Cellular Classification of Lip and Oral Cavity Cancer
Most head and neck cancers are of the squamous cell variety and may be preceded by various precancerous lesions. Minor salivary gland tumors are not uncommon in these sites. Specimens removed from the lesions may show the carcinomas to be noninvasive, in which case the term carcinoma in situ is applied. An invasive carcinoma will be well differentiated, moderately well-differentiated, poorly differentiated or undifferentiated.
Tumor grading is recommended using Broder classification (Tumor Grade [G]):
- G1: well differentiated.
- G2: moderately well differentiated.
- G3: poorly differentiated.
- G4: undifferentiated.
No statistically significant correlation between degree of differentiation and the biologic behavior of the cancer exists; however, vascular invasion is a negative prognostic factor.
Other tumors of glandular epithelium, odontogenic apparatus, lymphoid tissue, soft tissue, and bone and cartilage origin require special consideration and are not included in this section of PDQ. Reference to the World Health Organization nomenclature is recommended.
Because leukoplakia, erythroplakia, and mixed erythroleukoplaia are exclusively clinical terms that have no specific histopathologic connotations,  the term leukoplakia should be used solely as a clinically descriptive term to mean that the observer sees a white patch that does not rub off, the significance of which depends on the histologic findings. Leukoplakia can range from hyperkeratosis to an actual early invasive carcinoma, or it may represent a fungal infection, lichen planus, or other benign oral disease.
- Bansberg SF, Olsen KD, Gaffey TA: High-grade carcinoma of the oral cavity. Otolaryngol Head Neck Surg 100 (1): 41-8, 1989. [PUBMED Abstract]
- Close LG, Brown PM, Vuitch MF, et al.: Microvascular invasion and survival in cancer of the oral cavity and oropharynx. Arch Otolaryngol Head Neck Surg 115 (11): 1304-9, 1989. [PUBMED Abstract]
- Oral cavity and oropharynx. In: Rosai J, ed.: Rosai and Ackerman's Surgical Pathology. Vol. 1. 10th ed. New York, NY: Mosby Elsevier, 2011, pp. 237-264.