Thyroid in the Thigh A Rare Presentation of Follicular Carcinoma
Mourouguessine Vimal, Professor, Department of Pathology, Sri Manakula Vinayagar Medical College and Hospital, Pondicherry,
Neha Sikdar, Senior Resident, Department of Pathology, Andaman and Nicobar Islands Institute of Medical Sciences.
Address for Correspondence
Dr. Mourouguessine Vimal,
Department of Pathology,
Sri Manakula Vinayagar Medical College and Hospital,
Kalitheerthalkuppam, Puducherry 605107, India.
Vimal M, Sikdar N. Thyroid in the Thigh A Rare Presentation of Follicular Carcinoma. Online J Health Allied Scs.
2021;20(2):9. Available at URL:
Submitted: May 21,
2021; Accepted: July 30, 2021; Published: Aug 25, 2021
Thyroid carcinoma is the commonest endocrine malignancy. The incidence is as high as 23,500 and 19,000 new cases per year in the United States and the European Union, respectively. Thyroid tumors can be divided based upon tumors exhibiting follicular cell differentiation or C-cell differentiation or both.
Follicular thyroid carcinoma is the follicular cell derived thyroid neoplasm and is the second most common thyroid cancer after papillary carcinoma. It is mostly seen in patients over 40 years of age with female predominance and accounts for 1020% of all thyroid malignancies. It typically presents as an asymptomatic solitary thyroid nodule. These neoplasms tend to metastasize hematogenously, most commonly to the lungs and bones. However, metastasis to the skeletal muscles is extremely rare.[3-4]
Fine needle aspiration (FNA) remains the gold standard for evaluating a thyroid nodule. It is highly sensitive and plays a major role as a screening test for follicular carcinomas. Current guidelines from the National Comprehensive Cancer Network (NCCN) recommend that patients with thyroid nodules undergo measurement of thyroid-stimulating hormone (TSH) and ultrasound of the thyroid and central neck. Computed Tomography (CT) can be done to assess its extent and metastasis. Surgery is found to be the most optimum treatment with most of the patients responding well to total thyroidectomy, radioiodine-131 ablation and levothyroxine suppression treatment. The prognosis usually depends upon the prognostic factors and is mostly poor with median survival from 626 months.
To the best of our knowledge, we believe that there have been only few cases of follicular thyroid carcinoma with soft tissue metastasis reported in the literature.
A 55 year old female came with the complaint of swelling over the neck since 30 years and a swelling over right side groin since 15 days. The patient gave history of trauma few days back. No other relevant complaints were noted. Local examination revealed a swelling of size 25x20cm noted in the anterior part of neck and another swelling of size 8x6cm noted over right medial aspect of thigh.
Ultrasonography (USG) of neck showed a very large mass seen in the right side of neck measuring 30x25cm which appears predominantly hyperechoic with multiple cystic components suggestive of necrosis. Impression was given as neurofibroma. USG of right thigh showed an ill-defined, heterogenous, predominantly hyperechoic collection measuring 7.9x7.7x7.5cm noted in the medial aspect of thigh with increased vascularity. Impression was given as hematoma.
Ultrasound guided fine needle aspiration was done. The smears from thyroid were highly cellular and showed numerous medium sized follicles, papillaroid clusters of follicular cells with mild nuclear anisokaryosis and moderate amount of cytoplasm. Many of the follicular cells exhibited Hurthle cell changes and few follicles showed scanty colloid. Background showed scattered naked nuclei (Figure.1). The smears from the right thigh swelling also showed similar cytological features (Figure. 2). Thus a diagnosis of follicular neoplasm with thigh metastasis was made.
Patient was not willing for surgery following which she was discharged on request. She was lost to follow up.
Figure 1. Photograph shows patient with huge neck swelling and FNA from the swelling showing repetitive clusters of thyroid follicular cells (MGG;x100).
Figure 2. Photograph shows swelling over medial aspect of right thigh and FNA from the swelling showing follicular cell clusters (MGG; x400).
Follicular carcinoma is the second most prevalent malignancy of the thyroid after papillary thyroid carcinoma representing approximately 15% of all thyroid carcinomas. They can be minimally invasive or widely invasive. Mostly they are minimally invasive and are categorized as well differentiated tumors that have an excellent prognosis. Some are widely invasive carcinomas with a much more aggressive clinical course.
Peak onset of follicular thyroid cancer is between 40-60 years with female preponderance. Female to male ratio is 3:1. It is rarely associated with radiation exposure. Hematogenous spread is common to lung, bone and other solid organs. Only less than 10% of follicular carcinoma presents with the evidence of lymphatic involvement. Invasion into vascular structures within the thyroid gland is common. Metastasis can also be seen to kidney and skin. The skeletal metastases are usually multicentric but have a predilection for the shoulder girdle, sternum, skull and iliac bone. However, metastasis to the skeletal muscles is extremely rare. The most frequent metastatic muscles, as reported in the literature are the gluteus, sternocleidomastoid and thigh. The incidence of distant metastasis in follicular cancer has been reported as 620%.
Follicular carcinomas that are well circumscribed isolated and minimally invasive may be treated with hemi-thyroidectomy and isthmusectomy. Widely invasive lesions should be treated with total thyroidectomy and radioactive iodine-131 ablation. The prognosis of follicular carcinoma largely depends upon few prognostic factors. The commonly used prognostic factors include age over 45 years, size of tumor greater than 4cm, presence of extra thyroidal extension and distant metastasis.
A high serum thyroglobulin level that had previously been low following total thyroidectomy, especially if gradually increased with thyroid stimulating hormone (TSH) stimulation, is indicative of recurrence. Levels greater than 10 ng/ml is often associated with recurrence even if an iodine scan is negative. Patients with differentiated thyroid carcinoma have a 10-year survival rate of 8095%. However, when distant metastases are present, the overall 10-year survival rate is only 40%.
This case of follicular thyroid carcinoma with soft tissue metastasis is reported for its clinical rarity and also to highlight the utility of Fine needle aspiration as a screening tool for the diagnosis of follicular lesions of thyroid. However, surgical excision is required in all these cases for histopathological examination for further management of the patient.
- Tunio MA, Alasiri M, Riaz K, Alshakwer W, Alarifi M. Skeletal Muscle Metastasis as an Initial Presentation of Follicular Thyroid Carcinoma: A Case Report and a Review of the Literature. Case Rep Endocrinol. 2013;2013:192573.
- Rosai J. Rosai and Ackermans surgical Pathology. 10th ed. Elsevier; 2011: p. 505-22.
- Panda KS, Patro B, Samantaroy MR, Mishra J, Mohapatra KC, Meher RK. Unusual presentation of follicular carcinoma thyroid with special emphasis on their management. Int J Surg Case Rep 2014;5(7):40811.
- Olejarski J, Yang M, Varghese J. Follicular thyroid carcinoma presenting as a soft tissue thigh mass. Lancet Diabetes Endocrinol 2014;2(4):348.
- Clark DP, Faquin WC. Thyroid Cytopathology. Springer; 2005: p. 64-87.
- Schneider DF, Chen H. New developments in the diagnosis and treatment of thyroid cancer. CA Cancer J Clin. 2013;63(6):374-94.
- Herbowski L. Skeletal muscle metastases from papillary and follicular thyroid carcinomas: An extensive review of the literature. Oncol Lett 2018;15(5):70839.
- Parameswaran R, Hu JS, En NM, Tan WB, Yuan NK. Patterns of metastasis in follicular thyroid carcinoma and the difference between early and delayed presentation. Ann R Coll Surg Engl 2017;99(2):1514.
- Gray W, Kocjan G. Diagnostic Cytopathology. 3rd ed. Elsevier; 2010: p. 498-99.
- Indrasena BSH. Use of thyroglobulin as a tumour marker. World J Biol Chem 2017;8(1):815.