According to the embryogenetic theory, the adamantinomatous subtype arises from epithelial remnants of the craniopharyngeal duct, which connects the stomodeal ectoderm with the evaginated
Rathke's pouch, which in turn forms the adenohypophysis.
Differential diagnosis of Thornwaldt's cyst is branchial cleft cyst,
Rathke's pouch cyst, adenoid retention cyst, meningocoele, sphenoid sinus mucocoele, JNA and possibly nasopharyngeal carcinoma.
A fold of tissue called
Rathke's pouch formed between the two tissues and eventually grew into a pituitary gland, complete with the five different types of hormone-producing cells found in a naturally formed gland.