Ectomesenchymal chondromyxoid tumor

Ectomesenchymal chondromyxoid tumor (ECT) is a benign intraoral tumor with presumed origin from undifferentiated (ecto)mesenchymal cells.

[2] Patients present with a painless, slow-growing mass usually within the tongue (most commonly the anterior dorsal tongue).

They included pleomorphic adenoma, myoepithelioma, myxoid neurofibroma, neurothekeoma (nerve sheath myxoma), chondroid choristoma, extraskeletal myxoid chondrosarcoma, focal oral mucinosis, and an ossifying fibromyxoid tumor of soft parts.

[1] Exceedingly rare, this tumor develops in a wide age range, although often in young patients without a sex predilection.

The vast majority develop within the anterior dorsal tongue,[1] with palate and base of tongue rarely affected.

A very low power hematoxylin and eosin stained slide of an ectomesenchymal chondromyxoid tumor. Note the well demarcated tumor, separate from the overlying, intact squamous mucosa.
An intermediate power hematoxylin and eosin stained section of an ectomesenchymal chondromyxoid tumor, showing skeletal muscle entrapment. Note the "net-like" appearance (lower portion).
The overlying surface epithelium is intact and unconnected to the well circumscribed, but unencapsulated ectomesenchymal chondromyxoid tumor of the tongue. There are numerous skeletal muscle bundles at the periphery of the tumor.
Alcian blue (pH at 2.5) stains the myxoid background material brightly blue in this ectomesenchymal chondromyxoid tumor of the tongue.