|Year : 2018 | Volume
| Issue : 2 | Page : 447-450
Bone metastases without primary tumor: A well-differentiated follicular thyroid carcinoma case
Adil Boz1, Gokhan Tazegul2, Humeyra Bozoglan3, Ozlem Dogan3, Ramazan Sari3, Hasan Ali Altunbas3, Cumhur Arici4, Guzide Ayse Ocak5, Mustafa Kemal Balci3
1 Department of Nuclear Medicine, Faculty of Medicine, Akdeniz University, Antalya, Turkey
2 Department of Internal Medicine, Faculty of Medicine, Akdeniz University, Antalya, Turkey
3 Department of Endocrinology, Faculty of Medicine, Akdeniz University, Antalya, Turkey
4 Department of General Surgery, Faculty of Medicine, Akdeniz University, Antalya, Turkey
5 Department of Pathology, Faculty of Medicine, Akdeniz University, Antalya, Turkey
|Date of Web Publication||8-Mar-2018|
Dr. Gokhan Tazegul
Department of Internal Medicine, Faculty of Medicine, Akdeniz University, Antalya
Source of Support: None, Conflict of Interest: None
Metastases to the bone are the most common malignant bone tumors. Prostate, breast, and lung carcinomas are the most common primaries of bone metastases. Bone metastases show poor prognosis in means of median survival; however, some patients with highly curable tumors such as thyroid carcinoma may benefit from treatment. We report and discuss a unique case of a 70-year-old female patient presenting with arm pain, diagnosed with metastatic well-differentiated follicular carcinoma without a primary tumor in the thyroid.
Keywords: Bone metastases, thyroid carcinoma, thyroid neoplasms, thyroid nodule
|How to cite this article:|
Boz A, Tazegul G, Bozoglan H, Dogan O, Sari R, Altunbas HA, Arici C, Ocak GA, Balci MK. Bone metastases without primary tumor: A well-differentiated follicular thyroid carcinoma case. J Can Res Ther 2018;14:447-50
|How to cite this URL:|
Boz A, Tazegul G, Bozoglan H, Dogan O, Sari R, Altunbas HA, Arici C, Ocak GA, Balci MK. Bone metastases without primary tumor: A well-differentiated follicular thyroid carcinoma case. J Can Res Ther [serial online] 2018 [cited 2020 Jul 13];14:447-50. Available from: http://www.cancerjournal.net/text.asp?2018/14/2/447/199391
| > Introduction|| |
Metastases are the most common malignant bone tumors. Thyroid carcinoma may present with asymptomatic bone metastases and should be considered among the potential differential diagnoses. Nearly 7%–23% of the patients with thyroid carcinomas may develop metastases during disease progression; however, only 1%–3% of patients present with distant metastatic lesions. Bone metastases show poor prognosis, and some patients with highly curable tumors benefit from treatment. Early diagnosis and complete resection of metastatic lesions are important. We report and discuss a unique case of a 70-year-old female patient presenting with arm pain, diagnosed with metastatic well-differentiated follicular carcinoma without a primary tumor in the thyroid.
| > Case Report|| |
A 70-year-old female admitted with constant pain localized to her right arm. She states a dull pain which started few months earlier, located on her right arm, and it was only partially alleviated by nonsteroidal anti-inflammatory drugs. On her medical history, she had hypertension. The patient had no neuromuscular deficit in her right arm, and she was visibly discomforted when her right arm was squeezed. Chest X-ray revealed a lytic bone mass along the humerus shaft [Figure 1]. Blood count, blood biochemistry, and tumor markers were within normal range. Positron emission tomography/computed tomography (PET/CT) was performed to distinguish any metastatic malignant process. On PET/CT, a hypermetabolic diaphyseal mass on the right humerus (SUVmax: 5) was seen, and there was no abnormal glucose uptake in other areas [Figure 2] and [Figure 3]. No pathologic uptake was seen on PET scan, and the thyroid gland was seen as nodular and hyperplastic on CT. Thyroid functions tests were within normal limits. The patient was referred to orthopedic surgery, and she underwent sampling and internal fixation for the humerus. Sampling of the tumor revealed follicular-like cells with colloid in their lumen resembling thyroid follicles [Figure 4]. Tumor cells were thyroid transcription factor 1, vimentin, Pan-CK, and thyroglobulin positive [Figure 5]. The patient was diagnosed as metastatic follicular thyroid carcinoma and was referred to general surgery for total thyroidectomy. The patient underwent total thyroidectomy; however, pathology failed to demonstrate a malignant focus, and only degenerative nodular hyperplasia was seen. Nonsteroidal anti-inflammatory treatment and L-thyroxine replacement were given after surgery. The patient received 200 mCi of iodine-131 (I-131) 3 months postoperatively. On 6-month follow-up, the patient complained of a dull pain localized to her right hip, whole body iodine screen after high-dose I-131 admission revealed a new metastatic focus on the head of the right femur [Figure 6].
|Figure 1: Posterior-anterior chest X-ray revealed a lytic bone mass along the right humerus shaft|
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|Figure 2: Serial positron emission tomography/computed tomography images showing diaphyseal mass on the right humerus with 2-fluoro-2-deoxy-D-glucose uptake|
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|Figure 3: On three-dimensional reconstruction, tumoral invasion of the humerus can be clearly seen|
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|Figure 4: Tumoral lesion demonstrating thyroid follicle-like cells forming follicles with colloid in their lumen (H and E, ×100)|
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|Figure 6: On follow-up, a new metastatic focus was revealed on the head of the right femur|
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| > Discussion|| |
Metastatic tumors of the bone are the most common malignant tumor involving bone. Most common metastatic tumors to the bone are prostate, breast, and lung carcinomas. Skeletal metastases may be the first sign of malignancy in nearly a quarter of cases. In a study investigating primary tumors of bone metastases, authors were able to identify primary tumors in 79% of all cases. They stated that bone biopsy is a key component of diagnostic strategy along with extraosseous biopsies. However, nearly another quarter of bone metastases have no primary tumors. As discussed previously by Siddiq et al., bone metastases from primary tumors of unknown origin are commonly attributed to prostate, breast, or lung carcinomas; however, thyroid carcinoma may present with asymptomatic bone metastases and should be considered among the potential differential diagnoses.
Thyroid carcinomas constitute 1% of all malignant neoplasms. They are highly treatable and rarely tend to be aggressive. Age at diagnosis, gender, lesion size, capsular and vascular invasion, and distant metastases are important prognostic factors. Most common sites of metastasis of thyroid carcinomas are lymph nodes, lungs, and bones. Well-differentiated papillary carcinomas tend to spread lymphatically, whereas follicular carcinomas spread hematogenously to lungs and bones. Nearly 7%–23% of the patients may develop metastases during the disease course; however, only 1%–3% of patients present with distant metastatic lesions. In their study, Wu et al. demonstrated only 5% of patients with thyroid carcinoma in a 10-year period had developed bone metastases. Pain was the presenting symptoms in 25 (56.8%) patients out of 44 and 23 patients (52.2%) out of 44 presented with bone metastases before the thyroid cancers were diagnosed.
Bone metastases show poor prognosis in means of median survival; however, some patients with highly curable tumors may benefit from treatment, such as thyroid cancer, neuroblastoma, germ cell carcinomas, and colon carcinoma. Radical treatment in these patients proves to be most notably effective if patients have one or two bone metastases. Differentiated thyroid carcinomas are slowly progressive, and 10-year survival rates are around 90%; however, bone metastatic thyroid carcinomas have poor prognosis with 0%–34% of 10-year survival rates. Therefore, early diagnosis and complete resection of metastatic lesions are of import. Indications for surgical intervention of bone metastasis of thyroid carcinomas are continuous pain, solitary metastasis, refractory to treatment, high risk of fracture or paraplegia, and obvious manifestation of neurothlipsis whereas multiple organ metastasis and poor performance are contraindications for surgery. In a cohort by Pittas et al., radioiodine uptake and the absence of extraosseous metastases were the factors best predicted survival in bone metastatic thyroid carcinomas. Limited metastatic disease and Hürthle cell subtype were favorable for survival; however, survival did not change between patients with a single metastatic site and multiple lesions.
Metastatic tumors without primary tumor in thyroid gland have been rarely documented. Follicular carcinomas cannot be distinguished from normal tissue with fine-needle aspiration cytology; therefore, resection of the thyroid gland is needed to identify the primary tumor. Ban et al. identified three patients with metastatic follicular thyroid carcinoma with no characteristic lesions in the thyroid gland. One patient had solitary follicular lesion, another had single atypical adenoma in multinodular goiter, and the last patient had multinodular thyroid parenchyma and extensive fibrosis. Of three patients, two had lung, two had bone, and two had soft-tissue metastases.
Although most patients may present with synchronous metastatic lesions with primary thyroid tumors, some patients develop metachronous lesions even after a decade of initial treatment of primary tumor. This remaining occult disease may survive subclinically without elevated thyroglobulin levels for long periods of time, and this dormant state may change from patient to patient, and clinicians should be aware of this dormancy. We hypothesize, in light of this case, metastases of follicular thyroid carcinomas may arise without primary tumors in the thyroid gland probably due to regression of the primary tumor. Further studies are needed to recognize and understand this metastatic pattern of follicular thyroid carcinomas.
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Conflicts of interest
There are no conflicts of interest.
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