Pleomorphic adenoma parotid gland

Clinical details:

13 years old boy came with complaints of:

Swelling over left side of cheek - 3 years duration
Swelling showed progressive increase in size

The swelling was non tender, not associated with febrile illness.

FNAC report:

Fine needle aspiration cytology from the mass was reported as pleomorphic adenoma.

Surgery:

Since this is a surgical problem the patient was taken up for surgery under general anesthesia.

Discussion:

Pleomorphic adenoma is the commonest benign tumor involving the salivary glands. This is characterised by proliferation of glandular cells along with myoepithelial components. This tumor has a tendency for malignant transformation.

Histologically this tumor is highly variable and variations are evident even within individual tumors.
Classically these tumors show biphasic manifestation with admixture of varying amounts of polygonal salivary gland cells and spindle shaped myoepithelial cells. The underlying stroma could be mucoid / myxoid / cartilagenous / hyaline. Even though these tumors are not encapsulated but thickening of parotid fascia around the mass gives it an encapsulated appearance (pseudocapsule).

The main cause for this tumor is juxtapositioning of PLAG gene to the gene for beta catenin. This causes activation of catenin pathway leading on to inappropriate cell division.