Papillary thyroid carcinoma is usually presented with a thyroid nodule or cervical lymph node enlargement. Presentation of papillary thyroid carcinoma with distant metastasis is rare. This is a case report of a case of papillary thyroid carcinoma of the follicular variety presenting with L3-4 metastases with back pain.
The pathogenicity of thyroid cancer varies according to type whether differentiated (papillary) or undifferentiated or anaplastic. Thyroid cancer represents 1% of cancer cases in the US, yet, thyroid cancer is the commonest endocrine cancer. Papillary thyroid cancer represents about 88% of all thyroid cancers (Anand and others, 2008). Histological varieties vary in different areas with different iodine uptake evidenced by higher incidence in Austria and Germany compared to the US and Italy (Paunovic, 2003). The outstanding clinical characteristics of papillary thyroid cancer are multiple tumor formation (multicentricity), and cervical lymph node metastasis (Ito, and Miyauchi, 2005). This report discusses a case of papillary thyroid carcinoma (follicular variant) presenting with low back pain because of spine metastasis at lumbar 3-4 level. About 15 to 30% of thyroid cancer patients develop osteolytic bone metastasis with the overwhelming outcome of rigorous pain, pathological fractures, spinal cord compression, and serious hypocalcemia. The osteolytic (bone destroying) nature of metastasis is because of osteoclastic activity, not the tumor cells. The biological factors accountable for osteoclastic activity vary with the type of tumor (Roodman, 2004).
WP is a 54-year-old male patient with no significant past medical history and presents with complaints of low back pain for the last few weeks worsening until it cannot be tolerated. The patient denies any fever or chills or weakness, numbness in the extremities. The patient complained neither of losing weight nor abdominal pain. Bowel bladder habits were within normal limits. The patient had L5-S1 surgery 8 years ago. The patient is a coach and teacher with no history of tobacco, alcohol, or illicit drug abuse. Vital signs are stable. Heart lungs are within normal limits. The lumbar spine reveals no tenderness although the range of motion was decreased. No focal neurological deficits. MRI of the lumbar spine showed an expansile tumor affecting L3 and L4. The patient had the mass removed with spinal surgery by an orthopedic surgeon. The pathology report showed metastatic thyroid cancer possibly a follicular variant. Subsequently, further imaging studies showed thyroid nodule and C3 body lytic lesions. Later the patient had a biopsy of thyroid and cervical lymph nodes which showed metastatic papillary carcinoma, a follicular variant with intravascular spread. Later patient had a total thyroidectomy with right paratracheal node dissection. Later patient had to post operative radioactive iodine therapy to eradicate residual cancer. The patient remained on thyroid replacement patient has been clinically stable.
Well, differentiated thyroid carcinoma includes papillary, follicular, and Hurthle cell thyroid carcinoma Schlumberger (2004). The follicular type has the same prognosis as the regular papillary thyroid carcinoma. In addition, in many cases, metastases show the typical papillary histopathologic pattern (Sheils, 2005). Nevertheless, there are some differences in tumor genotype-specific for the follicular variant that may explain the differences in tumor phenotype described in some literature about this tumor (Salajegheh, 2008).
Fine needle aspiration biopsy surpassed radionuclide scan and ultrasound imaging as the first test to investigate a thyroid nodule. Spread of malignant cells has been reported in thyroid cancer fine needle biopsy, although less common than with abdominal and pelvic malignancies. The possibility relates to the needle gauge, the number of needle passes, and needle withdrawal without suction release. The needle recommended for thyroid fine needle biopsy is 22, and the number of needle passes is between 1-10 (Tamiolakis and others, 2006).
Sreedharan and others (2007) reported four cases of follicular thyroid carcinoma presented with axial skeletal metastases. All cases were over 45 years; tumors were either in the skull or lumbosacral spine. Two other studies; Court and others (2000), and Saillant and others (1995), both after Sreedharan and others (2007) reported axial skeletal metastases at the iliolumbosacral angle. The authors suggested adding serum anti-thyroid transcription factor-1 fine needle biopsy or an excision biopsy as it helps to differentiate lung and thyroid malignancies from other types.
Based on the report of the American Joint Committee on Cancer (2006), the TNM classification for this case is stage 4 C (T any, N any, and M1). Based on the NCCN (National Comprehensive Cancer Network) clinical practice guidelines on thyroid carcinoma, neurosurgical resection of a skeletal metastasis is indicated in symptomatic metastases or asymptomatic metastases in weight-bearing extremities. Surgical removal is also considered in enlarging tumors producing symptoms. As the clinical staging of the case is stage 4 C, therefore, total thyroidectomy is not indicated. Alternatives to excision are radioiodine treatment, bisphosphonate treatment, or embolization of the tumor (NCCN, 2008).
Although the papillary thyroid carcinoma metastasizes through lymphatics to regional lymph nodes, the incidence of distant metastases in cases of papillary thyroid cancer is less than 10% of cases in some studies (Durante and others, 2006). Other studies suggest that distant metastasis occurs in less than 5% of cases, in these cases metastases are usually in the lungs. Follicular thyroid carcinoma (alternatively known as Hurthle cell carcinoma) spread primarily to the bones, lungs, or CNS and not to lymph nodes. Therefore, the presentation of papillary thyroid carcinoma with axial skeletal distant metastasis is a rarity (Ridgway, n.d.) Radioiodine I is the treatment of choice, although adjuvant beam radiation treatment or adjuvant surgeries are indicated in selected cases. Treatment with Radioiodine I131 until any uptake disappears (Durante and others, 2006).
Siironen (2005) inferred that the most important prognostic factors that significantly relate to survival are age over 45 years, tumor size more than 4 cm, lymph node metastases, and distant metastasis. The author suggested tailoring the initial treatment and follow-up visits according to these factors.
Mr. WP represents few unfavorable prognostic factors, namely age over 45, presence of nodal and distant metastases (stage 4 C). Therefore he may need a total body scan, serum Tg (thyroglobulin), which is a glycoprotein produced by either normal or malignant thyroid cells. Tg production is dependent on TSH, therefore, TSH level should be considered when interpreting Tg value. Neck ultrasonography was performed to determine the size of the thyroid nodule and to detect lymph nodes’ possible involvement. Adjuvant treatment whether radiotherapy or surgery is considered accordingly. During follow-up visits, clinical neurological examination is performed to detect neurological deficits. Follow-up visits are planned in 3-6 months duration (Schlumberger, 2004).
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