1. Pleiomorphic adenoma

Staining: HE

Organ: Parotid gland

Description:

The bottom left half of the slide shows the normal fat rich, serous parotid gland.

The upper right half is the tumor. It consists of glandular structures and epithelial-like cells. There are also some areas inside the tumor with cartilage-like tissue.

Diagnosis: Pleomorphic adenoma

Causes:

• Chromosomal rearrangements involving PLAG1 gene (not important)

Theory:

This benign neoplasm gets its name from the pleomorphism it has. It consists of a mixture of ductal epithelial cells, myoepithelial cells and mesenchymal tissue like cartilage, loose connective tissue or even bone. We can therefore say that this tumor has both epithelial and mesenchymal differentiation.

This is the most common benign salivary gland tumor, accounting for around 80% of them. It’s most commonly found in the parotid but can be found in the submandibular or minor salivary glands as well. It usually presents as a palpable mass.

Treatment involves surgical removal, however complete removal is difficult because of the anatomical relationship with the facial nerve. This tumor has a high recurrence rate if not removed completely. It also has a high risk of turning malignant, turning into carcinoma ex pleomorphic adenoma, also called CEPA.

Pleomorphic adenoma usually grows small “feet”, called pseudopods, taking on a shape similar to a starfish with short legs. One pseudopod can be seen on the slide.

Overview of the slide

Basically every cell you can see around the cartilage is a ductal epithelial cell. You don’t have to identify a myoepithelial cell.