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Physiological rapid growth of spinal lipoma in the early postnatal period
Kazuhisa Yoshifuji1, Nobuhito Morota2, Yoshinori Omori1
11Division of Pediatric Neurosurgery, Hokkaido Medical Center for Child Health and Rehabilitation, Sapporo, Japan.
Insights
Spinal lipomas grow rapidly in infants, particularly under 1 month old, mirroring normal fat tissue growth and BMI changes. This rapid growth necessitates close monitoring due to potential spinal canal obstruction and cord distortion in infants younger than 3 months.
Area of Science:
- Pediatric Neurosurgery
- Developmental Biology
- Radiology
Background:
- Spinal lipomas are congenital malformations that grow with age.
- Understanding their growth patterns is crucial for managing potential complications.
Purpose of the Study:
- To analyze the natural volume changes of spinal lipomas in relation to subcutaneous fat and Body Mass Index (BMI).
- To assess the growth dynamics of spinal lipomas in early infancy.
Main Methods:
- Retrospective analysis of 27 patients with conus spinal lipoma using serial MRI.
- Categorization of patients into age groups (<1 month, 1-2 months, ≥3 months) for comparative growth rate analysis.
- Measurement of lipoma dimensions, subcutaneous fat thickness, spinal canal growth, and BMI changes.
Main Results:
- Spinal lipomas exhibited significant growth rates (up to 199% in dorsoventral direction) within 83 days, especially in infants <1 month.
- Lipoma growth closely correlated with subcutaneous fat growth and BMI increase.
- Rapid lipoma growth exceeded spinal canal growth in infants <3 months, leading to subarachnoid space obstruction (35.3%) and spinal cord distortion (48.1%).
Conclusions:
- Spinal lipomas demonstrate rapid postnatal volume increase, particularly in the first month of life.
- This growth parallels normal subcutaneous fat expansion and BMI changes.
- Close observation is vital in early infancy due to the risk of neurological compromise from rapid lipoma expansion.
Objective:
Spinal lipomas are congenital malformations. They do not express tumorous growth but are found to increase in volume like other normal subcutaneous fat tissue during the early postnatal period. To understand the natural course of volume changes in spinal lipomas, the authors measured the changes in size of spinal lipomas together with the normal subcutaneous fat in relation to BMI.
Methods:
A total of 27 patients with conus spinal lipoma excluding lipomyelomeningocele who underwent MRI twice before surgery (on initial diagnosis and immediately preoperatively) were included. Patients' ages at the time of the first MRI ranged from 0 to 32 months (mean 2.9 months, median 1 month). Candidates were categorized by age into three groups: < 1 month, 1-2 months, and ≥ 3 months. The growth rate of the spinal lipomas (in three directions), change in thickness of the normal subcutaneous fat, growth rate of the normal spinal canal (dorsoventral direction), and change in BMI were retrospectively analyzed between the three groups.
Results:
The mean interval between MRI studies was 83.1 days. During this time, the mean lipoma growth rates were 199%, 149%, and 133% in the dorsoventral, lateral, and craniocaudal directions, respectively (with 100% representing the first measurement). The mean change in the thickness of the normal subcutaneous fat was 183%. The mean growth of the normal spinal canal was 111%. The mean increase in BMI was 124%. These rates were all significantly higher in the younger groups. There was no significant difference in the growth rates between the lipoma and the subcutaneous fat in every age group. In contrast, the growth rate of the lipoma significantly exceeded that of the spinal canal in patients younger than 3 months. The subarachnoid space around the lipoma became obstructed in 35.3%, and spinal cord distortion occurred in 48.1% of the patients younger than 3 months.
Conclusions:
Spinal lipomas rapidly increase in volume before the age of 3 months and especially in infants younger than 1 month. Their features closely correlate with the physiological growth of the normal subcutaneous fat and the increase in BMI. The rapid growth of lipomas suggests the importance of close observation in this period, keeping in mind the typical anatomical changes of lipomas and their surrounding structures.
