Coexisting iodine avid and iodine nonconcentrating lesions with multiple distant soft tissue metastasis in papillary thyroid cancer

Findings of I-131 SPECT/CT, 18F-FDG, and 68Ga-FAPI-04 PET/CT Imaging in a Patient Treated with Radioiodine Therapy for Metastatic Papillary Thyroid Carcinoma

A 50-year-old man undergone total thyroidectomy and histopathology revealed papillary thyroid carcinoma with a tumor size of 4.5 cm. The patient was referred to a nuclear medicine clinic for radioiodine therapy. Since the thyroglobulin level before the treatment was 495 ug/L, low-dose (185 MBq) I-131 scan was performed. In addition to multiple liver metastases, bone metastases were detected in the sacrum and right 7^th rib in I-131 whole body scanning and single photon emission computed tomography/computed tomography (CT) imaging at the time of initial staging. We present a case of multiple metastatic papillary thyroid carcinoma whose radioiodine treatment response and clinical outcome were evaluated with ¹⁸F-fluorodeoxyglucose and Gallium-68 FAPI-04 positron emission tomography/CT.

Papillary thyroid carcinoma with hyperthyroidism and multiple metastases: A case report

RATIONALE

Papillary thyroid carcinoma (PTC) is the most common type of primary thyroid cancer with a low incidence of distant metastases. PTC represents more than 70% to -90% of thyroid malignancies. Distant metastases have only been observed in only 1% to 15% of patients with PTC. In this article, we reported the case of a patient with PTC and hyperthyroidism as well as simultaneous multiple metastases.

PATIENT CONCERNS

A 47-year-old man was admitted to our hospital on February 22, 2019, with several neck masses that had been present for 12 months, low back pain for 9 months, and lower limb paraplegia for 3 months.

DIAGNOSES

According to the patient physical examination, adjuvant examination (e.g., ultrasound, computed tomography, magnetic resonance imaging, blood test, and biopsy) and medical history, the clinical diagnosis was as follows: thyroid papillary carcinoma; cervical lymph node metastasis; multisite bone metastasis (6th and 7th cervical vertebrae, left clavicle proximal, right scapula bone, thoracic vertebrae, lumbar vertebrae, sacral vertebrae, bilateral ilium, and left pubic bone); muscular metastasis (the right medial femoral muscle, the vastus lateralis muscle, left thigh muscle, and the flexor superficialis of the left forearm); possible mediastinal lymph node metastasis; and paraplegia due to the soft-tissue metastasis around the 9th thoracic vertebral spine; and hyperthyroidism (free thyroxine: 36.59 pmol/L, free triiodothyronine: 9.58 pmol/L, thyroid-stimulating hormone: 0.005 μIU/mL, thyroid autoantibody: 2.53 IU/L).

INTERVENTIONS AND OUTCOMES

The patient refused to undergo further intervention or follow-up.

LESSONS

In summary, this is the 1st case of in which a patient with PTC and hyperthyroidism, as well as simultaneous multiple skeletal muscles and bone metastases, lymph node metastasis, and paraplegia was observed. In practice, in cases where patients have PTC and hyperthyroidism, practitioners should perform further examinations to rule out the presence of distant metastases. We believe that the use of ultrasound has a unique advantage in the diagnosis of PTC and skeletal muscle metastasis.

Skeletal Muscle Metastasis in Papillary Thyroid Microcarcinoma Evaluated by F18-FDG PET/CT

Papillary thyroid cancer (PTC) is the most common type of thyroid malignancy and is characterized by slow growth and an indolent biological behavior. Papillary thyroid microcarcinoma is the PTC with the maximum size of the tumor <1cm, considered the most indolent form of thyroid cancer. PTC is usually metastasizes in cervical lymph nodes, lungs and bones and, less commonly, in brain or liver. Skeletal muscle metastases from PTC are extremely rare, a retrospective review of the literature revealed only 13 case reports. Among them, six cases are solitary skeletal muscle metastases, and seven are multiple metastases, most of them being associated with lung lesions. It seems that PTC is prone to metastasizing to the erector spinae and thigh muscles groups with unique cases located in trapezoid, biceps, deltoid, gastrocnemius and rectus abdominis muscles. Although extremely rare, one must bear in mind the fact that muscle metastasis from PTC is possible, and that is the reason we would like to discuss the existing clinical cases and to add a unique case of solitary skeletal muscle metastasis from papillary microcarcinoma.

Skeletal muscle metastases from papillary and follicular thyroid carcinomas: An extensive review of the literature

Skeletal muscle metastasis of papillary or follicular thyroid cancer (PTC/FTC) is a rare finding; only 11 cases of skeletal muscle PTC or FTC metastasis have been included in medical literature reviews. The aim of this study was to identify all published cases of PTC and FTC muscle metastases and derive the true incidence of this malignancy. The probability of detecting the skeletal muscle metastasis of PTC and FTC was calculated based on epidemiological data. Databases of scientific literature on the Internet were searched for articles using relevant key words. The analysis of epidemiological data calculated the probability of detecting skeletal muscle lesions of this type as approximately zero. The literature search revealed 44 published international papers, reporting 58 cases of PTC or FTC skeletal muscle metastasis in 45 patients over 110 years, from 1907 to 2017. The most frequent PTC/FTC metastatic muscle was the gluteus. The majority of cases of muscle metastasis were caused by PTC, and metastatic tumors in the skeletal muscle negatively impacted the survival of patients with PTC or FTC.