.

Variants and new entities of bladder cancer. Lopez-Beltran A, Henriques V, Montironi R, Cimadamore A, Raspollini MR, Cheng L.
Histopathology. 2019;74(1):77-96.

Microcystic urothelial carcinoma: morphology, immunohistochemistry and clinical behaviour. Lopez Beltran A, Montironi R, Cheng L.
Histopathology. 2014;64(6):872-9.

Fadi Brimo
McGill University Health Center
fadi.brimo@mcgill.ca

Bladder

microcystic, urothelial