permits herniation of intracranial tissue, or they may develop after trauma that disrupts the bone and dura mater of the anterior cranial fossa. An intraorbital location leads to proptosis or downward displacement of the globe. Anterior presentation takes the form of a subcutaneous mass that can be misdiagnosed as a dacryocystocele. However, encephaloceles and meningoceles are typically located above the medial canthal tendon; dacryocystoceles are typically located below it (see Chapter 19). Pulsation of the globe or the mass from the transmission of intracranial pulse pressure is characteristic. Neuroimaging readily confirms the diagnosis.

Teratoma

Choristomatous tumors that contain multiple tissues derived from all 3 germinal layers (ectoderm, mesoderm, and endoderm) are referred to as teratomas. Most teratomas are partially cystic, with varying fluid content. Orbital teratomas account for a very small fraction of both orbital tumors and teratomas in general. The clinical presentation of orbital teratomas is particularly dramatic, with massive proptosis evident at birth (Fig 18-24). In contrast with teratomas in other locations, which tend to show malignant growth, most orbital lesions are benign. Surgical excision, facilitated by prior aspiration of fluid, can often be accomplished without sacrificing the globe. Permanent optic nerve damage from stretching and compression usually results in poor vision in the involved eye.

Figure 18-24 Congenital cystic teratoma originating in the left orbit of a 1-day-old girl.

Ectopic Lacrimal Gland

These are rare choristomatous lesions that may present with proptosis in childhood. Cystic enlargement and chronic inflammation sometimes aggravate the condition.