SEER Training Modules

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.

The majority of head and neck malignancies (90-95%) are squamous cell cancers (M-807_3).

Subcategories of squamous cell carcinoma include:

  • Lymphoepithelioma (Schminke tumor) (also considered to be anaplastic squamous carcinoma)
  • Keratinizing and non-keratinizing

Histologies for thyroid cancer:

  • Papillary adenocarcinoma (1-2%)
  • Papillary-follicular adenocarcinoma (60%)
  • Follicular adenocarcinoma (20%)
  • Oxyphilic adenocarinoma
  • Undifferentiated (anaplastic) carcinoma (small cell or giant cell carcinoma) (10-15%)
  • Medullary carcinoma (5-6%)

Other Histologies


Lymphomas, adenocarcinoma, adenoid cystic carcinoma, melanoma


Adenocarcinoma (minor salivary glands), lymphoma


Minor salivary gland tumors


Fibrosarcoma, chondrosarcoma, paraganglioma, rhabdomyosarcoma

Salivary glands

Acinic cell tumors, mucoepidermoid carcinoma, adenocarcinoma, malignant mixed tumors, and adenoid cystic carcinoma

Paranasal sinuses and nasal cavity

Esthesioneuroepithelioma, chondro- and osteosarcomas, soft tissue sarcomas, melanoma and lymphoma

Thyroid gland

Sarcomas, lymphomas, epidermoid carcinoma, and teratoma

Synonyms for in situ carcinoma:

(Adeno)carcinoma is 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

Key words:


A white patch on the mucosa of the oral cavity that does not rub off and cannot be characterized as any other disease. Leukoplakia could be an early invasive lesion, hyperkeratosis, lichen planus, or another benign disease.


Red, velvety plaque arising on the mucosa of the oral cavity that cannot be identified as any other condition. Erythroplakia is one of the earliest signs of oral cavity cancer.