Arnold Maran – Science, Skill and Serendipity in Salivary Gland Disease

Written by Professor Michael Gleeson

There is certainly skill in salivary gland surgery and ENT surgeons are supposed to have it. How much have they contributed to the science of salivary gland surgery, and are good surgical outcomes more the result of serendipity? A lot can be learned by a glance back at history and the mistakes made in the past. Are we still making the same mistakes?

Until the mid 1960’s most salivary gland surgery was undertaken by general surgeons. John Conley, the doyen of salivary gland surgery who made identification of the facial nerve relatively simple, was a general surgeon. Sistrunk in the 1920’s had published large series with dreadful results by today’s standards. Salivary tumours in those days presented late, late enough for malignant transformation to have taken place. For some, Sistrunk’s surgery was revision surgery after ruptured enucleations that had merely resulted in widespread recurrences. In short, there was a significant mortality and huge facial nerve morbidity. The histopathologists were not much better. They had difficulty determining which tumours were benign or had been benign at one stage.

The problem today is that we now know that 80% of parotid salivary tumours are benign. It tempts us to cut corners in terms of diagnostic preparation for surgery and the completeness of a resection with a good margin of healthy tissue. There is often little to distinguish a malignant tumour from a benign one in the very early stages of development. Pain, facial palsy and rapid growth rate may not be evident. Albeit that pre-operative cytology now has a high index of accuracy, a non-diagnostic report does not exclude malignancy and not every surgeon has access to good cytology. Some even rely of scan appearances or reports. Histopathologists also have their problems. Of the 3,300 tumours archived in the British Salivary Gland Panel data, 1276 cases were referred without a tentative diagnosis and in 533 [25.8%] of the remaining 2058 tumours, the referring pathologist admitted that he was unable to make the diagnosis or had made an incorrect one. The sensitivity of the referring pathologists for malignant epithelial tumours was 83.2% and specificity was 94.9%. In other word, they missed 1 in every 6 malignant tumours and wrongly attributed benign status to 1 in every 20 tumours. Furthermore, a number of malignant salivary gland tumours have an extended natural history and mistakes in histopathology only become evident 20 years later.

Are we surgeons perfect? Certainly not. Extra-capsular resection is now advocated by some. Is there really a difference between an extracapsular dissection and an enucleation, especially when made more pertinent if the diagnosis is returned as a malignant tumour? Are our surgical results more by luck than judgement?