|Year : 2014 | Volume
| Issue : 2 | Page : 431-433
A rare case of solitary subcutaneous scalp metastasis from follicular thyroid carcinoma revealed with positron emission tomography/computed tomography: A case report and review
Sait Sager1, Sabire Yilmaz1, Rana Kaya Doner1, Mutlu Niyazoglu2, Metin Halac1, Bedii Kanmaz1
1 Department of Nuclear Medicine, Istanbul University, Cerrahpasa Medical Faculty, Istanbul, Turkey
2 Department of Endocrinology, Istanbul University, Cerrahpasa Medical Faculty, Istanbul, Turkey
|Date of Web Publication||14-Jul-2014|
Department of Nuclear Medicine, Istanbul University, Cerrahpasa Medical Faculty, Cerrahpasa, Fatih, Istanbul
Source of Support: None, Conflict of Interest: None
Differentiated thyroid cancer frequently metastasizes to regional cervical lymph nodes and in advanced cases metastases can be seen in the lungs and skeleton. Metastases to the skin or subcutaneous tissue are rare. Here we present a 49-year-old female patient with solitary scalp metastasis from follicular thyroid carcinoma FTC which was revealed with positron emission tomography (PET)/computed tomography (CT) imaging. PET showed flourodeoxiglucose avid lesion in the left vertex scalp. Scalp lesion was removed totally and histopathological examination revealed well-differentiated thyroid cancer metastasis.
Keywords: Follicular thyroid carcinoma, positron emission tomography/computed tomography scalp metastasis
|How to cite this article:|
Sager S, Yilmaz S, Doner RK, Niyazoglu M, Halac M, Kanmaz B. A rare case of solitary subcutaneous scalp metastasis from follicular thyroid carcinoma revealed with positron emission tomography/computed tomography: A case report and review. J Can Res Ther 2014;10:431-3
|How to cite this URL:|
Sager S, Yilmaz S, Doner RK, Niyazoglu M, Halac M, Kanmaz B. A rare case of solitary subcutaneous scalp metastasis from follicular thyroid carcinoma revealed with positron emission tomography/computed tomography: A case report and review. J Can Res Ther [serial online] 2014 [cited 2019 Sep 17];10:431-3. Available from: http://www.cancerjournal.net/text.asp?2014/10/2/431/136681
| > Introduction|| |
Follicular thyroid carcinoma (FTC) is the second most common type of thyroid cancer which is considered more aggressive than papillary carcinoma. Vascular invasion is characteristic for follicular carcinoma and therefore distant metastasis is more common. FTC can metastasize to lungs, bones, and brain via hematogenous spread.  Scalp is an uncommon site for metastasis and which is extremely rare.  Metastatic tumors to the scalp are most often from lung, breast, and prostate malignancies and rarely from thyroid cancers.  In this case, a 49-year-old patient with solitary scalp metastasis from follicular thyroid cancer was presented. The aim if this study was to discuss the imaging and therapy choice of scalp metastases of FTC and alsoto remind that follicular thyroid cancer can metastasize to the scalp.
| > Case Report|| |
A 49-year-old female patient admitted to hospital with bulging on the left vertex of the scalp. Patient had a subtotal thyroidectomy history 4-year ago and diagnosed with minimally invasive follicular thyroid cancer which was 0.9 cm in diameter. Radioactive iodine therapy was not given because of tumor size after the operation. Patient did not come to the hospital for follow-up examinations and blood test after this period. She was admitted to neurosurgery polyclinic because of bulging on the left side of vertex. She was referred to positron emission tomography (PET)/computed tomography (CT) examination for the evaluation of flourodeoxiglucose (FDG) uptake of this lesion to determine the biopsy side and also to search for the other possible metastases.
PET/CT whole-body imaging was performed after intravenous injection of 420 MBq (11.35 mCi) Flouro-18 FDG. After 1 h of waiting period in a silent room, the patient was imaged using an integrated PET/CT camera, which was consisted of a six-slice CT gantry, integrated with a lutetium oxyorthosilicate (LSO) based full-ring PET scanner (Siemens Bio-graph 6, IL, Chicago, USA). PET/CT images showed intense FDG uptake on the left vertex of the scalp with a soft-tissue component on CT slices with a maximum standard uptake value of (SUVmax) 9.8 [Figure 1]. Pathological FDG uptake was not seen on the thyroid bed, cervical regions, and on the skeletal system. After the PET/CT imaging, excisional biopsy was performed. Histopathological examination revealed a FTC metastasis [Figure 2]. After the operation, patient was referred to the nuclear medicine department for radioactive iodine therapy. High-dose I-131 was given and whole body I-131 imaging was performed 3 days after the therapy which showed focal uptake on thyroid bed [Figure 3]. Six months after the radioactive iodine therapy, low dose I-131 whole-body image was evaluated as normal and the patient's thyroglobulin levels were <0.05 ng/mL.
|Figure 1: Selected coronal, axial and sagittal positron emission tomography/ computed tomography and fusion images showed incresed flourodeoxiglucose uptake on the left vertex of scalp with SUVmax of 9.8|
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|Figure 2: H and E, ×200 magnification in exicisional biopsy slices showed thyroid follicular carcinoma forming follicles with uniform small nuclei|
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|Figure 3: Iodine I-131 whole body image revealed intense activity uptake in servical region releated with recurrent thyroid tissue. Focal uptake on the right shoulder is a marker|
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| > Discussion|| |
FTC is a subtype of thyroid cancer which is considered more aggressive than papillary carcinoma. Also, it has high propensity for bone and lung metastases. Vascular invasion is characteristic for follicular carcinoma and therefore distant metastasis is more common. Potential sites of distant spread include the lung, bone, brain, liver, bladder, and skin. FTC typically exhibits a slow progression and is associated with a favorable prognosis except when they present with metastasis. When distant metastasis occurs, it is associated with significant morbidity and mortality. Bone metastasis has long been recognized as the second most common form of metastases after lung metastasis in FTC.  Bone metastasis occurs more often in older patients and multiple-bone metastases are noted more often than a single-bone metastasis. 
Metastatic tumors to the scalp are usually observed in elderly patients and most often from lung, breast, prostate malignancies, and rarely from thyroid cancers.  In this case, the patient who was 49 years old, presented to the hospital with a bulging on the scalp after the operation. Scalp lesions are almost exclusively lytic, in a destructive character, and a soft tissue can be discovered.
The incidence of scalp metastasis of FTC is reported as 2.5-5.8%. In most reported cases, metastasis occurs after the diagnosis and treatment of primary tumor, but in a few cases, scalp metastasis was the first presentation of FTC.  Quinn et al. found scalp metastases in 9 of 14 patients with cutaneous metastases of FTC in a review.  Another case series of skull metastases from all types of thyroid cancers consists of 12 cases reported by Negamine et al. In this series, mean time from the diagnosis of thyroid tumor until discovery of skull metastasis was 23.3 years. 
In scalp metastasis of FTC, the best treatment options are the excision of the lesion, followed by thyroid tissue ablation with radioactive iodine I-131 and thyroid-stimulating hormone (TSH) suppression. 
As a result, it should be kept in mind that follicular thyroid cancer can rarely metastasize to the scalp. When evaluating scalp metastasis, PET/CT can be used to determine the biopsy site and other possible metastases of primary cancer. It is also essential to differentiate the histological subtypes of thyroid cancer for the treatment strategies and to determine prognosis when metastatic lesion is seen in the scalp.
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[Figure 1], [Figure 2], [Figure 3]