Marginally excised parotid pleomorphic salivary adenomas: risk factors for recurrence and management. A 12.5-year mean follow-up study of histologically marginal excisions

The aim of the study was to identify recurrence risk factors in surgically excised parotid pleomorphic salivary adenomas. We reviewed the case histories and histological findings for all cases of marginal or inadequate excision of pleomorphic salivary adenomas at the Royal Hallamshire Hospital, Sheffield, UK, between 1980 and 1995. A total of 83 cases with complete records were identified, with a mean follow-up period of 12.5 years. The histological slides were reviewed in each case. The overall recurrence rate was 6.0%. Where tumour was present at the margin, recurrence occurred in 17.6% of cases. However, cases conventionally regarded as marginally excised and likely to recur (tissue margin<1 mm) showed recurrence in only 1.8% of cases. Intraoperative capsular rupture, microscopic capsular invasion by tumour and several other surgical factors were not predictive of recurrence. Adequate excision of pleomorphic salivary adenomas, in the sense of minimal recurrence risk, does not require more than a fraction of a millimetre of surrounding tissue. Only pleomorphic salivary adenomas with tumour actually at the excision margin require prolonged follow-up or consideration of radiotherapy. Provided that the tumour can be removed intact, the surgical approach for pleomorphic salivary adenomas should be guided by the need to preserve vital structures rather than by an attempt to remove a cuff of normal tissue with the tumour.