Morphology & Grade

ICD-O-3 Morphology Codes

If the diagnostic term in the pathology report is not in the following list, be sure to consult your ICD-O manual.


Squamous cell carcinoma (The majority of cancers in the upper two-thirds of the esophagus are squamous cell carcinoma in nature. Adenocarcinomas, which also arise in the esophagus, are more prevalent in the lower third of the esophagus.)

Adenocarcinoma (in Barrett esophagus)

Key words: Barrett esophagus—gastric mucosa (glandular) continuing into esophagus


Adenocarcinoma (81403; 95% of all gastric cancers; subtypes: ulcerative 70%, polypoid 10%, scirrhous/diffusely spreading/Linitis plastica 10%, superficially spreading 5%)

  • Signet ring adenocarcinoma (84903)
  • Linitis plastica (81423)—complete involvement of the stomach; leathery appearance
  • Krukenberg tumor (84906)—metastatic signet ring carcinoma in the ovaries; most likely from stomach or intestinal primary
  • Lymphoma (many morphology codes)
  • Leiomyosarcoma (88903, 88913, 88963; 1% of all gastric cancers)

Small Intestine

  • Adenocarcinoma (81403)
  • Lymphoma (many morphology codes)
  • Leiomyosarcoma (88903, 88913, 88963)
  • Carcinoids (82403, 82413, 82433, 82443)

Synonyms for in situ carcinoma: (adeno)carcinoma in an adenomatous polyp with no invasion of stalk, confined to epithelium, noninfiltrating, intraepithelial, involvement up to, but not including, the basement membrane, noninvasive, no stromal involvement, papillary noninfiltrating