WARTHIN’S TUMOR: CLINICAL FEATURES, HISTOPATHOLOGY & TREATMENT
Author: Sanketh DS, MDS
Warthin’s tumor also known as papillary cystadenoma lymphamatosum (PCL) is the 2nd most common benign salivary gland tumor, first described by Warthin in 1929. This lesion has an almost restricted occurrence for the parotid gland, comprising 5-22% of all parotid neoplasms, although it may very rarely occur in the submandibular glands or other minor salivary glands. Though Warthin’s tumor is believed to be a benign tumor, there are studies which suggest that this lesion may not be a true neoplasm.
ETIOLOGY AND PATHOGENESIS
Although the pathogenesis of this lesion is unknown, there are a few theories that have been put forth. The commonly accepted hypothesis suggests that heterotopic salivary gland tissue proliferate within intra-parotid or para-parotid lymph nodes to give rise to the lesion.
Another theory proposes hypersensitivity to be responsible for the tumor formation. It was suggested that striated ductal cells after undergoing a metaplastic change to oncocytic cells, could induce a hypersensitivity reaction, causing lymphocyte infiltration and accumulation in the stroma.
Warthin’s tumor has also been hypothesized to simply be a neoplastic proliferation of parotid ductal epithelium with simultaneous secondary formation of lymphoid tissue.
Etiological factors like smoking and Epstein Barr virus have reported to cause this tumor. Smokers have been estimated to have a 4-8 fold risk of developing Warthin’s tumor. It is thought that the tobacco products could cause metaplasia of the heterotopic salivary gland tissue in the lymph nodes, causing the lesion. However, there is no substantial evidence for implicating EBV to be a causative factor.
Warthin’s tumor is almost usually restricted to the parotid gland, with very rare instances of manifestation in the sub-mandibular or other minor salivary glands. It predominantly manifests in males, in the 6th to 7th decade and presents as a slow growing, painless, nodular mass usually 3-4 cm in size. Alternatively, it may in some instances, present with pain and even ear symptoms like tinnitus, earache and deafness. Rarely, the lesion may cause facial nerve palsy and such lesions may be clinically mistaken for a malignancy. This tumor may also manifest bilaterally in 5-14 % of the cases, affecting both the parotid glands, arising either simultaneously (synchronous) or in one gland after another at different times (metachronous).
Under the microscope, Warthin’s tumor consists of numerous cystic spaces lined by ductal epithelial cells. The cystic spaces are filled with secretions, consisting of proteinaceous material and cellular debris. The epithelial layer lining these cystic spaces are thrown into numerous papillary folds that extend into the lumen. On closer look, the epithelial lining consists of 2 layers of cells, with both layers being oncocytic. Oncocytes are cells that are packed with mitochondria and appear granular and deep pink. The layer immediately next to the lumen comprises of tall columnar cells, with palisaded nuclei, that are centrally placed. The 2nd layer of cells surrounding the luminal cells appear cuboidal and are called basal cells.
The cystic spaces lined by oncocytic cells are surrounded by a lymphoid stroma comprising of lymphocytes with occasional plasma cells and histiocytes. The stroma may sometimes harbour germinal centres.
TREATMENT AND PROGNOSIS
Surgical excision of the tumor is the treatment of choice. This is accomplished by local resection with minimal surrounding tissue while some prefer superficial parotidectomy. Surgical removal is usually accomplished easily and without damage to the facial nerve due to the superficial location of the tumor.
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