Change in histological grade in locally recurrent soft tissue sarcomas

Histological examination of locally recurrent soft tissue sarcomas usually reveals an appearance similar to that of the original tumour. Occasionally, however, recurrent sarcomas appear more or less malignant histologically than the initial lesion. The goals of this paper were to identify the frequency with which this phenomenon occurs, factors that predict for a change in grade and to determine if this change is associated with a different prognosis from other patients with local recurrence. From a large sarcoma database, 124 patients with local recurrence were identified. These patients were distributed into groups who had no change in histological grade, increased histological grade or decreased histological grade on local recurrence. Increased grade occurred approximately 20% of the time, whereas decreased grade occurred in 7% of cases. A histological diagnosis of myxofibrosarcoma was predictive of an increase in histological grade on local recurrence. An increase in histological grade with local recurrence was not associated with a poorer survival.