Abstract
A 56-year-old male patient underwent total thyroidectomy, and pathology revealed multicentric papillary thyroid cancer. His post-operative stimulated thyroglobulin value was >500 ng/mL. 18F-fluorodeoxyglucose positron emission tomography (PET) computed tomography revealed hypermetabolic metastatic pulmonary nodules, cervical, and mediastinal lymph nodes. There was also a hypermetabolic lesion in the left gluteal muscle. Due to the patient’s history of a pilonidal cyst in the same region, the possibility of an abscess was also considered, and due to the absence of radioactive iodine (RAI) uptake in the lesion, follow-up was deemed appropriate. During follow-up, as the patient progressed to RAI-refractory state, 68Ga-DOTATATE PET/magnetic resonance imaging, which was done for radionuclide therapy planning, revealed heterogeneously increased uptake in the gluteal lesion. A subsequent biopsy confirmed the diagnosis of PTC metastasis.
Keywords: PET/MRI, FDG; 68Ga DOTATATE; thyroid cancer; muscle; metastasis
Öz
Elli altı yaşında erkek hasta total tiroidektomi sonucunda multifokal papiller tiroid kanseri (PTK) tanısı almıştır. Postoperatif stimüle tiroglobulin değeri >500 ng/mL olarak ölçülmüş olup yapılan 18F-florodeoksiglukoz pozitron emisyon tomografisi (PET) bilgisayarlı tomografi hipermetabolik metastatik pulmoner nodüller, servikal ve mediastinal lenf nodları saptanmıştır. Ayrıca sol gluteal bölgede kastahipermetabolik bir lezyon saptanmıştır. Aynı bölgede pilonidal kist öyküsü de olan hastada abse ihtimali de değerlendirilmiş olup lezyonda radyoaktif iyot (RAİ) tutulumu da olmaması üzerine takip uygun görülmüştür. RAİ refrakter duruma geçen hastaya yapılan 68Ga-DOTATATE-PET/manyetik rezonans görüntülemesinde gluteal lezyonda heterojen artmış aktivite tutulumu gözlenmesiyle birlikte yapılan biyopsi PTK metastazı tanısını doğrulamıştır.
Keywords: PET/MRI, FDG, 68Ga DOTATATE, tiroit kanseri, kas, metastaz
Ethics
Informed Consent: Informed consent was obtained from the patient for the use of their imaging data.
Figure 1.
18F-fluorodeoxyglucose-positron emission tomography (18F-FDG PET) is beneficial in high-risk thyroid cancer patients who have increased thyroglobulin (Tg) levels (>10 ng/mL) for both metastasis detection and prognostication (1,2,3). 68Ga-DOTATATE PET can also be performed for metastasis detection and for 177Lu DOTATATE treatment planning (4,5,6). While cervical lymph nodes, lungs, and bones are the most common sites of metastasis, papillary thyroid carcinoma (PTC) can also metastasize to the brain, kidneys, liver, and adrenal glands (7). Skeletal muscle metastases are extremely rare (8). Our patient had a bilateral total thyroidectomy operation, and the pathology result revealed multicentric (R: 1.1, 0.3, 0.2 cm; L: 7 cm) PTC (follicular, oncocytic follicular, classical variants, and diffuse sclerosing variant containing tall cell areas) and 1/1 central lymph node metastasis. His post-operative stimulated Tg value was >500 ng/dL, and 18F-FDG PET/computed tomography was performed to detect metastasis, which revealed cervical and mediastinal lymph nodes, and pulmonary metastases. Moreover, a 75x36x44 mm hypermetabolic lesion was detected inside the left gluteal muscle [maximum standardized uptake value (SUVmax)=40.08]. After receiving a total of 750 mCi of radioactive iodine (RAI) therapy, the patient was considered RAI-refractory because of sustained high serum Tg levels. The gluteal lesion did not show radioiodine uptake. The patient underwent 68Ga-DOTATATE PET for radionuclide therapy planning due to a state refractory to RAI. The gluteal lesion showed increased DOTATATE uptake (73x38x40 mm, SUVmax=10.43), which increased suspicion for the lesion. A biopsy was performed to rule out a second primary malignancy, and it confirmed thyroid cancer metastasis. Besides being extremely rare, this is the first report of a 68Ga-DOTATATE PET/magnetic resonance imaging (MRI) of thyroid cancer muscle metastasis, to our knowledge. 18F-FDG PET (A),computed tomography (B), and maximum intensity projection (MIP) (C) images of the patient showed a well-circumscribed left gluteal lesion, which had an intense FDG uptake (red arrows). 68Ga-DOTATATE PET (D), T1-weighted MRI (E), and MIP (F) images showed heterogeneously increased 68Ga-DOTATATE uptake (blue arrows).
Figure 2.
Biopsy histological image. Papillary thyroid carcinoma within skeletal muscle and collagenous tissue [H&E, x40 (G) and x400 (H) magnification], skeletal muscle tissue (blue arrow), collagenous fibrous tissue (yellow arrow), thyroid cancer cells (red arrows).
Figure 3.
Post-RAI MIP images: the first 250 mCi image (I) shows thyroid bed and mediastinal lymph node uptake (black arrows). The second 250 mCi image (J) shows a lymph node uptake (black arrow). The third 250 mCi image (K) shows a more faint lymph node uptake (black arrow). The gluteal lesion did not show uptake.
RAI: Radioactive iodine, MIP: Maximum intensity projection
Footnotes
Authorship Contributions: Surgical and Medical Practices: A.K., Concept: A.K., S.A., L-U.B., M.Ö., S.S., K.S., H.B.S., Design: A.K., S.A., Data Collection or Processing: A.K., S.A., L-U.B., M.Ö., S.S., K.S., H.B.S., Analysis or Interpretation: A.K., S.A., L-U.B., M.Ö., S.S., K.S., H.B. S., Literature Search: A.K., Writing: A.K.
Conflict of Interest: No conflicts of interest were declared by the authors.
Financial Disclosure: The authors declare that this study has received no financial support.
References
- 1.Haugen BR, Alexander EK, Bible KC, Doherty GM, Mandel SJ, Nikiforov YE, Pacini F, Randolph GW, Sawka AM, Schlumberger M, Schuff KG, Sherman SI, Sosa JA, Steward DL, Tuttle RM, Wartofsky L. 2015 American thyroid association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer: the American Thyroid Association Guidelines task force on thyroid nodules and differentiated thyroid cancer. Thyroid. 2016;26(1):1–133. doi: 10.1089/thy.2015.0020. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Haslerud T, Brauckhoff K, Reisæter L, Küfner Lein R, Heinecke A, Varhaug JE, Biermann M. F18-FDG-PET for recurrent differentiated thyroid cancer: a systematic meta-analysis. Acta Radiol. 2016;57(10):1193–1200. doi: 10.1177/0284185115594645. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Manohar PM, Beesley LJ, Bellile EL, Worden FP, Avram AM. Prognostic value of FDG-PET/CT metabolic parameters in metastatic radioiodine-refractory differentiated thyroid cancer. Clin Nucl Med. 2018;43(9):641–647. doi: 10.1097/RLU.0000000000002193. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Roll W, Riemann B, Schäfers M, Stegger L, Vrachimis A. 177Lu-DOTATATE Therapy in radioiodine-refractory differentiated thyroid cancer: a single center experience. Clin Nucl Med. 2018;43(10):e346–e351. doi: 10.1097/RLU.0000000000002219. [DOI] [PubMed] [Google Scholar]
- 5.Vrachimis A, Stegger L, Wenning C, Noto B, Burg MC, Konnert JR, Allkemper T, Heindel W, Riemann B, Schäfers M, Weckesser M. [(68)Ga]DOTATATE PET/MRI and [(18)F]FDG PET/CT are complementary and superior to diffusion-weighted MR imaging for radioactive-iodine-refractory differentiated thyroid cancer. Eur J Nucl Med Mol Imaging. 2016;43(10):1765–1772. doi: 10.1007/s00259-016-3378-5. [DOI] [PubMed] [Google Scholar]
- 6.Versari A, Sollini M, Frasoldati A, Fraternali A, Filice A, Froio A, Asti M, Fioroni F, Cremonini N, Putzer D, Erba PA. Differentiated thyroid cancer: a new perspective with radiolabeled somatostatin analogues for imaging and treatment of patients. Thyroid. 2014;24(4):715–726. doi: 10.1089/thy.2013.0225. [DOI] [PubMed] [Google Scholar]
- 7.UpToDate. https://www.uptodate.com/contents/papillary-thyroid-cancer-clinical-features-and-prognosis (2025, accessed February 2025)
- 8.Herbowski L. Skeletal muscle metastases from papillary and follicular thyroid carcinomas: An extensive review of the literature. Oncol Lett. 2018;15(5):7083–7089. doi: 10.3892/ol.2018.8216. [DOI] [PMC free article] [PubMed] [Google Scholar]