Salivary tumours: a clinicopathological study and follow-up of 156 cases

Radiotherapy in epithelial tumors of the parotid gland: case presentation and literature review

A group of 113 patients irradiated for parotid tumor was studied retrospectively. Sixty-two patients were irradiated after superficial parotidectomy or enucleation of a pleomorphic adenoma. None of them had a recurrence after 5-15 years. Sixteen patients were irradiated postoperatively after surgery for a recurrence of pleomorphic adenoma. Only one of them had developed a recurrent tumor. Thirty-five patients with a malignant parotid tumor were treated by irradiation, 22 after surgery and 13 after biopsy only. Patients with a low malignancy tumor (10/11) and adenoid cystic carcinoma (6/12) responded better than patients with a high malignancy carcinoma (2/12). A tumor larger than 4 cm, facial nerve palsy, lymph node metastasis, and inoperability indicate a poor prognosis. With high dose radiotherapy it is possible to treat inoperable tumors successfully. Adenoid cystic carcinomas can respond well to irradiation alone.

Enucleated parotid tumours

Five pleomorphic, one monomorphic adenoma and one acinic cell lower pole parotid tumours were thought to be lymph nodes and enucleated. Wide excision of the operative site within 2 months revealed microscopic recurrence in three cases. Three carcinomas were enucleated and two had recurred rapidly. It is suggested that such cases of inadvertent enucleation should undergo wide resection of the operative site with nerve dissection.

Management of pleomorphic adenoma of the parotid

A series of 336 parotidectomies, carried out for benign disease has been followed for up to 20 years. One hundred and thirty primary pleomorphic adenomas were treated by wide excision of the tumour after identification of the facial nerve. Recurrence occurred in only one patient and, although 20 patients (15 per cent) experienced some degree of facial nerve weakness postoperatively, there was only one case of permanent weakness.

The prognosis of specific types of salivary gland tumors

The relative rarity of salivary gland cancers means that there are few follow-up studies based on substantial numbers on which estimates of prognosis of the individual histologic subtypes can be based. In an attempt to overcome this problem 106 reports of follow-up studies were examined. For 52 studies a statistical method was devised to calculate 5-year and 10-year survival rates in uniform fashion. Fifty-four reports, however, had to be discarded either because of inadequacy of the data provided or because certain data essential for statistical analysis was lacking. Sufficient data was available for the estimation of survival rates for 2298 malignant salivary gland tumors of four histologic types. The overall 5-year and 10-year survival rates were found to be as follows: acinic cell carcinoma 82% and 68%, respectively; mucoepidermoid carcinoma 71% and 50%, respectively; adenoid cystic carcinoma 62% and 39%, respectively; malignant mixed tumor 56% and 31%, respectively. Since the great majority (over 70%) of salivary gland tumors are pleomorphic adenomas, and also since complete excision of these tumors presents considerable difficulties, their recurrence-free rate was also estimated and found to be 96.6% after 5 years and 93.2% after 10 years.

Histopathologic studies on carcinoma in pleomorphic adenoma of the parotid gland

Five-hundred-eighteen cases of primary epithelial tumors of the parotid gland were examined. The incidence of carcinomas in pleomorphic adenoma was 9.3% (48 cases). In addition to cellular atypism, the following histological findings were thought to be important criteria for the diagnosis of carcinomas: (1) capsular invasion, (2) infiltration into adjacent organs, (3) proliferation of atypical cells within fibrous tissues and chondroid matrix in the area of pleomorphic adenoma, (4) vascular involvement, and (5) mitotic figures. Pleomorphic adenomas (282 cases) were found predominantly in females (70.8%), at the age of 30 to 49 (48.2%), whereas carcinomas in pleomorphic adenoma were more often found in males (70.8%) and at the ages over 50 (43.8%). Histologic types were composed mostly of undifferentiated carcinoma (56.2%) and adenocarcinoma (37.5%). The prognosis of the carcinomas, especially the undifferentiated type, was generally poor; about 45% of the cases either experienced recurrence or died within five years. Electron microscopy on this undifferentiated carcinoma revealed characteristic filamentous structure in the carcinoma cells, resembling that observed in myoepithelial cells. It was assumed that the undifferentiated carcinoma cells were of myoepithelial origin.

The management of parotid neoplasms

In recent years, the management of parotid gland neoplasms has changed considerably, to include a more aggressive surgical approach and multimodality therapy. An organized approach to surgical management and the rationale for postoperative irradiation for selected tumors are presented. A review of several studies supporting the efficacy of postoperative irradiation is included. The principles of palliative management of adenoidcystic carcinoma are unlike those for most other malignancies, and include repeated use of limited procedures to control local and regional disease over extended periods of time, and delayed treatment of distant disease until the patient becomes symptomatic.

Simple enucleation and radiotherapy in the treatment of the pleomorphic salivary adenoma of the parotid gland

A series of 76 patients with a primary pleomorphic salivary adenoma treated by simple extracapsular enucleation and high energy radiation between 1963 and 1976 is presented. Analysis of the results has shown a very low incidence of complications with only minimal cosmetic deformity. Of the 76 patients, only 5 have been lost to follow-up, 3 patients have died of causes unrelated to the tumour and only 1 patient has developed a recurrence. Further local excision in this patient showed the histological appearances of adenocarcinoma.

[Morphology of salivary gland diseases]

The human salivary glands represent a functional system with manifold responsibilities and interactions to the organism. The major and minor salivary glands show a common construction schedule consisting of an acinar functional system for the production of an enzyme- and mucin-containing primary saliva and a ductal functional system with manifold secretory, resorptive and regulatory responsibilities for the transport and the definitive composition of the saliva. The cyclic AMP and calcium iones localized in the glandular acini have an exceptional importance for the course of the secretory process. The neurohormonal control of the salivary secretion results by adrenergic and cholinergic transmitter substances. Moreover the secretory process shows a daily cycle combined with morphological alterations of the glandular cells (so called circadian structures). The fluid secretion of the salivary duct system (the output of sodium-, potassium- and chlorine-iones) represents an active energy-consumed transport process which will be regulated by several factors (autonomic nervous system, quantity of perfusion, hydrostatic pressure in the blood capillaries, transepithelial active transport by ATP-consumed pump systems). The striated ducts are the functional most important sector of the duct system for a rapid fluid- and electrolyte excretion. The terminal axons of the postganglionic sympathic and parasympathic neurits are characterized by spindle-shaped enlargements (varicosities) which contain neurosecretory granules. In the region of the acinar and intercalated duct cells a direct synaptic contact exists for the stimulation transmission, in the course of which the terminal axon contacts immediately with the effector cell by penetration of the basement membrane. The salivary glands form a part of the stabil tissues with reversible postmitotic cells in regard of the tissue regeneration. Under pathological conditions (inflammations, impediment of secretion fluid, radiation effects etc.) metaplasias and proliferations of the duct system arise with development of indifferent duct formations analogous to the type of an embryonal salivary gland. The terminal zone between intercalated and striated ducts represents an indifferent zone with large regeneratory potency. A special behaviour shows the myoepithelial cells which are developed as well to the outside of primitive embryonic duct buds as differentiated intercalated and striated ducts. Morphologically three types of diseases can be classified in the salivary glands: sialadenosis, sialadenitis and tumours.(ABSTRACT TRUNCATED AT 400 WORDS)