Repeated aspiration and sclerotherapy to manage recurrent spinal epidermoid cyst

Abstract

Spinal epidermoid cysts are rare lesions and epidermoid cyst in intramedullary location is even rarer. Surgical excision is the mainstay of treatment; however, in cases of recurrence, repeat surgery becomes quite difficult. Treatment of recurrent intramedullary epidermoid cyst by surgery alone is a challenge. We managed one such rare case with repeated aspiration and sclerotherapy. Here, we have highlighted hypertonic saline sclerotherapy as a promising tool to treat recurrent spinal epidermoid cysts.

Background

Spinal epidermoid cysts are rare cystic lesions lined by squamous epithelium and may be congenital or acquired in origin.^1–4 Congenital lesions are usually associated with other spinal dysraphism, whereas acquired lesions are mostly due to recurrent lumbar punctures.⁵ Conus medullaris epidermoid cysts are extremely rare clinical entity and can be intramedullary or extramedullary.^1–3 Acquired cysts are generally intramedullary in location with lumbar puncture being the most common aetiology. Complete surgical excision is the treatment of choice and then recurrences are rare. However, if the lesion recurs, it becomes very difficult to manage it by repeated surgery.^{4 6} We report a case of young female physician presenting with recurrent conus epidermoid cyst, managed with repeated aspiration and hypertonic saline sclerotherapy.

Case presentation

A 30-year-old female physician with a previous history of two caesarean sections under spinal anaesthesia presented with weakness of bilateral lower limbs and foot drop after 1 year of her last caesarean section. MRI of lumbosacral spine (LS) revealed a cystic lesion arising from the conus medullaris. Surgical excision of the cyst was performed after laminectomy; however, only partial excision could be performed as the cyst wall was adhered to the adjacent nerve roots. On histopathology, diagnosis of epidermoid cyst (epidermal inclusion cyst) was made. Postoperatively, her symptoms resolved and she became totally asymptomatic. She again presented with similar symptoms 9 months after the first surgery. A repeated MRI of LS revealed similar cystic lesion in the region of conus medullaris (figure 1). Subsequently, she underwent two more surgeries and marsupialisation of the cyst. However, her symptoms reappeared within a year of repeated surgery. The last two surgeries were quite difficult due to presence of scarring and adhesions.

Figure 1.

Postoperative MRI of the LS spine T2 weighted images (T2WI) in sagittal plane (A, C) and T1WI (B) showing a cystic lesion (arrow) attached to the conus and adherent to cauda equina nerve roots. T2WI in axial plane (D, E) showing cystic lesion with heterogenous content within.

Since the operating surgeon as well as the patient was reluctant for any further surgery, she has referred for image-guided aspiration of the cyst to resolve her symptoms. Initially, she underwent ultrasound-guided aspiration of the cyst two times, which led to symptomatic relief lasting for 6 months. Then, she underwent noncontrast CT-guided aspiration (figure 2) two times with recurrence of symptoms and cyst refilling within 6 months after the aspiration. This time, we thought of instillation of some sclerosing agents, so that cyst refilling could be slowed down. Due to the intraspinal location and proximity to neural structures, we used 20% hypertonic saline in place of other sclerosing agent to minimise postinjection inflammation. The patient’s symptom-free duration was increased up to 12 months after combining the aspiration with irrigation of cyst using hypertonic saline.

Figure 2.

NCCT axial images showing Chiba needle within the epidermoid cyst (A), injected non-ionic contrast (blue arrows) delineating the cyst wall (B, C). Cyst content aspiration being performed in decubitus position with tip of needle within the cyst (C) and post aspiration image showing air (white arrow) within the cyst cavity (D). NCCT, noncontrast CT.

Differential diagnosis

The close differentials include spinal arachnoid cyst, dermoid cyst and neurenteric cyst. Arachnoid cysts follow cerebrospinal fluid (CSF) intensity on all MRI sequences and do not show diffusion restriction on diffusion-weighted imaging (DWI), whereas significant diffusion restriction is seen in cases of epidermoid cyst. Dermoid cysts usually contain fatty elements. Spinal neurenteric cysts are most commonly found ventral to spinal cord and usually associated with vertebral anomalies.

Treatment

Aspiration and sclerotherapy

Aspiration of cyst content was done in conscious sedation under the cover of intravenous (IV antibiotic and steroid injection. Steroid premedication was given to prevent any chemical meningitis due to possible spillage of cyst content into the CSF. The patient was placed on the table in prone position. Under aseptic precautions, local anaesthesia was given. Then the cyst content was aspirated by a 18G Chiba needle. The aspirate was thick in consistency with multiple whitish flakes repeatedly blocking the aspiration needle. The cavity was irrigated with normal saline to remove the contents completely. During CT-guided procedure, small amount of nonionic contrast was injected to delineate the cyst and to ensure completeness of cyst evacuation. Then, for hypertonic saline sclerotherapy, 20% hypertonic saline was injected into the cyst cavity. The amount of hypertonic saline injected was half the volume of the cyst. The hypertonic saline was left inside the cyst for 30 min and then completely reaspirated. After that, the cavity was again irrigated with normal saline to remove the contents completely.

Outcome and follow-up

The patient is under follow-up for 9 years without any neurological deficit. The refilling time of the cyst as well as patient’s symptom-free duration were increased from approximately 6 months to 12 months after hypertonic saline sclerotherapy.

Discussion

Epidermoid cysts account for less than 1% of all intraspinal tumours.^1–3 Spinal epidermoid cysts are usually intradural extramedullary. Only 60 cases of intramedullary epidermoid cysts have been reported so far.^1–4 Acquired epidermoid cysts usually occur several years after single or multiple lumbar spinal punctures and are thought to result from iatrogenic implantation of skin fragments into the spinal canal.⁵ They tend to develop close to the sites of earlier lumbar puncture, usually near the conus medullaris and cauda equina. They present clinically after a variable period of time, ranging from 2 to 10 years. They can grow slowly in the region of cauda equina without producing symptoms of nerve compression. Symptoms are directly related to the size and location of the lesion. Signs and symptoms at presentation are usually neurological, such as progressive paraparesis, sensory loss, urological manifestations, backache or lower limb pain. Eventually, all the patients with lesions in the cauda equina region report severe pain radiating towards the roots of the compressed nerves.^{6 7} On MRI, these lesions are usually well defined and appear hypointense on T1 weighted images (T1WI) and hyperintense on T2WI. Signal intensity may be variable depending on composition of the cysts. On DWI, they characteristically show significant diffusion restriction.^{1 2}

Complete surgical excision of the epidermoid cyst along with the capsule is the standard treatment. Sometimes, the capsule of the cyst is adherent to the surrounding cord/neural tissue, and in that case, an attempt to perform complete excision may result in neurological deficit. Preoperative symptoms may resolve completely even after partial resection of the cyst. Recurrence is rare after complete removal of the lesion, and the rate of recurrence is inversely proportional to the extent of the resection.^{4 8}

In our case, the epidermoid cyst was adhered to the conus medullaris and adjacent neural elements resulting in incomplete surgical resection and that led to repeated recurrences. Furthermore, repeated surgical procedures increase the risk of injury to the neural elements and also are difficult to perform due to the presence of scars and adhesions. Image-guided aspiration of the cyst leads to short-term resolution of symptoms. There is a dilemma regarding the optimum line of management in such patients. We did not find any report of sclerotherapy in cases of spinal epidermoid cyst on review of the literature. With repeated aspiration and hypertonic saline sclerotherapy, we have managed our patient safely for over 9 years and she is able to live a normal life at present. We refrain from using more potent sclerosing agent in spinal canal lesion, as that may cause damage to neural tissue leading to permanent neurological deficit. The advantages of hypertonic saline are low cost, lack of allergic reaction and rapid clinical effect. The use of percutaneous hypertonic saline as sclerosing agent has been reported in treatment of hydatid disease of liver and symptomatic simple renal cysts.^9–12 It is supposed to induce inflammation leading to destruction of lining epithelium and reduction or resolution of the cystic lesion. Hypertonic saline sclerotherapy resulted in increasing symptom-free interval in our case.

The adverse effects of hypertonic saline could be related to its nonspecific action of cell destruction due to osmotic effect. It can lead to cutaneous ulceration, irritation of adventitial nerves causing postinjection pain and transient muscle cramping in some patients. Therefore, injection technique, concentration and injection volume are particularly important while using this agent for sclerotherapy.¹³

Learning points.

• Acquired spinal epidermoid cyst is a rare clinical entity and complete surgical excision is the treatment of choice.

• Preoperative diagnosis is based on MRI findings and these lesions characteristically show significant diffusion restriction on diffusion-weighted imaging.

• In recurrent cases, repeated aspiration and hypertonic saline sclerotherapy are effective and may be performed safely and leading to increased symptom-free duration.

Ethics statements

Patient consent for publication

Obtained.