High Risk Histologic Features are defined in AJCC 8 Chapter 15 to include the terms "poor differentiation, desmoplasia, sarcomatoid differentiation, undifferentiated." High risk histologic features are a prognostic factor for cutaneous cell carcinomas of the head and neck.

High Risk Histologic Features is a Registry Data Collection Variable in AJCC. It was previously collected as Skin, CS SSF # 12.

0	No high risk histologic features
1	Desmoplasia
2	Poor differentiation (grade 3)
3	Sarcomatoid differentiation
4	Undifferentiated (grade 4)
5	Multiple high risk histologic features
6	Histologic features, NOS (type of high risk histologic feature not specified)
8	Not applicable: Information not collected for this case (If this information is required by your standard setter, use of code 8 may result in an edit error)
9	Not documented in medical record High risk histologic features not assessed or unknown if assessed

Each Site-Specific Data Item (SSDI) applies only to selected primary sites, histologies, and years of diagnosis. Depending on applicability and standard-setter requirements, SSDIs may be left blank.