This code system http://hl7.org/fhir/v2/0417 defines the following codes:

CodeDisplay
0No tissue expected
1Insufficient Tissue
2Not abnormal
3Abnormal-not categorized
4Mechanical abnormal
5Growth alteration
6Degeneration & necrosis
7Non-acute inflammation
8Non-malignant neoplasm
9Malignant neoplasm
BBasal cell carcinoma
CCarcinoma-unspecified type
GAdditional tissue required