Chapter 10. Diseases of Salivary glands. Consists of three paired major S.Gs which are parotid ,submandibular & sublingual. Also countless minor S.Gs found in almost every part of the oral cavity , except the gingival & anterior regions of the hard palate.
Diseases of Salivary glands
Causes of xerostomia
Causes of ptyalism
Suppurative parotitis - pus is leaking from the parotid
Chronic sialadenitis resulting from obstruction. The ducts
contain casts of mucin and neutrophils and are surrounded by a layer of fibrosis. There is severe acinar atrophy and the space previously occupied by acinar cells now contains infiltrates of lymphocytes and plasma cells.
Salivary calculus. This stone has impacted just behind the orifice of the submandibular duct forming a hard nodule. The yellow colour of the stone is visible through the thin mucosa.
Salivary calculus in a duct. To the left is the salivary calculus which has a lamellar structure and an irregular surface. On the surface is a thick layer of microbial flora filling the space between the stone and the epithelial lining. In the surrounding wall there is an infiltrate of
lymphocytes and plasma cells and neutrophils are migrating through the duct epithelium into the lumen.
Mucous retention cyst. Remnants of the minor mucous salivary glands are visible, together with their dilated duct, the epithelium of which is continuous with the epithelial lining of the cyst (above).
Extravasation mucocele. To the left is a cavity of spilt mucin with the remnants of the ruptured duct lining epithelium at its edge. To the right is the associated minor mucous salivary gland. A, saliva and macrophages; B, compressed connective tissue wall; C, minor salivary gland.
Mucous extravasation cyst. The typical presentation at the commonest site: a rounded bluish, translucent cyst in the lower lip.
Ranula. A large bluish, translucent swelling in the floor of the mouth caused by a mucous extravasation or retention cyst.
Extravasation mucocele. Higher power showing the lining of the mucin-filled space. Macrophages are migrating into the mucin and in phagocytosing it develop a foamy or vacuolated cytoplasm.
Sjogren's syndrome. Extensive cervical caries is a frequent complication of dry mouth. In addition to the lack of saliva, patients may attempt to stimulate salivary flow with sweets or chewing gums.
Salivary gland swelling in primary Sjogren's syndrome. The outline of the parotid gland is clearly demarcated.
Sjogren's syndrome. The sialogram shows the typical snowstorm appearance of blobs of contrast medium that have leaked from the duct system. Emptying and clearance of the contrast medium are also much delayed because of the reduced salivary flow.
Sjogren's syndrome. The histological appearance is typical. Dense, well-defined foci of lymphocytes surround the larger ducts in the centre of the lobules. In the area occupied by the lymphocytes there is complete acinar atrophy and a rim of residual salivary parenchyma remains around the periphery of the lobule.
Sjogren's syndrome. In late disease no salivary acini remain and the gland is replaced by a confluent infiltrate of lymphocytes. A few ducts remain and proliferate to form the epimyoepithelial islands. Such
extensive changes sometimes suggest that there has been progression to a low-grade lymphoma.
General clinical features of S.Gs tumours :
Age : adult , sex : female more than male
Site : - intraoral site : palate ( junction between hard & soft palate , most malignant)
- Parotid gland ( mostly benign)
The distribution of salivary gland neoplasms showing the approximate overall frequency of tumours in different sites and the relevant
frequency of benign and malignant tumours by site.
Important histological features of pleomorphic adenomas
Pleomorphic adenoma. The junction of hard and soft palates is a common intraoral site; the tumour usually feels rubbery and lobulated on palpation.
Pleomorphic adenoma. This slowly enlarging lump in the lower pole of the parotid gland is caused by a pleomorphic adenoma but the appearance is not specific and any benign and some low-grade malignant neoplasms could appear the same.
Pleomorphic adenoma. The histological appearances are very varied. In this typical area there are clusters of ducts containing eosinophilic material surrounded by stellate cells lying in a mucinous stroma.
This excised pleomorphic adenoma is 3 cm across and the lobular shape is clearly seen.
Pleomorphic adenoma. In this area there has been maturation of the mucinous stroma to form a cartilage-like material within which there are more cellular islands with ducts
Plemorphic adenoma. In this lesion there is formation of true cartilage which is undergoing calcification.
Pleomorphic adenoma. At the margins of pleomorphic
adenomas there are often extensions of the tumour into and beyond the capsule, rendering enucleation an ineffective treatment.
Warthin's tumour. Tall columnar cells surround lymphoid tissue and line a convoluted cystic space.
Warthin's tumour. At higher power the tall columnar epithelial cells are readily identified and beneath them the lymphoid tissue
Mucoepidermoid carcinoma. At higher power the finely
granular mucous cells are seen to the right with the underlying epidermoid cells to the left.
Mucoepidermoid carcinoma. The mucous cells surround microcysts. Underlying the mucous cells are the epidermoid (squamous) cell
Adenoid cystic carcinoma. There is an ulcerated mass arising from a minor gland in the palate. The clinical appearance would be the same with other malignant salivary neoplasms.
Adenoid cystic carcinoma. The small darkly staining cells of the adenoid cystic carcinoma form cribriform islands with large holes which have been likened, rather inappropriately, to Swiss cheese.
Carcinoma arising in a pleomorphic adenoma. In longstanding pleomorphic adenomas the stroma may become hyalinised, dense and acellular. In such tumours there is a risk of transformation to carcinoma, as shown here by clusters of cells showing cytological atypia
Acinic cell carcinoma. The tumour is composed of granular acinar-type cells, sometimes arranged in acinus-like clusters and sometimes forming irregular sheets. Cytological atypia is uncommon.
Polymorphous low-grade adenocarcinoma. A. Targetoid pattern; B. cribriform area; C. surviving acini inside the tumour; D. papillary cystic area.