Microscopic description and IHC:

Histologic sections show a cystic tumor with surrounding fibrosis composed of epidermoid, intermediate and mucous cells.

There are also lymphoid cells with germinal centers found within the fibrosis.

Immunohistochemical features:
  • CK5/6 (+); highlights epidermoid cells
  • P63 (+); highlights intermediate and epidermoid cells

Discussion:

Mucoepidermoid carcinoma is a malignant glandular epithelial neoplasm characterized by mucus, intermediate and squamoid cells.

It is the most common malignant salivary gland tumor with the parotid gland being the most common location.

Women are more commonly affected than men (3:2) with a mean age in the 5th decade.

Most tumors are low grade with excellent prognosis.

Tumors of the submandibular gland have a poorer prognosis.

High grade tumors can show spread to regional lymph nodes and distant sites such as the lungs, bone and brain.

In this case, the tumor was a low grade mucoepidermoid carcinoma with benign lymph nodes.

References:

Goldblum, J. R. (2013). Head and Neck Pathology (2nd ed., Foundations in Diagnostic Pathology). Philadelphia, PA: Elsevier Saunders.

Thompson, L. D., MD, & Wenig, B. M., MD. (2012). Diagnostic Pathology Head and Neck (1st ed.). Altona, Canada: Amirsys.

CASE IMAGES