|Year : 2021 | Volume
| Issue : 1 | Page : 28-30
An unusual case of vertebral metastasis as initial presentation of follicular thyroid carcinoma complicated with misplaced pedicle screw
Lakshay Raheja1, R Krishnakumar2
1 Department of Neurosurgery, Medical Trust Hospital, Kochi, Kerala, India
2 Department of Spine Surgery, Medical Trust Hospital, Kochi, Kerala, India
|Date of Submission||03-Jun-2021|
|Date of Decision||09-Jul-2021|
|Date of Acceptance||10-Jul-2021|
|Date of Web Publication||25-Jul-2021|
Department of Neurosurgery, Medical Trust Hospital, M. G. Road, Kochi - 682 016, Kerala
Source of Support: None, Conflict of Interest: None
Vertebral metastasis as initial presentation for follicular thyroid carcinomas is rare and requires proactive management to minimize disability considering a good associated long-term survival. A review of literature in 2019 noted 27 such cases – most of the patients had solitary vertebral metastases or multiple adjacent level involvement. Surgical treatment in such cases is usually based on the extent of fractures or neural compression in the form of decompression, debulking, or total en bloc resection and biopsy. Pedicle screw placement has been studied in several large studies, and clinically relevant misplacement is rare and revision may be required. We present a case where a patient with a pathological fracture previously evaluated and operated came to us with radiculopathy caused by metastatic mass lesion and a misplaced pedicle screw.
Keywords: Follicular thyroid carcinoma, misplaced pedicle screw, spine metastasis
|How to cite this article:|
Raheja L, Krishnakumar R. An unusual case of vertebral metastasis as initial presentation of follicular thyroid carcinoma complicated with misplaced pedicle screw. J Orthop Assoc South Indian States 2021;18:28-30
|How to cite this URL:|
Raheja L, Krishnakumar R. An unusual case of vertebral metastasis as initial presentation of follicular thyroid carcinoma complicated with misplaced pedicle screw. J Orthop Assoc South Indian States [serial online] 2021 [cited 2021 Dec 9];18:28-30. Available from: https://www.joasis.org/text.asp?2021/18/1/28/322300
| Introduction|| |
Differentiated thyroid cancer (DTC) includes papillary, Hurthle cell, and follicular thyroid carcinomas (FTCs) and is usually associated with good prognosis and long-term survival rate. FTC has a higher rate of bony metastasis – there is bone involvement in 7%–12% of the cases with FTC, and the most frequently involved region is spinal column. However, spinal metastasis as the initial presentation of FTC is rare. Treatment protocol is usually focused on the establishment of histopathological diagnosis, stabilization, and decompression of neural elements followed by radiotherapy/radioactive iodine. This is a case report of a patient previously operated for pathological fracture of lumbar spine with uncertain tissue diagnosis and a misplaced pedicle screw presenting as radicular pain.
| Case Report|| |
A 50-year-old female, with a past history of subtotal thyroidectomy (indication – unknown) 15 years ago, was initially managed for complaints of low back pain with right lower-limb radiation for 2 months at another center. Initial magnetic resonance imaging of the lumbar spine revealed T1/T2 hypointense lesion causing the collapse of L2 vertebral body with compression of the thecal sac and bilateral foramina and a small L5 vertebral body lesion. Multiple myeloma workup was negative. Computed tomography-guided biopsy from the L2 vertebral body revealed sparsely cellular small groups of epithelial cells with moderate quantity of cytoplasm and uniform nuclei, suggestive of metastasis from thyroid malignancy. Fine-needle aspiration cytology (FNAC) from the thyroid was suggestive of benign lesion – Bethesda 2. Fluorodeoxyglucose-positron emission tomography scan done for primary was suggestive of benign thyroid nodules in both lobes. She underwent posterolateral instrumentation without decompression in the form of L1–L3 pedicle screw fixation. No further therapy was instituted.
The patient presented to us 9 months postoperatively with progressive radiculopathic pain along the right L2, L3 dermatome. On examination, there were no neurological deficits. Pain was severely debilitating making it difficult for the patient to walk and carry out her routine activities. Further workup revealed L2 vertebral body lesion to have mildly increased in size causing further compression of the thecal sac and bilateral exiting nerve roots [Figure 1]. The L3 right-sided screw was noted to be extrapedicular, entering the L3 vertebral body along the midline through the vertebral canal [Figure 2]. The patient was counseled regarding need for reoperation with the aim of establishing tissue diagnosis, correction of instrumentation, and decompression of spinal canal. With careful precautions, the previous surgical wound was incised and subcutaneous and muscular dissection was done to expose the implants. L2, L3 laminectomy was done, and a large, friable, highly vascular mass was noted to have replaced the L2 vertebral body with encasement of the right L2 nerve root [Figure 3]. Sample for biopsy and culture/sensitivity was obtained and feasible bilateral debulking was done via transpedicular corridors. The right L3 pedicle screw, inserted through the facet joint and passing between the thecal sac and the nerve root (axilla), was removed [Figure 4]. No inadvertent durotomy was noted. L2, L3 nerve roots were decompressed and the right L3 pedicle screw was correctly placed through the mammillary process. The patient experienced relief of symptoms postoperatively and is now able to carry out her routine activities.
|Figure 1: Magnetic resonance imaging lumbar spine: Initial presentation (left, contrast-enhanced T1) showing an enhancing mass with collapse of L2 vertebra and thecal sac compression; 9 months after initial surgery (right, T2) showing persisting mass lesion. Note that the lesion is slow growing|
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|Figure 2: Computed tomography lumbar spine axial section at L3 level shows right-sided extrapedicular screw to be “totally in the canal”|
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|Figure 3: Intraoperative picture – Fleshy mass (suction tip pointing) as seen after L2 laminectomy and pediculectomy|
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|Figure 4: Intraoperative picture of misplaced right pedicle screw at L3 level|
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Histopathology at our center showed metastatic carcinoma with follicular growth pattern. Repeat FNAC from remnant thyroid nodules revealed FTC. The patient underwent completion thyroidectomy and is planned for radioiodine ablation.
| Discussion|| |
FTC has a higher tendency for bony metastasis due to a predominantly hematological route of spread. FTC may synthesize some substrates providing attachment to bone matrix and promoting bone reabsorption. The rate of bony metastasis of FTC was reported as 7%–20% and the rate of spinal metastasis as 1%–7%., However, FTC presenting as spinal metastasis at the time of diagnosis is rare. A review of literature in 2019 noted only 27 such cases – most of the patients had solitary vertebral metastases or multiple adjacent level involvement.
It was reported that the 10-year survival rate of DTCs was about 80%–95%. Even long-term survival in the cases with distant metastasis during initial presentation was quite high as 44%. In spite of this long survival trend, the presence of spinal metastases causes to reduce the quality of life due to severe pain and/or neurological deficits. The long-term survival in FTC was the reason that allowed for a second chance at diagnosing the lesion in our case.
In a study evaluating the results of total en bloc spondylectomy for spinal metastases of thyroid carcinoma, Demura et al. reported that there was no significant difference between the rate of long survival after total spondylectomy and debulking surgery, however, the rate of local recurrence was significantly higher in the cases treated with debulking surgery than the cases treated with total spondylectomy.
The other interesting aspect of this case was the presence of a misplaced pedicle screw that was noted to be “totally within the canal” leading to radiculopathy. Similar misplaced screws have been reported to cause permanent/delayed neurological deficits, postoperative headache secondary to durotomy, and radiculopathy. While the overall incidence of clinically relevant complications has been noted to be low (~0.5% of all procedures), the incidence is high in case of “totally in the canal” screws. In their study assessing the accuracy of 4790 pedicle screws, Lonstein et al. reported the development of radiculopathy attributable to misplaced pedicle screw to be 0.2%. Such cases benefit from early revision of instrumentation with respect to better neurological recovery or relief of radiculopathy.
| Conclusion|| |
FTC has a high propensity for bony metastases and is usually associated with good long-term survival. FTC with spinal metastases as initial presentation is rare and should be kept in mind when evaluating for spinal neoplasms. Inconclusive/scanty FNAC should prompt repeat FNAC or open biopsy in such cases. “Misplaced” pedicle screws are seldom relevant clinically, more so on medial or inferior breach of pedicles, and depend on the extent of misplacement. Repeat FNAC/open biopsy should be undertaken in case of uncertain tissue diagnosis for planning further therapy. As the long-term survival is good, surgeries in vertebral metastases of FTC must additionally be aimed at relief of neuropathic pain and neurological deficits for improving the functional status of the patient.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]