Calvarial dermoids and epidermoids in infants and children: sonographic spectrum and follow-up.
Dermoids and epidermoids are defined as ectodermal inclusion cysts. The aim of this study was to evaluate the spontaneous natural behavior and the ultrasonographic appearance of calvarial dermoids and epidermoids. The ultrasonographic image datasets of 100 consecutive children up to 4 years of age (52 females, 48 males; age range at first examination 1 week to 40 months, mean age 8.3 +/- 6.9 months) presenting with a firm palpable calvarial mass (103 lesions) were studied retrospectively. All ultrasound (US) examinations were performed using a 7- to 10-MHz linear transducer including B-mode and color Doppler sonography. US follow-up studies (up to 47 months) could be achieved in 30 patients with 33 lesions. At first presentation, all 103 lesions demonstrated very similar US features: a round or oval configuration (diameter 3-18 mm), hypoechogenic, and homogeneous internal structures with a marked hyperechogenic superficial capsule, which were localized adjacent to or expanded into the osseous external calvarial table. No conspicuous flow signs on color Doppler were seen. In 33 lesions with US follow-up investigations, 49% showed variable signs of regression: reduction of size, increase of internal echogenicity, and decrease of demarcation. Eight lesions (24%) remained unchanged. A slight progression up to a maximum diameter of 17 mm but without any increase in osseous destruction was observed in the remainder (27%). There was no lesion with a complete destruction of the underlying bone and no intracranial extension in any of the cases. Calvarial dermoids and epidermoids in infants and children show a benign natural behavior with spontaneous regression in a large number of cases. On US, they demonstrate uniform pathognomonic features enabling the correct diagnosis in any of those lesions. Thus, additional, mainly radiation burdening and sometimes misleading imaging techniques should be restricted. Surgical treatment protocols should be handled conservatively and lesions should be primarily followed-up clinically and by US.