Acute Onset Paraplegia Due to Thoracic Angiolipoma: A Case Report and Review of the Literature

Spinal angiolipomas are rare and benign tumors which are composed of mature adipose tissue and blood vessels...


Introduction
Angiolipomas are subcutaneous benign lesions. Although angiolipomas are usually located at subcutaneous region, rarely they may locate at spinal canal. Spinal angiolipomas contains mature adipose tissue and blood vessels. Spinal angiolipomas (SAL) constitutes 0.14-1.2% of spinal tumors and 2-3% of extradural spinal tumors [1,2]. The most common presenting symptoms of SAL are chronic back pain, sensorial findings and muscle weakness [3]. Thoracic epidural region is the most common location of SAL [4]. Most of the SAL presents with progressive

Case Presentation
A 51-year-old female presented with chronical back pain without pregnancy, trauma or another pathological history. Magnetic resonance imagining (MRI) showed Grade1 anterololisthesis in the L4-5 level. Lumbar stabilization without posterior decompression was performed at another hospital for spondylolisthesis. Patient had weight gain due to immobilization because of lumbar stabilization operation and back pain. After 2months of post-operation, the patient presented with acute paraplegia. The patient was referred to our clinic for clinical investigation and treatment. Neurological examination showed flaccid paraplegia, hyperreflexia and bilateral positive babinski sign of bilateral lower extremity. Laboratory investigations revealed no abnormalities about infection. MRI showed posterior epidural lesion at T6-T9 level. On T1-weighted and T2-weighted MRI examination the tumor was homogeneously hyperintense. Prominent spinal cord compression was at T7-T8 level. T7-T8 hemilaminectomy performed without disruption of the facet joint. Intraoperatively yellow, firm adipose-like epidural lesion was found which was causing severe spinal cord compression. There was no invasion into dura matter or bone structures by lesion. The lesion was different from normal epidural fat tissue. The tumor had a good cleavage plan from dura mater. Extradural lesion was removed totally. The dura was not opened. Post operative period was uneventful. Muscular weakness improvement achieved immediately after operation. And complete neurological recovery achieved at post-operative 48 hours (Figures 1 & 2).

Discussion
Angiolipomas are benign tumors which are usually locate subcutaneously at the extremity, trunk or neck [8]. SAL are uncommon lesions which are usually locate at the thoracic segment and posterior extradural region. SALs constitute 0.14-1.2 % of spinal tumors, 2-3% of extradural tumors. Most common location of SAL is thoracic segment (78%) [7]. In the literature there is debate about the pathophysiology of SAL. Histologically, SAL are considered as hamartoma 6, or duralmesenchymal benign tumor [9,10]. Mesenchymal stem cell may difference into lipoma or angioma. Mesenchymal cell differentiation may occur thought lipoma side or angioma side. The angiolipoma is an intermediate pathological entity of this differentiation [5]. Angiolipoma was first descripted by Howard and Helwig, and they classified this pathology into two sub-groups which are an infiltrative type and an encapsulated type [10]. Several risk factors have been descripted for growth of SAL.
Trauma, inflammatory stimuli and hormonal imbalance are descripted as etiological factor for acute tumor growth in the literature. Increased prevalence of peri-menopause patients is supporting that hormonal imbalance can be etiological risk factor for acute neurological deterioration of SAL as our case [7]. Other potential risk factors for acute neurological deterioration is pregnancy, weight gain and steroid treatment [11]. Hormone dependent and vascular characters of SAL are responsible for intermittent clinical course of remission and aggravation. Expansion of tumor may cause acute onset clinical symptoms due to thrombosis, intratumoralhemorrhage or steal phenomenon [12]. MRI is the most helpful diagnostic tool for SAL. But histopathological examination is essential for certain diagnosis. These tumors are slow growing benign lesions. Histologically, angiolipomas typically consist of two mesenchymal elements: mature adipocytes and thin walled-vessels, a number of which contain fibrin thrombi [13]. Kaposi's sarcoma and angiosarcoma should be considered when a cellular angiolipoma is seen microscopically [14]. Tumor recurrence after surgery reported as 1.1% by literature.
SAL is usually present by progressive neurological deficits [3,7]. Acute paraplegia due to SAL has been reported in only seven cases (Table 1) [9,10,12,[15][16][17]. Pathogenesis of acute paraplegia was due to tumorhemorrhage in the five cases [12,[15][16][17][18]. The underlying cause of tumorhemorrhage has hypothesized as increased blood flow due to exercise by some authors Tsutsumi, et al. [12,15]has been reported acute onset paraplegia of SAL case. The underlying cause of tumorhemorrhage has been reported as disruption of abnormal vessels by increased venous pressure due to pregnancy. Other hypotheses about acute onset symptoms are hemorrhage due to abnormal arterial vessel injury [15,16] reported acute onset paraplegia caused by tumorhemorrhage due to antiplatelet therapy. In our case there was not tumorhemorrhage. But patient had weight gain due to immobilization because of lumbar stabilization operation and back pain. Spinal cord decompression is mandatory for acute onset neurological findings. When there is no neurological finding follow-up with radiological and clinical examination can be option. In previous cases complete neurological improvement after decompression within 48 hours achieved in four cases as our case [10,12,15,16]. In a previous cases, tumor was consist of adipose tissue and abnormal small vascular structures [12,[15][16][17][18][19]. In our case, there is no active bleeding of tumor or abnormal vascular structures.

Conclusion
SAL is a rare entity which is composed of adipose tissue and vascular elements. Any factors that can creates alteration of hemodynamic status or adipose tissue may cause acute neurological finding. MRI is essential diagnostic tool for these lesions. Postoperative outcomes are excellent even at the complete paraplegia and subtotal resection.