FROM THE ARCHIVES OF THE AFIP - TERATOMAS, DERMOIDS, AND EPIDERMOIDS OF THE HEAD AND NECK

Dermoids and epidermoids are ectoderm-lined inclusion cysts that diffe r in complexity: Epidermoids have only squamous epithelium; dermoids c ontain hair, sebaceous and sweat glands, and squamous epithelium, Both arise from trapped pouches of ectoderm, near normal folds, or from fa ilure of surface ectoderm to separate from the neural tube. These slow ly expanding, unilocular, cystic masses may produce only mild symptoms , They commonly occur in the orbit, calvarial diploic space, and intra cranially (the posterior and middle fossae), They may be complicated b y rupture leading to chemical meningitis, and dermoids with a fistulou s tract can become infected. Craniofacial teratomas are true neoplasms arising from misplaced embryologic germ cells, They contain a medley of heterogeneous tissues, typically reflecting more than one of the th ree embryonic germ layers, They are usually multiloculated masses, oft en large, with complex radiologic characteristics. Craniofacial terato mas may manifest prenatally with macrocrania or polyhydramnios, during a difficult delivery, or postnatally as a life-threatening mass causi ng brain herniation, hydrocephalus, respiratory distress, or feeding d ifficulty, In infancy, they can be biologically benign, even when thei r histologic characteristics are immature, Surgery is the treatment of choice for all three masses and may be curative.