PMC7188785_01
Images of patient and subcutaneous nodules. (A) Multiple subcutaneous soft tissue nodules of metastatic follicular thyroid carcinoma on the anterior neck. (B) Gray-scale ultrasound shows a hypoechoic nodule in the subcutaneous soft tissue of left neck (size were 16 x 11 mm), with wider than taller, well-defined border, irregular margin, perinodular, and intranodular flow and absence of calcification and peripheral halo. (C) Gray-scale ultrasound shows two solid hypoechoic nodules adjacent to each other in the subcutaneous soft tissue of right neck (size of the larger one were 28 x 23 mm), with wider than taller, partially well-defined border, partially regular margin, perinodular and intranodular flow and absence of calcification and peripheral halo. (D) Computed tomography shows several low-density nodules in the subcutaneous of the anterior neck. (E)
99mTcO4-SPECT reveals a shadow of a cold nodule in the right anterior neck region and a shadow of a nodule in the left anterior neck region.
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F1
In May 2019, the patient revisited our hospital with multiple asymptomatic, soft, protruding nodules on the anterior neck (Figure 1A). Neck US revealed several solid nodules with the similar US features in the left anterior neck, the larger one displayed a well-defined border and irregular margin (Figure 1B). In the right anterior neck, two solid nodules adjacent to each other with a partially well-defined border and partial regular margin (Figure 1C) were found. All of them showed solid hypoechogenicity, wider than tall, no calcification, absent peripheral halo and perinodular and intranodular flow, while CT revealed multiple low-density nodules in the subcutaneous tissue of the bilateral anterior neck (Figure 1D). SPECT found a shadow of a cold nodule in the right anterior neck region and a shadow of a nodule in the left anterior neck region (Figure 1E).
Contrast-enhanced ultrasound and elastosonography appearance of the larger subcutaneous nodules on the bilateral neck. (A,B) Contrast-enhanced ultrasound showed both the larger nodule in the bilateral neck are hypervascular, heterogeneous enhancement, no ring enhancement, and partially clear enhanced boundary. (C,D) Elastosonography displayed both the larger one were mainly composed of blue color (at least 75% of the nodule was covered in blue). (E)
99mTcO4-SPECT whole body scan was performed and showed no abnormal uptake in the whole body.
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F2
Furthermore, the contrast-enhanced ultrasound showed hyper-vascular, larger nodules of bilateral neck with heterogeneous enhancement, no ring enhancement and partially clear enhanced boundary (Figures 2A,B). Elastosonography displayed both larger nodules mainly composed of blue color (at least 75% of the nodule was covered in blue) (Figures 2C,D). As the patient refused 131I whole body scan and 18-fluorodeoxyglucose positron-emission tomography/CT (18F-FDG-PET/CT) scan, 99mTcO4-SPECT whole body scan was performed, showing no abnormal uptake in the whole body (Figure 2E).
Follicular thyroid carcinoma. (Hematoxylin and eosin staining of histological slides, x 200).
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F3
Under the microscope, the tumor cells were arranged in the form of small follicles, with acidophilic cytoplasm, enlarged, hyperchromatic nuclei and vascular invasion (Figure 3).
The TERT promoter testing displayed a mutation type (position g 1,295, 228 C>T). Genomic DNA was isolated from four 5 mum-thick slices of formalin-fixed paraffin-embedded metastatic follicular thyroid carcinoma samples, using a commercial DNA extraction kit (TIANamp FFPE DNA Kit, TIANGEN, Catalog No. DP130608, China), according to the instruction of the manufacturer. The TERT promoter region (2 mutation hot spots:chr5:1,295, 228 C>T and chr5:1,295, 250 C>T) was amplified with a commercial kit (TERT Genetic Mutation Detection Kit, SinoMD, Catalog No. 20090031, China), according to the manufacturer's instructions. The amplified products were sequenced with Applied Biosystems 3,500 Genetic Analyzeror and mutations were recognized on sequencing electropherograms.
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F4
TNM staging of this patient was T4aN0bM0. The TERT promoter mutation testing was positive (position g 1,295, 228 C>T) (Figure 4).