Thoracic Spinal Angiolipoma: A Case Report and Literature Review

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Abstract

INTRODUCTION

Spinal angiolipoma (SAL) occurs in approximately 0.04% to 1.2% of all spinal tumors17,23,28,30,32,37). SAL is a benign tumor made up of adipose tissues and vasculature1,16,22,23,27-30,32,34,35,38,39,42). Although the tumor is usually found within the thoracic epidural space, SAL is sometimes found within the lumbar epidural space. It is also found within the cervical and sacral epidural space, though rarely9,18,32,35,38). Usually, SAL grows slowly and compresses the spinal cord or root, causing symptoms gradually4,12,18,31,40,46). SAL can be subdivided into two types, non-infiltrating and infiltrating1,18,23,32,33,35,40). The non-infiltrating type of SAL is easily dissected from the surrounding dura and adjacent tissue because it is encapsulated. In contrast, the infiltrating type is not encapsulated, making total removal difficult1,23,33,39,42). Magnetic resonance imaging (MRI) has an important role in diagnosing SAL, but the gold standard for diagnosis is pathological diagnosis1,4,18,23,32,38). The main treatment in SAL cases is surgical removal. Even when infiltrating type is subtotally removed, the prognosis is good18,27,33,39,40). We report a case of a patient with SAL complaining of cord compression symptoms arising from the thoracic level.

CASE REPORT

An 81-year-old male patient came to our clinic complaining of numbness in both legs lasting one year. The patient complained of both thigh pain and numbness in both feet. His big toe dorsiflexion motor grades (both toes) were 3+ with gait disturbance. The diagnosis was difficult not only due to the rarity of this type of tumor but also due to the patient’s history of brain meningioma. In August 2019, the patient underwent a craniotomy to remove a meningioma. This explains why the possibility of the post-operative spinal seeding of epidural meningioma could not be ruled out. After admission, MRI imaging showed a hyperintense mass in both T2 (Fig. 1A) and T1 (Fig. 1B) imaging at the T11 and T12 levels. It also showed homogenous enhancement in T1-contrast enhanced image (Fig. 1C). The mass was compressing the cord at that level and had spread to the neural foramina. Based on the patient’s history and the MRI imaging findings, we suspected an epidural meningioma.

Fig. 1.

(A) T2-weighted magnetic resonance imaging (MRI) showing a hyperintense mass at T11-12. (B) T1-weighted MRI showing a hyperintense mass at T11-12. (C) Post-contrast T1-weighted MRI showing a well-enhanced mass compressing the spinal cord and spreading to the neural foramina at T11-12.

We carried out surgical tumor removal. Pedicle screws were inserted at the T11-T12 level. Laminectomy and facetectomy were done. An Encapsulated mass with easily identifiable margins was exposed and removed. Postoperative MRI confirmed that the mass was completely removed (Fig. 2). Pathology revealed adipocytes with abundant vasculature, making the final diagnosis SAL (Fig. 3). The patient recovered well. His preoperative myelopathy symptoms were gradually relieved. In June 2023, approximately five months after surgery, the patient visited an outpatient clinic. Symptoms he complained of before the surgery, such as gait disturbance, motor weakness, and numbness in both feet, had disappeared.

Fig. 2.

(A) Intraoperative picture showing a yellow mass on the dura at T11-12. (B) Complete removal of the mass through laminectomy and facetectomy. (C) Complete removal of the mass on postoperative magnetic resonance imaging.

Fig. 3.

Histopathological image (hematoxylin and eosin stain) showing mature adipocytes with extensive vasculature.

DISCUSSION

SAL was first reported 1890 by Berenbruch and was defined as ‘spinal angiolipoma’ in 1961 by Howard and Helwig6,13,25,35,39). Benvenutti-Regato et al.5) reported that there were 178 cases of SAL up to 2015. We found 51 more reported cases (Table 1) since 2016, making a total of 229 reported cases. Of the 51 cases, 31 were reported at the thoracic level, 13 at the lumbar level, one at the sacral level, four at the thoracolumbar level, and two at the lumbosacral level. According to Rkhami et al.30), 78% of SALs are found at the thoracic level, followed by 10% at the lumbar level and, less than 1% at the cervical or sacral level.

Table 1.

Review of reported cases of spinal angiolipoma since 2016

The tumor is commonly found in the posterior cord at thoracic levels. The symptoms are related to the compression of the thoracic spinal cord31,40). Common symptoms include lower limb weakness, sensory changes, and numbness31,40). Symptom progression can vary widely among patients, ranging from simple back pain to acute paraplegia18,31,40).

According to Josephs et al.17), several factors related to the growth of SAL are trauma, weight gain, and hormones30). Obesity and pregnancy can promote SAL growth by stimulating hormones that affect the growth of adipose tissue4,9,23,25,28,31,38).

Differential diagnoses of SAL include arteriovenous malformations, nerve sheath tumors, meningioma, metastasis, chronic extradural hematoma, and lymphoma4,12,24,25,29). Among them, the growth patterns of spinal epidural meningiomas are commonly the en plaque, dumbbell or fusiform type24,44). The mass may extend toward the intervertebral foramen with a characteristic dura tail24,44). Out of the three common shapes, the fusiform-shaped meningioma must be differentiated from SAL24,44). Our patient’s imaging study revealed a mass at the thoracic level. The shape was fusiform with slight dural thickening extending to the intervertebral foramen (Fig. 1). Based on the imaging study and the patient's history of meningioma, we preoperatively suspected a case of spinal meningioma.

MRI is the most valuable tool for diagnosing SAL before surgery1,4,19,23,27,38,46). Though tumors display variable intensity across T1 and T2, they are usually hyperintense in both T1 and T2-, and homogenously enhanced in T1 images1,8,18,29,30,38,39). However, in SAL cases with profuse vasculature, T1 displays hypointensity and T2 displays hyperintensity39,41,42,46).

SAL can be subdivided into two types. The first is the non-infiltration type. This subtype is more common and is commonly found within the dorsal epidural space; it is encapsulated, distinguishing it from the surrounding tissue1,28,32,38,42). Therefore, this type can be completely removed1,18,28,32,33,35,38,42,46). The second type is the infiltration type, which is less common. This type is commonly found on the ventral side of the spinal cord. It is difficult to distinguish from the surrounding tissue. It usually invades the vertebral body because it is not encapsulated1,18,28,32,33,35,38,42,46). SAL usually shows a good prognosis with no additional treatments needed, even when the tumor is subtotally removed1,4,12,16,18,21,27,29,31,46). However, Wang and Tang39) reported that myelopathy can recur in cases of incomplete removal due to dura infiltration.

Total resection is the treatment of choice. Most patients of surgically removed SAL are relieved of neurologic symptoms1,4,8,18,19,21,22,42,43).

The choice of surgical method depends on the tumor’s axial localization (ventral or dorsal) and the involvement of the intervertebral foramen45). The tumor is usually located dorsally without involvement of the intervertebral foramen1,28,32,38,42). In such cases, total resection is relatively easy without dura injury 45). However, in cases of a ventral location with the involvement of the intervertebral foramen, wider resection is necessary45). In our case, the wide resection method with laminectomy and facetectomy was selected, as the tumor was located dorsally-, but invaded the intervertebral foramen. After removal of the tumor, screw fixation was performed for spine stability.

Pathologically, SAL shows a characteristic appearance of mature adipocytes and abnormal vascular elements, including capillaries, thin- or thick-walled vessels, and small arteries4,20,37,39,42,46). Furthermore, mature fat tissue and blood vessels usually exist at 1:3 to 2:3 39).

CONCLUSION

SAL is a rare benign tumor composed of fat tissue and vasculature. The case reported here was the non-infiltration type with a clear margin. After the tumor was completely removed, the patient was discharged with improved myelopathy symptoms. Treatment for SAL involves surgical resection. The prognosis is good after surgery.

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