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case_images: Lymphadenopathy noted on ultrasound in the neck of a 43-year-old male patient diagnosed with primary mediastinal B-cell lymphoma. (A) Sonogram revealing enlarged lymph nodes of the right neck, 3.0 x 1.6 cm in size, oval, uneven, and with a fair margin. (B) Color Doppler examination showing abundant blood flow in enlarged lymph nodes of the right neck, a lymphatic hilum, PSV: 21.0 cm/s, RI: 0.64. (C) Contrast-enhanced ultrasound showing abundant lymph node blood supply in area III of the right neck. (D) Shear-wave elastography of the lymph node, which is indicated by the mostly blue area. PSV, peak systolic velocity; RI, resistance index.
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case_images: During the examination, multiple enlarged lymph nodes with clear margins and uneven internal echoes were found in the neck; lymphatic hilum blood flow could be noted; and the lymph nodes appeared mostly blue on ultrasound shear-wave elastography, indicating a firm texture ( Figure 1 ). A cervical lymph node in area III, which was 3.0 x 1.6 cm in size, suggested a rich blood supply and exhibited centripetal and high enhancements at the peak ( Figure 1 ).
case_images: Transverse and longitudinal ultrasound showing thyroid invasion. (A) Ultrasound transects of thyroid showing a hypoechoic, irregular, and ill-defined thyroid at the right side. (B) Ultrasonography of the thyroid showing a low-echo area in the middle and lower part of the right thyroid gland, with an uneven internal echo, irregular shape, and unclear boundary. (C) Shear-wave elastography showing the hypothyroid area on the right as the essentially blue area. (D) Color Doppler ultrasonography showing minimal blood flow signal in the hypoechoic thyroid area.
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case_images: A striate hypoecho was observed in the middle and lower right lobe of the thyroid gland, suggesting thyroid invasion ( Figure 2 ).
case_images: Ultrasound and computed tomography showing the posterior neck. (A) Ultrasound showing mixed echoes on the left side of the neck, poorly demarcated from the surrounding soft tissue and appearing to extend deep into the neck. This presentation is similar to the formation of tuberculous sinus passages in lymph nodes. (B) Neck computed tomography showing streaky fluid density shadows in front of the cone (yellow arrow points).
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case_images: Simultaneously, a mixed-echo mass indistinguishable from the surrounding soft tissue was found upon imaging of the left neck, which resembled the formation of a sinus following the rupture of lymph node tuberculosis; abnormal echoes were also present in front of the cervical spine ( Figure 3A ). A density of patchy fluid was observed on the posterior wall of the larynx (anterior cone of the cervical spine;  Figure 3B ).
case_images: Puncture specimen obtained through ultrasound-guided puncture and histopathologic images showing cells with pleomorphism. (A) Puncture specimen of the right cervical lymph node (obtained from the Hangzhou Red Cross Hospital). (B) Pathological images taken with an optical microscope at 400x magnification (right cervical lymph node, obtained from the Department of Pathology at Hangzhou Red Cross Hospital). (C) Pathological images taken with an optical microscope at 10x magnification (left cervical lymph node, obtained from the Department of Pathology at Zhejiang Cancer Hospital). (D) Pathological images taken at 40x magnification under an optical microscope (left cervical lymph node, obtained from the Department of Pathology at Zhejiang Cancer Hospital).
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case_images: Therefore, an ultrasound-guided puncture biopsy (with an 18-G core needle was performed ( Figure 4A ). The pathologic diagnosis of the right cervical lymph node sample was round-cell malignant tumor with focal coagulative necrosis ( Figure 4B ). The tissue was fusiform, suggesting diffuse large B-cell lymphoma ( Figures 4C, D ).
case_images: The flowchart from disease discovery to diagnosis and treatment of the patient.
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case_images: The flowchart from disease discovery to diagnosis and treatment of the patient is shown in the  Figure 5 .