Clinical significance of the tumour capsule in the treatment of parotid pleomorphic adenomas

The propensity of pleomorphic adenomas to recur is generally attributed to the biological nature of the tumour, and surgery close to the capsule is perceived as undesirable. At the Christie Hospital, Manchester, between 1947 and 1992, 475 tumours arising within the superficial portion of the parotid gland were treated by two surgical techniques: extracapsular dissection (380 patients) and superficial parotidectomy (95). Recurrence rates were 2 per cent in each group (median follow-up 12.5 years). Contact of the tumour with the facial nerve was recorded in 51 per cent of patients. There was no difference between the treatment groups in the incidence of permanent facial nerve injury (2 versus 1 per cent respectively). This study demonstrates that dissection in close proximity to the tumour is possible without inducing recurrence and that in practice the microinvasion of the capsule by tumour buds has limited clinical significance.