<prompt> Histology of benign lesion isWell differentiatedAtypicalHigh mitotic figuresLocally invasive  <response>: CharacteristicsBenignMalignantDifferentiation Well differentiated; structure may be typical of tissue of origin Some lack of differentiation with anaplasia; the structure is often atypicalThe rate of growth Usually progressive slow; may come to a standstill or regress; mitotic figures are rare normal Erratic may be slow to rapid; mitotic figures may be numerous abnormal Local invasion Usually cohesive expansile well-demarcated masses that do not invade or infiltrate surrounding normal tissuesLocally invasive, infiltrating the surrounding normal tissues; sometimes may be seemingly cohesive expansile Metastasis Absent Present; the larger and more differentiated the primary, the more likely are metastases 