Glomangiomas, a subset of glomus tumors that have a rich vascular network, are neoplasms of the glomus apparatus. Glomus tumors are benign neoplasms of the perivasculature. They arise from modified smooth muscle cells called glomus cells; they are located in the walls of the Sucquet-Hoyer canal, which is a specialized arterial-venous anastomosis central that controls blood flow for thermal regulation.
Glomus tumors are most commonly present in the subungual region of the finger; other common sites include the palm, wrist, forearm, and foot [1–4]. In fact, it is now recognized that the tumor also develops in sites where a normal glomus body may be sparse or even absent, such as the patella, long bones, stomach, colon, liver, nerves, eyelids, nose, mediastinum, and mesentery [5–12]. A subungual presentation is more common in women; however, no sex predilection is evident at other loci. The male-to-female (M:F) ratio was 1.17:1 in our series. Multiple tumors are more often hereditary and painless; they are more frequent on the arms and have no sex predilection. Multiple lesions may rarely be associated with arteriovenous fistulae, nodular lesions of finger joints, type II multiple endocrine neoplasia, and bone changes such as brachydactyly [13–15].
Glomus tumors are composed of varying proportions of glomus cells, vascular structures, and smooth muscle cells. Depending on the predominant component, there are three variants of glomus tumors. When glomus tumors have prominent glomus cells, poor vasculature, and a scant smooth muscle component, they are classified as solid glomus tumor. Whereas glomus tumors with a prominent vascular component, are classified as glomangiomas. Finally, when there is a prominent smooth muscle component, the tumors are classified as glomangiomyomas. A solid glomus tumor is the most common variant (75%), followed by glomangioma (20%) and glomangiomyoma (5%) . In our series, 2 of 13 cases were deemed to be glomangiomas; the other 11 were solid glomus tumors [17–28].
Microscopically, glomus tumors present as uniformly round-to-ovoid glomus cells arranged as lobules, strands, or broad sheets in a brickwork-like manner. The association with vascular structures includes indistinct capillaries in the walls of the surrounding large blood vessels as well as highly altered vessels. Uniform epithelioid glomus cells with inconspicuous-to-well-defined nucleoli are found between the sinusoidal vessels. Despite their epithelioid appearance and intimate association with vasculature, glomus cells are immunoreactive with vimentin and SMA. However, a small number of these tumors may coexpress myogenic markers and CD34. The current case was immunoreactive with SMA, Vimentin, CD34, PAS, and CD99.
Irrespective of their anatomical location, glomus tumors are usually benign; however, rare malignant cases have been described [29, 30]. Recently, Folpe et al.  proposed a classification of atypical and malignant glomus tumors. Malignant glomus tumors are defined as tumors with: (1) large size (> 2 cm) and deep location, (2) atypical mitotic figures, or (3) nuclear atypia. In contrast, glomus tumors of uncertain malignant potential are superficial in location and show a high mitotic activity, are large in size, or are deeply located. However, in their series of unusual glomus tumors, Folpe et al.  defined the tumor location as either superficial to the peripheral soft tissue or deep to it. In their study, there were 9 deeply located peripheral soft tissue glomus tumors, and all of them were larger than 2 cm; however, only 5 cases metastasized. In a series of 32 gastrointestinal glomus tumors, which by definition were deeply located, only 1 case metastasized, although 19 were larger than 2 cm . In our case review, all of the lesions were > 2cm, and deeply located. The mean follow-up of 13 patients together with the current patient was 20.09 ± 28.43 months (range: 2–90 months); the longest follow-up was 7.5 years. No malignancies had appeared by the conclusion of the follow-up periods. Therefore, the risk of metastases of the deep-seated glomus tumors to the peripheral soft tissue appears to be markedly different from those located in other deep regions. An extracutaneous, deep location should not be considered to be a sign of malignancy. On the basis of these criteria and the lack of atypical mitotic figures, our patient's tumor would be classified as benign. Occasionally, glomus tumors occur in a hereditary manner. The gene has been localized to chromosome 1p21–1p22, which codes for glomulin, a protein thought to play a role in vascularization [33, 34].
The preoperative diagnosis of spinal glomus tumor is very difficult. Usually, the plain radiograph is unremarkable for a spinal glomus tumor. Most patients with a spinal mass undergo a CT scan and magnetic resonance imaging (MRI). Although CT images can show well-defined lesions in a few cases, MR images are considered to be an excellent diagnostic modality. On T1-weighted MR images, glomus tumors may present as a sharply marginated lesion with hypointensity or isointensity, while on T2WIs they are mostly hyperintense. Furthermore, they usually show strong intense enhancement on T1WIs after intravenous administration of gadolinium-DTPA . Most glomus tumors are surrounded by an envelope. T2WI and T1WI after intravenous administration of contrast medium can detect the envelope as a low signal intensity rim. The envelope, which may be incomplete, may be the consequence of a secondary reaction with the surrounding tissue. An envelope-like structure was observed in our case. The MR images of our case are fairly similar to the MR features of the other seven cases. However, a characteristic finding in our case was signal-void fistular lesion in the tumor. The features of the fistular lesion were similar to the images of vascular structures. It also was comparable to the histological findings of tissue with a prominent vascular component. The fistular lesion, due to the direction of flow, was identified on the sagittal images but not on the axial images.
In our case, the differential diagnosis included primary extradural masses or intradural, extramedullary lesions of the spine. Schwannomas, which are the most common extradural tumors, show the typical dumbbell-shaped appearance (extra- and intra-dural portions) in 50% of cases; however, 50% are completely extradural. Schwannomas on MRI images tend to have low signal intensity on T1WI and have brightly increased signal intensity on T2WI due to the high-water content of these lesions. These lesions usually were markedly enhanced following gadolinium administration. The MR findings of the eight cases had similar MR features of the schwannomas, except for the signal-void fistular lesion. Ganglioneuromas and neuroblastomas are tumors of childhood, which often appear with large paraspinal tumor masses.
Choice of therapeutic strategy is predicated according to lesion location and clinical presentation. An overwhelming majority of glomus tumors are benign and are cured by simple local excision. The postsurgical recurrence rate is approximately 10%, because of incomplete removal. In the literature we reviewed, with the longest follow-up being 7.5 years, there was one report of local recurrence because of incomplete removal; however, no malignant transformations, metastases, or deaths occurred by the conclusion of the follow-up period.