The vertebral arch subcutaneous node refers to a lesion confined to the pedicle, lamina, spinous process, or transverse process, rather than secondary to the extension of a vertebral body subcutaneous node to the pedicle, transverse process, or superior and inferior articular processes. This condition is relatively rare, accounting for 0.8–1% of spinal subcutaneous nodes. In another series of 10,531 spinal subcutaneous node cases, 45 were reported, representing 2.3%. Among 3,139 spinal subcutaneous node cases at the Beijing subcutaneous node disease prevention and treatment center, only 17 cases were documented, accounting for 0.4%. The low incidence rate is attributed by Guo Juling to factors such as the rich anastomosis of small stirred pulses in the vertebral arch, which reduces the likelihood of embolism, its non-weight-bearing nature, the scarcity of local cancellous bone, and the abundance of surrounding muscles.

bubble_chart Clinical Manifestations

1. There is a significant difference in the incidence between males and females, and it is more common in young adults. Systemic symptoms are often not obvious. The most common site of occurrence is the thoracic spine, followed by the lumbar and cervical spine. The lesions often surround the spinal cord on three sides of the thoracic vertebral arch, with spinal cord compression coming from the posterior side. As a result, 25–50% of cases are complicated by paraplegia, which is a higher frequency than that of subcutaneous nodules of the vertebral body. In addition to pain at the affected site, radiating nerve root pain is also relatively common.

2. The lesions are close to the body surface, and the course of the disease is shorter than that of spinal subcutaneous nodules. They are located near the midline of the spine and often present with masses, abscesses, or sinuses. There is no spinal deformity, and movement is not significantly restricted.

1. X-ray imaging: Anteroposterior X-ray of the spine may also include oblique views when necessary. The manifestations are described as follows:

(1) Pedicle lesions: Asymmetric osteolytic destruction with blurred circular or elliptical shadows above the spinous process on both sides of the upper vertebral body.

(2) Lamina lesions: Reduced bone density on both sides of the spinous process.

(3) Spinous process lesions: Partial or complete shadow disappearance of the original spinous process compared to adjacent normal spinous processes.

2. CT scanning: Utilizing the high resolution of CT, even subtle destruction of the pedicle can be detected.

bubble_chart Diagnosis

The diagnosis can be made based on medical history, signs, and X-ray findings, supplemented by CT when necessary. However, early cases without paravertebral abscesses and sinuses, or lesions in other subcutaneous nodes, are more difficult to diagnose.

bubble_chart Treatment Measures

1. Patients without concurrent paraplegia or sinus can be cured with medication alone; otherwise, surgical treatment is adopted.

2. Surgical procedure: For lesions of the spinous process, lamina, and articular process, a posterior midline incision can be used. After separating the paravertebral sacrospinalis muscle, the lesion can be reached. For lesions of the transverse process and pedicle, a paramedian incision can be made, with an approach similar to that of costotransversectomy.

bubble_chart Differentiation

1. Metastatic carcinoma Older age, more common in vertebral bodies, can also invade the pedicles. X-ray shows mainly osteolytic destruction, while prostate cancer and breast cancer metastases may present as osteoblastic changes.

3. Spinal cord tumors Extradural tumors in the spinal canal are often neurofibromas, compressing surrounding bone and causing marginal bone destruction. As the tumor enlarges, it may involve the pedicles and later extend to the ipsilateral rib head or lamina.

4. Acute suppurative inflammation Often presents with acute onset, high fever, and severe pain. Local acute inflammatory manifestations are evident. X-ray reveals extensive lesions, commonly with bone sclerosis. {|103|}