Noncontiguous Double Spinal Lipoma with Tethered Cord and Polydactyly: Two Different Embryological Events in One Patient.

Lumbosacral lipoma is reported to occur in 4-8 of 100,000 patients. Sixty-six percent of lipomyelomeningocele in young patients have accompanied by hypertrophic filum terminale. It is rare to find two isolated spinal lipomas simultaneously. Embryological origin of dorsal and filar lipomas is different from each other and hence rarer to find them together. Radical resection is now being preferred for better long-term progression-free survival. We report an interesting case of spinal dysraphism in a 4-month-old female child with protruding, nontender, soft, subcutaneous 5 cm × 7 cm mass of the lumbosacral area that had been present since birth. Other anomalies included polydactyly of left hand. Magnetic resonance imaging demonstrated two isolated spinal lipomas, a transitional type and a terminal type filum lipoma with an interval of normal filum between the two. The findings were confirmed at surgery and detethering done along the white plane with neural placode reconstruction as described by Dachling Pang. The child had an uneventful postoperative recovery.

INTRODUCTION

Lumbosacral lipomas occur in 4–8/100,000 of the general population. It is reported as the most common cause of tethered cord syndrome.[12] In addition, lipomyelomeningocele (LMM) was reported to be present in 25%–30% of children with tethered cord syndrome.[34] Although 66% of LMM in young patients are accompanied with hypertrophic filum terminale, it is rare to find two isolated spinal lipomas simultaneously.[5] Partial resection of complex spinal lipomas is associated with high rate of symptomatic recurrence due to retethering. Total resection of lipomas and aggressive neural placode reconstruction is now advocated for better progression-free survival (PFS).[6]

In this report, we describe a 4-month male child with two combined spinal lipomas of transitional and filum terminal types with a polydactyl of left hand who underwent total excision of both the lipomas with placode reconstruction.

CASE REPORT

A 4-month-old female baby presented with a 5 cm × 7 cm sized protruding, nontender, soft, subcutaneous mass in the lower lumbosacral area which was observed since birth [Figure 1]. There were no specific abnormal findings on the neurologic examination. The child had an additional finding of polydactyl on his left hand.

Figure 1

Clinical image showing dorsolumbar lipoma

The magnetic resonance imaging demonstrated two fat masses with high signal intensities in T1- and T2-weighted images, suppressed on short TI inversion recovery images from the L3 area to the sacrum [Figure 2]. Through the bony defect from L5 to S1, the subcutaneous fat was connected to the spinal cord and there was found as a spinal lipoma of the transitional type in the area of L3–L5. In addition, the other spinal lipoma of the terminal type was observed on the filum terminale. The conus and terminal cord were tethered and demonstrated a syrinx.

Figure 2

Magnetic resonance imaging T1-weighted, T2-weighted, and fat suppression images demonstrating noncontiguous spinal lipomas

At surgery, L3 to S2 laminectomy was performed and complete excision of the transitional lipoma with preserving the white plane as described by Pang et al. was performed. Filum lipoma was excised [Figure 3]. Placode reconstruction was performed withPDS 8/0 suture and was water-tight, but lax dural closure achieved with 5-0 prolene. The child had an uneventful recovery.

Figure 3

Operative photographs showing noncontiguous double lipomas and white plane after complete excision of transitional lipoma

DISCUSSION

Congenital spinal lipomas constitute a heterogenous group of spinal dysraphisms.[7] Different terms have been coined in literature for these lesions. Pierre-Kahn et al.[8] used the term lumbosacral lipomas and subdivided them into lipomas of conus and lipomas of filum. They used the term LMM for meningocele, which was associated with subcutaneous lipoma. Chapman[9] categorized conus lipomas into dorsal, caudal, and transitional types.

Premature dysjunction hypothesis as proposed by McLone and Naidich[10] explains the development of dorsal and conus lipomas while maldegeneration processes of the caudal cell mass in secondary neurulation probably explains development of terminal type of lipomas.[11]

However, in our case, where there were two separate lipomas, a transitional variety and terminal filar variety, a combination of the two events coincidentally involved in different embryonic periods, resulting in two different isolated types of spinal lipoma[12] can be the plausible explanation.

Total/near total resection of complex spinal cord lipomas and complete reconstruction of the neural placode produces a much better long-term PFS than partial resection. There are, in fact, strong indications that partial resection causes exuberant scarring at the lipoma-cord interface and consequently worsens prognosis compared to no surgery. Sharp dissection with microscissors is used to locate a thin but distinct silvery white plane between fat and cord at the demilune of the rostral fusion line[6] with neural placode reconstruction can help in achieving total to near total excision as in our case.

CONCLUSIONS

Double spinal lipomas represent an interesting set of patients where two different embryological mechanisms are responsible for the formation of two noncontiguous lipomas. A complete excision along the silvery plane and placode reconstruction should be performed to have a longer PFS.

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Conflicts of interest

There are no conflicts of interest.