Intramedullary Dermoid Cyst With Relatively Atypical Symptoms

A Case Report and Review of the Literature

Maryam Sanaullah; Sidra Mumtaz; Akhtar Amin Memon; Abdul Sattar Mohammad Hashim; Sanaullah Bashir


J Med Case Reports. 2013;7(104) 

In This Article

Case Presentation

A 14-year-old Sindhi boy presented to our hospital complaining of having had lower back pain for six months. The pain was followed by the development of weakness and numbness in his lower limbs. He had been constipated for a week prior to reporting. There was no history of urinary incontinence, infection, lumbar puncture, spinal trauma or previous spinal surgery.

The patient was initially diagnosed by a district registered medical officer (RMO) as having tuberculosis (TB) of the spine, the disease being endemic in the area, and was started on antituberculous therapy (ATT). In spite of three months of treatment, the weakness progressed until he became completely bedbound and unable to move. It was then that the patient was moved to a tertiary care hospital.

The patient's higher mental function was normal and his cranial nerves were intact. An assessment of his motor system revealed a reduced bulk of the flexor group of both lower limbs. There was hypotonia on the left side and power was grade 3/5 in both his lower limbs. Knee and ankle jerks of both lower limbs were absent. The motor examination of the upper limbs was unremarkable with the exception of areflexia, observed bilaterally. On sensory examination, there was hypoesthesia and decreased light touch and pinprick sensation in the L5/L4 dermatomes of his right lower limb. The sacral dermatomal sensations at S1 and S2 levels were also impaired. The overlying skin of the thoracolumber region was intact, showing no signs of inflammation, swelling or hairy nevi, or local hair growth. The rest of the systemic examination was unremarkable. There was no history of weight loss, night sweats, body aches or malaise. Baseline investigations revealed anemia and leukocytosis.

On radiological investigation, an MRI scan of the dorsal spine was performed with T1- (TR/TE 410/19) and T2- (TR/TE 3700/134) weighted images. The MRI scan evidenced a focal, well-defined space-occupying lesion measuring 1.50×0.6cm2, and abnormal signal intensity within the spinal canal, which was intradural as well as intramedullary in nature, since there was a splitting of the cord into two layers along the superior aspect of the lesion. The lesion was on the posterior aspect of the cord compressing the conus medullaris at the D12 and L1 level. No perilesional edema was observed.

The tumor was heterogeneous in intensity, localized, and its boundaries were well demarcated. It was hypointense at the T1-weighted frequency with a hyperintense signal area at the caudal end (arrow) (Figure 1) and appeared homogenously hyperintense on the T2-weighted images (Figure 2).

Figure 1.

Sagittal T1-weighted image shows a hypointense lesion with a hyperintense signal area at the lower end (arrowhead).

Figure 2.

Sagittal T2-weighted axial image showing a homogenously hyperintense lesion.

After all aseptic measures, surgical resection was accomplished through a posterior midline linear incision at the D12 and L1 level. All the layers of skin, the subcutaneous fat and the muscles were separated, the dura was opened and a laminectomy was performed. During the operation, the spinal cord was seen to be compressed and overdistended due to an intrinsic lesion. Myelotomy was performed and a well-demarcated, unilocular, grayish white intradural, intramedullary cyst was found involving the conus medullaris and extending from D12 and L1.

The cyst was evacuated and near-total excision was done from the neuronal tissue. Some 0.5ml of thick grayish yellow pus was obtained and sent for histopathology, which revealed aggregates of keratinocytes along with keratin flakes that confirmed the diagnosis of dermoid cyst.

A pus culture showed no growth after 48 hours of incubation at 37°C.

After one month of follow-up, there was no abnormal neurological sequelae, the improvement in motor power was grade 4/5 in both lower limbs and there was restoration of light touch and pinprick sensation. The patient was able to mobilize and walk with support.