There is continued controversy over the extent of parotidectomy required for removal of a benign pleomorphic adenoma from the parotid gland. Currently, consensus exists that the integrity of the facial nerve must be preserved when the tumour is totally removed.

As a result of experience gained in the first half of the twentieth century, it was recommended that superficial parotidectomy with facial nerve dissection should be the minimal biopsy for pleomorphic adenoma. Since that time, however, research has indicated that partial parotidectomy or extracapsular dissection of benign pleomorphic adenoma can be accomplished with preservation of the facial nerve without an increase in tumour recurrence. Partial parotidectomy or extracapsular dissection results in impaired cosmetic results and a lower incidence of Frey's syndrome, and thus may be the preferred approach when undertaken by experienced surgeons.

Objective: The aim of this study was to identify the distribution of parotid tumours within the gland in relation to the facial nerve branches. Documentation revealing such a relationship has not been reported previously.

Method: A prospective study involving 111 patients was carried out over a period of 18 years in a specialist otolaryngology unit within a district general hospital. The relationship of the facial nerve to the tumour was graded into six types. The grading system was then employed to categorize each case.

Results: More than two-thirds of the tumours were pleomorphic adenomas. The majority of these were located in the body and not in the tail of the parotid gland. In 50 per cent of these cases, the tumour was in close association with the two major divisions of the facial nerve. In the case of Warthin's tumours, 47 per cent were located in the tail, below the lower division of the facial nerve.

Pleomorphic adenoma of the parotid gland is common. We report a typical case of a parotid gland swelling which clinically, radiologically and cytologically represented a pleomorphic adenoma. Only following surgical excision and histological examination however, was the true diagnosis of ancient schwannoma made.

Benign peripheral nerve sheath tumours should always be considered in the differential diagnosis of parotid gland tumours.

Pleomorphic adenoma is the most common tumour to arise in the parotid gland. Diagnosis becomes difficult when such a tumour undergoes degeneration and presents with unusual findings. This can lead to erroneous decisions concerning treatment. We present two patients with pleomorphic adenoma of the parotid gland with cystic degeneration, describe the pathological findings and discuss some pitfalls in diagnosis and treatment. Both patients recovered uneventfully after surgery.

A case of Hodgkin's disease presenting as a second primary malignancy in a patient admitted eight years previously for total parotidectomy for an adenoid cystic carcinoma is reported.