VHs are common benign lesions characterized by proliferating blood vessels. They are considered dysemryogenic or hamartomatous in origin. Perman first described the radiographic features of typical VHs in 1926 [2]. The prevalence of VH is approximately 11% in adults [3]. The prevalence of hemangiomas seems to increase with age.
The vast majority of VHs are asymptomatic and quiescent. They are usually found incidentally on MRI or CT. VHs are most frequent in the thoracic spine, followed by the lumbar and cervical spine; sacral involvement is rare [1]. Multilevel involvement occurs in up to 30% of cases. Although they are usually confined to the vertebral body, extension into the posterior elements may occur.
Plain radiography may reveal either parallel linear streaks or a “honeycomb” appearance. CT can also demonstrate the classic ‘‘honeycomb’’ sign or vertically oriented vertebral lucencies separated by thickened trabecular bone. Typical VHs with predominant fat appear as well-defined hyperintense lesions on T1- and T2-weighted imaging.
VHs can grow quickly to extend beyond the vertebral cortex into the paravertebral and/or epidural space where they may compress the spinal cord and/or nerve roots. These lesions are called aggressive VHs [4] and may present with myelopathy, cauda equina syndrome, or radiculopathy. The usual presenting symptoms are lower extremity numbness associated with progressive motor weakness; sphincteric disturbance occurs late [5, 6].
Atypical VHs have less fat but higher vascular content than typical ones [4]. In 2019, Wang et al. [1] summarized imaging characteristics of aggressive VHs and described the following as atypical features: (1) expansive and osteolytic vertebral bony destruction; (2) vertebral compression fractures; (3) multilevel involvement or longitudinal soft tissue extension greater than one segment; (4) epidural soft tissue compressing the spinal cord; (4) predominant involvement of the lamina and/or pedicle; and (5) atypical MRI signals. In their study, 36% of aggressive VHs exhibited atypical findings; only one lesion was located in the sacrum. Their review of the literature over the previous 20 years revealed 45 atypical aggressive VHs.
Our patient had an aggressive VH that originated in the sacrum and exhibited atypical features. This lesion showed osteolytic bony destruction and did not have a “honeycomb” appearance or “polka-dot sign.” It was isointense on T1-weighted imaging, hyperintense on T2-weighted imaging, and heterogeneously enhanced. The superior vertebral endplate of S1 was clearly interrupted on sagittal MRI. The lesion occupied all of S1 and involved the posterior aspect of S2. Epidural osseous compression caused symptoms of radiculopathy. Therefore, 5 radiological atypical features were present.
Decompression with laminectomy should be performed in patients with rapid and progressive neurological deficit. Reported cure rates of laminectomy for VHs without extraosseous soft tissue extension range from 70–80% [7, 8]. Frank et al. [9] reported six VH patients who underwent decompressive laminectomy; among these, two experienced recurrence and required reoperation. For aggressive VHs that cause cord compression and neurological deficit, more radical surgical resection has been advocated. The reported rates of recurrence after resection of aggressive VHs vary between studies. Goldstein et al. [10] reported two recurrences in 68 patients; the time to recurrence after surgery was 4.4 and 5.3 years, respectively. In a retrospective review of 20 patients treated for aggressive VHs, three had undergone surgical decompression at other institutions [11]. Therefore, recurrence of aggressive VHs after resection depends on not only lesion extension but also the experience of the operator. Our patient experienced recurrence 6 months after surgery and presented with worsening lower back pain. MRI showed an increase in soft tissue mass size and severe thecal sac compression.
According to the aggressive VHs with atypical radiological features are uncommon, accurate diagnosis before operation is challenge for radiologist. The lesions with sclerotic margin can differentiated from the most majority of malignance bone tumours. Aggressive VHs grow slowly because of the nature. Furthermore, familiar with atypical radiological features of aggressive VHs summarized by Wang et al [1] may provide clues for diagnosis. Biopsy is inevitable for some patients which may not make the final diagnosis and only revealed necrosis tissue and bone tissue.
The differential diagnosis of VH includes metastasis, solitary plasmacytoma, and epithelioid hemangioendothelioma. Osteolytic vertebral metastases may present with cortical expansion and associated soft tissue mass. Definitive diagnosis can be difficult and often requires multiple imaging modalities in addition to histopathological examination [12]. The classic radiological appearance of solitary bone plasmocytoma has been described as a “mini brain” appearance on axial CT and MRI. However, one-third of cases may mimic aggressive VH, which makes accurate diagnosis challenging [12]. Epithelioid hemangioendothelioma is a rare mesenchymal neoplasm that shows a lytic pattern of bony destruction on CT with mixed signal intensity on T1- and T2-weighted imaging.