¹⁸F-FDG PET/CT and MRI findings of an atypical glomus tumor of the thoracic spine: a rare case report

Abstract

Background

Glomus tumors (glomangiomas) are rare mesenchymal neoplasms derived from modified smooth muscle cells of the glomus body. Since they most commonly occur in the subungual regions of the extremities, primary involvement of the spine is exceedingly rare, particularly in atypical variants with borderline biological behavior.

Case presentation

A 61-year-old man presented with a long-standing history of intermittent back pain that had recently worsened. Magnetic resonance imaging revealed a solid lesion involving the T10–T11 vertebral region with intermediate T1 signal intensity, mildly hypointense T2 signal, intralesional hemorrhagic foci, and marked heterogeneous enhancement causing spinal canal stenosis. ¹⁸F-FDG PET/CT demonstrated mild to moderate focal radiotracer uptake (SUVmax 5.6) corresponding to the spinal lesion, without evidence of other FDG-avid lesions suggestive of a primary malignancy or metastatic disease. Surgical resection was primarily indicated based on progressive symptoms and MRI findings; PET/CT findings did not alter the surgical decision but provided additional staging information, and histopathological examination established the diagnosis of an atypical glomus tumor.

Conclusion

This case highlights the complementary role of MRI and ¹⁸F-FDG PET/CT in the evaluation of rare spinal glomus tumors. ¹⁸F-FDG PET/CT may provide supportive metabolic information and help assess the presence of additional FDG-avid lesions in atypical presentations.

Introduction

Glomus tumors (glomangiomas) are uncommon mesenchymal neoplasms derived from modified smooth muscle cells of the glomus body and typically arise in the subungual regions of the extremities (Mravic et al. 2015; Folpe et al. 2001). Extra-digital and deep-seated glomus tumors are rare and may occur in unusual locations, including bone and visceral organs.

Primary involvement of the spine is exceedingly uncommon, with only a limited number of cases reported in the literature (Li and Zheng 2021; Li et al. 2021). Atypical glomus tumors, characterized by deep location or histological features suggestive of borderline biological behavior, may pose diagnostic challenges because their imaging findings can overlap with those of other spinal neoplasms (WHO Classification of Tumours Editorial Board 2020). We present a rare case of an atypical thoracic spinal glomus tumor, with emphasis on its MRI and ¹⁸F-FDG PET/CT findings.

Case presentation

A 61-year-old man presented with a long-standing history of intermittent thoracic back pain that had gradually worsened over several months. Neurological examination revealed no focal deficits.

MRI demonstrated a well-defined lesion involving the T10–T11 vertebral region. The lesion showed intermediate signal intensity on T1-weighted images, mildly hypointense signal on T2-weighted images, and punctate hyperintense foci on T1-weighted fat-suppressed images, suggestive of intralesional hemorrhage. Marked heterogeneous enhancement was observed after contrast administration, resulting in spinal canal stenosis without intervertebral disc involvement (Fig. 1).

Fig. 1.

MRI findings of the thoracic spine. Sagittal non-contrast, non-fat-suppressed T1-weighted images (A, B) demonstrate a solid lesion involving the T10–T11 vertebral region with intermediate signal intensity and multiple punctate hyperintense foci at the posterior margin and spinous process (arrows). Sagittal fat-suppressed T1-weighted image (C) shows persistent hyperintensity of these foci, suggesting intralesional hemorrhage rather than fatty components. Sagittal fat-suppressed T2-weighted image (D) reveals a mildly hypointense solid mass extending into the spinal canal, resulting in significant canal stenosis. Post-contrast fat-suppressed T1-weighted images (E, F) demonstrate marked heterogeneous enhancement, consistent with a hypervascular lesion. Axial pre-contrast fat-suppressed T1-weighted image (G) shows mild anterior perilesional edema. Coronal post-contrast fat-suppressed T1-weighted image (H) further delineates the extent of enhancement and paravertebral soft tissue involvement

¹⁸F-FDG PET/CT was performed to assess metabolic activity and to evaluate the presence of additional FDG-avid lesions. The examination demonstrated mild to moderate focal radiotracer uptake (SUVmax 5.6) corresponding to the thoracic spinal lesion, without evidence of other FDG-avid lesions suggestive of a primary malignancy or metastatic disease elsewhere in the body (Fig. 2).

Fig. 2.

18F-FDG PET/CT findings. Maximum intensity projection image (A) demonstrates focal increased FDG uptake in the lower thoracic spine (arrow). Transaxial PET image (B) shows focal radiotracer uptake corresponding to the T10–T11 vertebral region. Sagittal and coronal PET images (C, D) further localize the hypermetabolic lesion. Axial, sagittal, and coronal CT images (E–J) demonstrate an osteolytic lesion involving the T10–T11 vertebral bodies with cortical destruction and extension into the spinal canal. Fused PET/CT images (K–M) confirm focal FDG uptake localized to the T10–T11 lesion (arrows), with a maximum standardized uptake value (SUVmax) of 5.6. No abnormal FDG uptake suggestive of distant metastatic disease is identified on whole-body PET/CT imaging

The patient subsequently underwent surgical resection, and histopathological examination confirmed the diagnosis of an atypical glomus tumor (Fig. 3).

Fig. 3.

Histopathological findings. (A) Gross appearance of the resected lesion showing red-brown, soft, fragmented tissue spread over a measuring pad (large grid ≈ 1 cm; small grid ≈ 5 mm). (B) Low-power photomicrograph (H&E stain, ×4) demonstrating diffuse growth of tumor cells with focal vascular lumina (circled), showing an indistinct interface with adjacent tissue. Scale bar = 1 mm. (C) Intermediate-power view (H&E stain, ×10) showing uniform round tumor cells with mild-to-moderate nuclear atypia arranged in a dense and even distribution. Scale bar = 200 μm. (D) Intermediate-power view (H&E stain, ×10) demonstrating a diffuse growth pattern with infrequent mitotic figures (approximately 5 per 50 high-power fields) and no evidence of necrosis or lymphovascular invasion. Scale bar = 200 μm

Discussion

Glomus tumors (glomangiomas) are generally considered benign; however, deep-seated or extra-digital lesions may exhibit atypical features and borderline biological behavior. Primary spinal glomus tumors are exceedingly rare, and their clinical and imaging manifestations are often nonspecific, which can complicate preoperative diagnosis (Glazebrook et al. 2011). In the present case, MRI demonstrated imaging features suggestive of a vascular-origin tumor, including marked heterogeneous enhancement and intralesional hemorrhagic foci. Mild T2 hypointensity may reflect relatively high cellularity, while the absence of intervertebral disc involvement and destructive osseous changes argued against aggressive malignancy or infection. These findings are consistent with previously reported imaging characteristics of glomus tumors at uncommon sites (Kransdorf et al. 2025).

¹⁸F-FDG PET/CT is not routinely performed for glomus tumors but may provide complementary metabolic information in selected cases. In this patient, the spinal lesion demonstrated mild to moderate FDG uptake, consistent with the low-to-intermediate metabolic activity typically reported for glomus tumors. The absence of additional FDG-avid lesions argued against an FDG-avid primary malignancy or metastatic disease.

Previous studies have shown that FDG uptake in glomus tumors is variable and more closely related to tumor vascularity and cellularity than to malignant potential (Dong et al. 2015; Seban et al. 2020). In the present case, the observed FDG uptake can be plausibly attributed to the tumor’s rich vascularity and intratumoral hemorrhage, which may increase local metabolic activity through inflammatory response and enhanced vascular permeability. Although the tumor was classified as atypical with malignant potential, the lack of overtly malignant histological features, such as extensive necrosis or high mitotic activity, likely explains the relatively limited FDG avidity. Overall, these findings suggest that FDG uptake reflected vascular and hemorrhagic characteristics rather than frank malignancy, supporting the role of ¹⁸F-FDG PET/CT as an adjunct to, but not a substitute for, histopathological diagnosis.

Conclusion

We report a rare case of an atypical glomus tumor of the thoracic spine evaluated using multimodal imaging. MRI and ¹⁸F-FDG PET/CT provided complementary anatomical and metabolic information that aided lesion characterization and absence of additional FDG-avid lesions. Awareness of this rare entity may help improve diagnostic confidence in similar cases.

Author contributions

XZ and ZW contributed to data collection and manuscript drafting. XM and YW contributed to imaging analysis and interpretation. JQ and ZL contributed to pathological evaluation and literature review. WF supervised the study and critically revised the manuscript. All authors read and approved the final manuscript.

Funding

This study received no specific funding from any public, commercial, or not-for-profit funding agencies.

Data availability

The data supporting the findings of this study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

This study was conducted in accordance with the Declaration of Helsinki. Ethical approval was waived by the institutional review board due to the retrospective nature of this single case report.

Consent for publication

Written informed consent was obtained from the patient for publication of this case report and the accompanying images.

Competing interests

The authors declare that they have no competing interests.