Table 1: Hidradenomata subtypes.

Ceruminous adenomaWell differentiated. Lack of invasion. Possibility of local recurrence if incompletely excised.
Pleomorphic adenomaSimilar to the pleomorphic adenomas found in sweat and salivary glands. Well-demarcated tumours.
Adenoid cystic carcinomaSimilar to tumours found in salivary glands. Propensity to invade nerves and around nerves.
Ceruminous adenocarcinomaInfiltrates soft tissue and bone.