It's transitional cell carcinoma, which smoking is a common risk factor for; it can involve the renal pelvis/calyces. The histo image shows the papillary nature of the tumor (however it can also be flat or nodular according to Pathoma).

Also known as urothelial carcinoma. Most common tumor of urinary tract system (can occur in renal calyces, renal pelvis, ureters, and bladder). Can be suggested by painless hematuria (no casts).

Etiology → Cigarette smoking is major risk factor (50-80% of cancers, risk associated with duration and intensity) Also arylamines (2-naphthylamine) and aniline dyes In developing countries, Schistosoma haematobium ova are deposited in bladder wall and cause chronic inflammation, squamous metaplasia, dysplasia; 70% of tumors are squamous cell carcinoma HPV may cause condyloma, squamous dysplasia, squamous cell carcinoma sequence Phenacetin use (usually long term use in younger women, tumors involve upper collecting system) Chronic urinary tract infection and calculi Rarely cyclophosphamide with long term use

SPOLIER ALERT for future readers, the content following may contain subjects seen in other NBMEs

either bladder cancer (unilateral in this case) or transitional cell carcinoma (also uni) are precipitated by smoking inhalant toxic injury. BUT what matters more than the cause is that the reader recognize that this is without a doubt

obstructive hydronephrosis with dilated pelvicalyceal system and cortex of kidney showing atrophy and thinning.

Assuming that the pt lost blood from the MVA - this would further enhance the renal ischemia (PCT and ascending LOH are both very sensitive to ischemic conditions 30 minutes of blood loss is enough to exacerbate the already ischemic conditions.

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This is LITERALLY the same photo they used to describe the 4-year-old boy with diffuse cortical necrosis from NBME 18. Can someone explain what's going on here