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PA23.9 | GI Morphology — Practical — SDL Guide (Part 3)

Distinguishing Benign from Malignant Ulcer — Micro Criteria

Side-by-side histology diagram comparing benign peptic ulcer edge with uniform reactive non-invasive epithelium and malignant gastric ulcer edge with atypical invasive glands and desmoplasia. — **Panel A:** Benign peptic ulcer edge with four-zone ulcer floor, uniform reactive hyperplastic glands, intestinal metaplasia, chronic inflammation, intact muscularis mucosae, no cytological atypia, no invasion, converging folds, and endarteritis obliterans in scar base vessels.. **Panel B:** Malignant gastric ulcer edge with irregular malignant glands, hyperchromatic nuclei, prominent nucleoli, loss of polarity, increased mitoses, stromal desmoplasia, invasion beyond muscularis mucosae into muscularis propria, and possible lymphovascular invasion.. **Bottom strip:** Exam scan point emphasizing medium-power examination of the ulcer margin to identify malignant glands at the edge..

Gross features were covered earlier; now consolidate the microscopic criteria.

Benign peptic ulcer micro:
- Ulceration with the four-zone floor
- Surrounding mucosa shows intestinal metaplasia, hyperplastic glands (reactive), and chronic inflammation — but NO cytological atypia in the glands
- No invasion beyond the muscularis mucosae in the surrounding epithelium
- Vessels with endarteritis obliterans in the scar base

Carcinomatous ulcer micro:
- Irregular malignant glands at the ulcer edge and base (intestinal type) OR signet-ring cells (diffuse type)
- Stromal desmoplasia (reactive fibrous stroma around invasive glands)
- Invasion beyond muscularis mucosae, often into muscularis propria or deeper
- Cytological atypia: hyperchromatic nuclei, prominent nucleoli, loss of polarity, increased mitoses
- Lymphovascular invasion may be present at the edge

Practical tip: In an exam slide of a gastric ulcer, always scan the edge of the ulcer at medium power — malignant glands are found at the ulcer margin, not just in the floor. Benign reactive epithelium at the edge is flat or slightly hyperplastic but nuclei are uniform.

Side-by-side H&E 10x comparison of a benign peptic ulcer edge with uniform reactive epithelium and a malignant gastric ulcer edge with irregular invasive glands and desmoplastic stroma. — **Panel A:** Benign peptic ulcer edge showing reactive epithelium, uniform hyperplastic glands, chronic inflammation, converging mucosal folds, absence of cytological atypia, and no invasion beyond muscularis mucosae.. **Panel B:** Malignant gastric ulcer edge showing irregular invasive malignant glands, nuclear hyperchromasia, loss of polarity, mitotic activity, and desmoplastic stroma..

CLINICAL PEARL

The most important three words in a GI pathology practical report are: site, architecture, cytology. Site tells you the differential. Architecture (glands present or absent? granulomas? transmural or mucosal?) narrows it. Cytology (atypia, signet-ring, keratin pearls, mitoses?) clinches benign vs malignant and specific tumour type. Every slide yields to these three questions in order — do not reverse them.

SELF-CHECK

A student reads a gastric ulcer slide and reports: 'The ulcer edge shows mildly enlarged nuclei but they are uniform and the glands are regular.' The most appropriate interpretation is:

A. Reactive (regenerative) epithelial changes — consistent with benign ulcer

B. High-grade dysplasia requiring repeat biopsy

C. Signet-ring cell carcinoma — must report urgently

D. Intestinal metaplasia with early malignant transformation

Reveal Answer

Answer: A. Reactive (regenerative) epithelial changes — consistent with benign ulcer

Mildly enlarged but uniform nuclei with regular gland architecture at the edge of a peptic ulcer are reactive/regenerative changes — not dysplasia. Regenerating epithelium has increased nucleocytoplasmic ratio and mitotic activity but retains nuclear uniformity, polarity, and orderly gland architecture. High-grade dysplasia requires marked nuclear pleomorphism, loss of polarity, and architectural complexity. Signet-ring carcinoma has solitary cells with mucin vacuoles, not glands. Intestinal metaplasia is a specific goblet-cell change, not what's described here.