Definition – Oncocytic tumor with malignant histologic features without any histopathologic features of other salivary glands
Clinical features :
Age – elderly ( Median age 67 years)
Site – common site is Parotid. Second common site is – submandibular gland
Gender – more common in males (M:F ratio is 1.6:1)
No association with prior radiation exposure
Presenting symptom – presents with painless slow growing swelling
some cases arise from prexisting oncocytoma
Tumor recurrence is seen in 56% of cases
Metastasizes to lung, kidney, liver, thyroid, mediastinum and bone
Pathological features
unencapsulated
single or multinodular, greyish-yellow irregular
cells show variation in size and shape and nuclear pleomorphism with vescicular nuclei
Cells may be arranged in ducts, nests, sheets or trabeculae that infiltrate adjacent connective tissue and salivary glan parenchyma
Atypical mitotic figure, perineural invasion and vascular invasion can be seen
coagulative tumor necrosis is present
For tumors with borderline atypical feature such as cellular atypia only, occasional mitotic figures or limited vascular invasion – Oncocytic neoplasm of uncertain malignant potential is considered