Anatomico-radiological study of intraosseous epidermoid cysts.

Anatomico-radiological study of 8 cases of intraosseous epidermoid cysts (1 in the skull, 6 in distal phalanges of the hand, 1 in distal phalanx of the foot with invasion of the adjacent joint). The epithelium was malpighian with hyperkeratosis (therefore the scales filled the cavity), sometimes with parakeratosis and even dyskeratosis but without signs of malignancy. The adjacent connective tissue and bone reactions were more active in the phalanx than in the skull and this could explain the frequent pain in the phalanges. The bone remodelling explains the radiological pictures and sustains the differential diagnosis. In 5 out of the 8 cases (particularly in the skull) a history of previous local trauma was present. However, the etiological importance of trauma should be discussed with respect to that of dysembryoplasia.