Morphology (Histology)

Morphology in ICD-O-3 is a four-digit code that records the histologic type of a neoplasm, reflecting the cell of origin and tissue pattern observed under the microscope. It may be followed by a slash and a single-digit behavior code indicating whether the tumor is benign, in situ, malignant or uncertain, providing a standardized way to capture tumor histology across clinical and research settings.