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

Abstract

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.

Prognostic Role of 2-[18F]FDG PET/CT Metabolic Volume Parameters in Patients Affected by Differentiated Thyroid Carcinoma with High Thyroglobulin Level, Negative 131I WBS and Positive 2-[18F]-FDG PET/CT

“…Bone and lungs were the most frequent sites of distant metastases in DTC, but rarer localizations are also possible [29,30] A further potential help in the study of this kind of patients could derive from the introduction of PET/MRI instead of PET/CT.…”

“…Bone and lungs were the most frequent sites of distant metastases in DTC, but rarer localizations are also possible [ 29 , 30 ]…”

TTN mutations predict a poor prognosis in patients with thyroid cancer

“…The follicular-derived thyroid cancers are divided into well-differentiated papillary thyroid cancer (PTC), follicular thyroid cancer (FTC), poorly differentiated thyroid cancer (PDTC), and anaplastic thyroid cancer (ATC). PTC is one of the most common forms of THCA [ 3 ]. Although well-differentiated thyroid cancers, such as PTC, have a good prognosis, the mortality rates of PDTC and ATC are still relatively high [ 4 ].…”

Solitary Nasopharyngeal Metastasis From Papillary Thyroid Carcinoma Shown on FDG PET/CT

“…[2][3][4][5] The most common site of metastasis is local lymph nodes followed by the lung and the bones. However, it can also rarely metastases to the other organs, including the adrenal, 6 skeletal muscle, 7 both female 8 or male 9 breast, pancreas, 10 brain, 11 kidney, 7,12 liver, 13 and the skin. 14 Our case is special for 2 reasons.…”