It is believed that the growth pattern of lipomas in lipomeningomyelocele (LMMC) is similar to that of adipose tissues
in other parts of the body. Although it is widely accepted that congenital spinal lipomas are anatomically stable lesions,
we present a case of a rapidly growing intradural lipoma accompanied by neurological deterioration. An 8-year-old girl
with a rapidly regrowing LMMC was admitted to our neurosurgical clinic. She was delivered by Cesarean section and,
at 47 days after birth, she underwent urgent detethering surgery because of deteriorating weakness. We performed her
detethering operation immediately, rather than at 3 months as had been previously scheduled, because of the rapidly
growing lipoma. The second operation was performed at age 8 years because of a regrowing intradural lipoma and
aggravating leg deformity. The most problematic issue in treating LMMC is deciding which patients and what symptoms
are best suited to surgical treatment. Even if LMMC is expected to be surgically corrected at 2 or 3 months after birth,
lipomas could grow more rapidly than expected. Close monitoring and follow-up before and after surgery are needed
for optimum surgical timing in order to avoid deteriorating neurological symptoms. The possibility of the rapid growth
of intradural lipomas offers additional support for early prophylactic surgery in patients with LMMC. The potential for
rapid growth of spinal lipomas should be considered during the first few months of life. Early diagnosis and optimal
surgery are still essential for the treatment of patients with LMMC, since there is a high likelihood that residual neurological
function can be preserved.