#1: MP/H Rules
Source 1: 2007 MP/H Rules
MP/H Rules/Histology--Bladder: Is urothelial carcinoma, high-grade, predominantly solid type, coded as 8120/3 or 8230/3? See Discussion.
Urinary bladder: Invasive urothelial carcinoma, high-grade, 4.5cm, predominantly solid type, arising in background of carcinoma in-situ, carcinoma grossly extends into perivesical adipose tissue; lymph-vascular invasion is seen.
Assign histology code 8120/3, urothelial carcinoma, NOS. Solid type is not a recognized variant of urothelial tumors and likely represents the appearance of the urothelial cells within the tumor and not a specific histologic type.