BDS10019 Salivary Gland Neoplasms (Lecture) PDF

BDS10019 Salivary gland neoplasia Aims: The aim of this lecture is to detail the histopathological aspects of tumours of the minor and major salivary glands Objectives: On completion of this lecture, the student should be able to: Understand the principle histopathological manifestations of com...

BDS10019 Salivary gland neoplasia Aims: The aim of this lecture is to detail the histopathological aspects of tumours of the minor and major salivary glands Objectives: On completion of this lecture, the student should be able to: Understand the principle histopathological manifestations of common benign and malignant tumours of the salivary glands Salivary gland tumors pleomorphic adenoma Warthin tumor mucoepidermoid carcinoma adenoid cystic carcinoma oncocytoma carcinoma ex pleomorphic basal cell adenoma Prevalence of salivary gland tumors according to data reported by WHO 2017 Salivary gland neoplasms Epithelial Benign -Pleomorphic adenoma -Warthin’s tumor Non epithelial Malignant -carcinoam ex pleomorphic -mucoepidermoid carcinoma -Adenoid cystic carcinoma -Benign mesenchymal tumors -sarcomas -lymphomas -metastasis to SG General criteria Benign neoplasms Malignant neoplasms Slowly growing painless No surface ulceration (except in tumors of the palate) or bone invasion Parotid tumors show no facial nerve paralysis Rapidly growing painful No metastasis Ulceration of mucosa and bone invasion Parotid tumors show facial nerve paralysis Undergo metastasis to the regional lymph nodes BENIGN SALIVARY GLAND NEOPLASMS Pleomorphic adenoma (PA) It is a benign tumor with variable cytomorphological and architectural manifestations [i.e: variety of histological appearances]  It is the most common salivary gland tumor in both children and adults  For diagnosis of PA TWO components should be identified: epithelial and myoepithelial Pleomorphic adenoma Clinical Features:  It occurs at any age with slight female predilection  Parotid gland is most common site followed by the palate and submandibular gland.  Painless  Slowly growing mass  Solitary tumor but metachronous (not existing in same time) or synchronous (existing in same time) tumors may occur Pleomorphic adenoma Clinical Features: In case of malignant transformation:  sudden rapid growth  surface ulceration  facial paralysis Macroscopic features  Usually single, firm, movable  Solid in cut section Pleomorphic adenoma Histopathologic features: A pleomorphic adenoma is surrounded by a capsule of varying thickness and completeness. [what is the clinical significance?] Normal salivary gland tissue Connective tissue capsule Tumor tissue Pleomorphic adenoma Histopathologic features: Tumor consists of Epithelial elements Myoepithelial elements Pleomorphic adenoma Histopathologic features: The epithelial element is arranged in: a-tubular structures (resembling normal ducts) b- Solid sheets or strands Pleomorphic adenoma Histopathologic features: The myoepithelial element Spindle myoepithelial cells stream from the ductal elements into chondromyxoid stroma Pleomorphic adenoma Histopathologic features: The myoepithelial element Cells may undergo squamous metaplasia with keratin production Cells may be arranged in a way showing lipomatous or osseous appearances Pleomorphic adenoma Treatment & prognosis Parotidectomy is recommended rather than enucleation to avoid recurrence WHY? Because the capsule is incomplete SO some neoplastic cells may infiltrate through it to the surrounding tissue causing difficulty in complete removal of the tumor and consequently, increase recurrence rate Increased risk of malignant transformation occur with Multiple recurrences Deep parotid lobe location Older patient age Metastasizing pleomorphic adenoma This tumor is histologically indistinguishable from PA but produces secondary tumors in distant metastasis To date, only 81 cases were described, most of them developed metastasis after multiple local recurrences Most common distant sites are bone, followed by head and neck and lung Prognosis is usually good Warthin tumor (Papillary cystadenoma lymphomatosum) Warthin tumor is the 2nd most common salivary gland tumor Definition: It is composed of oncoytic epithelial cells lining ductal, papillary, cystic structures in lymphoid stroma These tumors are linked to cigarette smoking Warthin tumor (Papillary cystadenoma lymphomatosum) How does the lymphoid tissue become in contact with salivary gland tissue in parotid gland? Late encapsulation of parotid gland during embryonic life results in enclosing small lymph nodes within the parotid gland. OR enclosing salivary ducts and acini in lymph nodes outside the parotid capsule. Warthin tumor (Papillary cystadenoma lymphomatosum) Clinical features Usually occur in 6th to 7th decades. It develops males >females. Usually locates in the inferior pole of parotid gland It is a painless, slowly growing Fluctuant swelling It may occur multifocally in the same or bilateral glands Warthin tumor (Papillary cystadenoma lymphomatosum) Macroscopic features Well circumscribed masses The cut section is solid with multiple cysts with papillary projections Warthin tumor (Papillary cystadenoma lymphomatosum) Histopathologic features It is composed of multiple papillary cystic spaces lined by:  Oncocytic epithelial cells [cytoplasm contains numerous eosinophilic granular (yellow arrow) Lymphoid stroma with germinal centers (red arrow) Warthin tumor (Papillary cystadenoma lymphomatosum) Histopathologic features The epithelial component is formed of a- The outer cuboidal cells b- The inner columnar (with oncocytic appearance eosinophilic granular cytoplasm). i.e: Warthin tumor (Papillary cystadenoma lymphomatosum) Treatment & prognosis Complete surgical excision Local recurrence rate is low Malignant transformation is extremely rare MALIGNANT SALIVARY GLAND NEOPLASMS Carcinoma ex-pleomorphic adenoma This is a salivary gland malignancy developing from primary or recurrent pleomorphic adenoma Clinical features  It usually occurs in 6th or 7th decades, women > men Parotid is the most common site It often presents as a sudden rapid growth of painful mass within a pre-existing longstanding mass Carcinoma ex-pleomorphic adenoma Clinical features  The growth may become hard and fixed to the surrounding tissues  May show ulceration of the overlying skin or mucous membrane May show facial paralysis Carcinoma ex-pleomorphic adenoma Histopathologic features  carcinoma ex-pleomorphic adenoma shouldn’t be considered as a standalone diagnosis because the type and extent of carcinoma component impact the management of patients. Most tumors show the appearance of: Intracapsular carcinoma confined within pleomorphic adenoma Salivary duct carcinoma or myoepithelial carcinoma Carcinoma ex-pleomorphic adenoma Treatment & prognosis  carcinoma ex-pleomorphic adenoma is an aggressive malignancy that commonly undergo local and distant metastasis Most favorable outcome is seen in Intracapsular carcinoma Mucoepidermoid carcinoma (MEC) Most common salivary gland malignancy in children and adults Clinical Features:  Parotid gland is most common site followed by the palate and submandibular gland.  Primary intra-osseous (central) MEC is rare [may arise from the wall of a dentigerous cyst]  Tumors of the palate may show mucosal ulceration, destroy neighbouring bone and cause loosening of teeth Mucoepidermoid carcinoma (MEC) Macroscopic features  MEC may be soft or firm  Circumscribed or infiltrative  Usually has cystic component Mucoepidermoid carcinoma (MEC) Histopathologic features MEC is composed of 3 types of cells:  Mucinous (mucin producing) cells [black arrows]  Squamoid (squamous like) cells [yellow arrows]  intermediate cells  These cells are arranged in cystic and solid patterns  There are low and high grades as well as intermediate grade tumors which show features between both of them. Mucoepidermoid carcinoma (MEC) Low grade MEC High grade MEC Copyright © 2003, Elsevier Science (USA). All rights reserved. Clinically Cells Cyst formation Cellular atypia & necrosis Low grade (good prognosis) High grade (fair prognosis) less aggressive painless mass,