MYOEPITHELIOMA
- It is a benign epithelial tumor which is composed of tumor cells exhibiting myoepithelial differentiation and not the ductal differentiation.
- These tumors represent 2% of all the benign tumors of salivary glands.
- Both sexes are equally affected
- Peak incidence is in 4th decade but can occur at any age.
- Most common sites are parotid and hard and soft palate (can occur in any salivary glands)
Gross – well circumscribed yellow-tan tumor with glistening cut surface.
Microcsopy –
- Tumor has fibrous capsule and is composed of tumor cells arranged in lobules. types of tumor cells seen in myoepithelioma are
- Spindle cells
- Epithelioid cells
- Clear cells
- Plasmacytoid cells
- Tumor shows hyalinized stroma and in many tumors abundant mucoid material is noted
Immunohistochemistry – Tumor cells are positive for CK5/6, CK14, P63, Maspin, CD44v6, Alpha smooth muscle actin, Caldesmon, Calponin, smooth muscle myosin heavy chain and Galectin-1. CK 14 is expressed consistently
Treatment – Surgical excision with tumor free margins. Recurrence can occur.
Cords 0f plasmacytoid tumor cells arranged in nodules separated by fibrous septa. Interstitial mucoid material is noted (H&E,X40)
Cords 0f plasmacytoid tumor cells arranged in nodule separated by fibrous septa. Interstitial mucoid material is noted (H&E,X100)
Plasmacytoid tumor cells arranged in microcystic pattern in the mucoid background (H&E,X100)
Plasmacytoid tumor cells arranged in nodules with interstitial mucoid stroma (H&E,X100)
Plasmacytoid tumor cells having eccentrically placed nuclei and abundant, eosinophilic, “hyaline” cytoplasm (H&E,X400)
Plasmacytoid tumor cells in the myxoid background (H&E,X400)
Plasmacytoid tumor cells having eccentrically placed nuclei and abundant eosinophilic “hyaline” cytoplasm. interstitial tissue shows mucoid material (H&E,X400)