Surgical Pathology of Organ Systems
Overview
The largest scored domain. It tests whether you can commit to a defensible diagnosis and produce a complete, guideline-concordant synoptic report for resections and biopsies across breast, GI, lung, genitourinary, thyroid, head and neck, and soft tissue.
Core rules
- Every cancer report answers: site, WHO histologic type, grade, size, margin status and distance, lymphovascular invasion, perineural invasion, node count and positive count, and pT/pN.
- Breast: Nottingham grade uses tubule formation, nuclear pleomorphism and mitotic count; ER/PR reported as percentage plus intensity; HER2 by IHC 0/1+/2+/3+ with ISH reflex for 2+.
- Prostate: Gleason patterns map to ISUP Grade Groups 1–5; report percentage pattern 4/5, extraprostatic extension, seminal vesicle invasion and margin status.
- Colorectal: pT1 submucosa, pT2 muscularis propria, pT3 subserosa/pericolic fat, pT4a visceral peritoneum, pT4b other organs; MSI/dMMR testing is recommended for all colorectal carcinomas.
- Lung: adenocarcinoma versus squamous is resolved with TTF-1/Napsin A versus p40/p63.
Worked example
A sigmoid colectomy shows adenocarcinoma invading through muscularis propria into pericolic adipose tissue without reaching the serosal surface; 2 of 14 nodes are positive. Reasoning: invasion into subserosal fat is pT3; pT4a requires tumor on the visceral peritoneal surface, which is absent. Node status gives N1b (two to three positive nodes), so the final stage is pT3 pN1b. Reporting pT4a here would upstage and misdirect adjuvant discussion.
Traps
Equating "through the bowel wall" with pT4. Omitting lymphovascular invasion because it does not change pT. Reporting HER2 2+ without ISH. Using "moderately differentiated" in place of a formal grade.