Ultrastructural assessment of adenoid cystic carcinoma with emphasis on tumour infiltration periphery

Abstract

Summary Background There is a wide variety of morphological and clinical types of tumours of the salivary glands. Almost 30 histological types of these neoplasms are known. Adenoid cystic carcinoma is a rarely occurring malignant epithelial neoplasm. It occurs in major salivary glands, but may also originate in the salivary glands of the respiratory tract. Aim The aim of the present study was the ultrastructural assessment of the infiltration periphery of different histological types of adenoid cystic carcinoma of the salivary glands. Materials and Methods Tissue samples from patients with adenoid cystic carcinoma of the salivary glands were studied. The study group consisted of 30 pts. 21 pts with tumour of parotid, 8 with submandibular and 1 with tumour of sublingual salivary glands. All patients were surgically treated and undergone supplementary treatment using radiotherapy in the Greater Poland Cancer Centre. Assessment of tissue samples was performed using morphological diagnoses and ultrastructural evaluation. Results Ultrastructural electron microscopy assessment of adenoid cystic carcinoma revealed differentiation of the tumour cells towards ductal salivary, myoepithelial and pluripotential cells. Epithelial cells showed an increased nucleus-cytoplasm ratio, and their nucleoli were characteristic for actively proliferating cells. The analysis showed histological and structural differences between the central and peripheral parts of the tumour. Conclusions The ultrastructural assessment of adenoid cystic carcinoma revealed that the cells in the peripheral parts of the tumour show a lower degree of maturation than the ones in its centre, peripheral stroma contains fewer collagen fibres, and dominant elements at the periphery of the tumour are proteoglycans and glycosaminoglycans, no histoformative features typical of the principal (central) part of the tumour were found at its periphery.