Scanning guides dermoid treatment

Calvarial dermoids and epidermoids in young pediatric patients can be monitored using ultrasound alone instead of x-ray-based imaging, according to German researchers. Besides being safer and cheaper, sonography could rule out unnecessary surgeries.

CT and MR represent the current imaging standard for the examination of these lesions of the skull. Most of them are benign, however, and resolve with no intervention. Surgery is sometimes attempted, but it entails the risk of spreading infection if the mass ruptures.

Principal investigator Dr. Thomas Riebel said the recent study shows that ultrasound is adequate as the only necessary imaging modality for the correct diagnosis of these lesions.

"Other-especially radiation burdening-procedures are avoidable," he said.

Riebel and colleagues at the Charité Medical University in Berlin studied 100 consecutive children, 52 girls and 48 boys, aged four and younger. Each had at least one firm, palpable calvarial mass. The lesions were first studied with the children at a mean age of 8.3 months, ranging from one week to 40 months.

The researchers examined a total of 103 masses with both B-mode and color Doppler ultrasound. They found that each mass had a similar ultrasound profile, showing a round or oval outline with a diameter between 3 mm and 18 mm. The masses were hypoechogenic with homogeneous internal structures showing a marked hyperechogenic superficial capsule next to or extending into the osseous external calvarial table. The color Doppler exam showed no conspicuous flow signs.

Follow-up exams were possible on 33 lesions in 30 patients up to 47 months later. Signs of regression were visible in 49% of the lesions, including a reduction of size, increase of internal echogenicity, and decrease of demarcation. Eight lesions, or 24%, showed no change in the follow-up studies, and the remaining 27% showed an increase in the diameter up to 17 mm but no increase in bone destruction.

None of the cases showed a complete destruction of the underlying bone or intracranial extension. The researchers concluded that calvarial dermoids in infants and children resolve naturally in most cases and can be monitored easily with ultrasound, reducing the need for imaging modes requiring radiation. They published the study online June 17 in the journal Child's Nervous System.

Surgery should not be the first treatment recourse for these lesions any more since most will disappear spontaneously during the first three to four years of life. They should be followed by ultrasound instead, Riebel said.

"This conservative management is now accepted by the pediatric physicians and neurosurgeons at our university hospital, who for the last few years have stopped operating on those lesions completely," he said.

-By Wendy Despain