A 43-year-old Chinese male patient underwent ultrasonography at a local hospital because of swelling in the neck and face for 1 week. The patient complained of no pain in the neck and had no other symptoms except occasional respiratory disturbances. He was previously healthy and had no known medical conditions. There was no history of fever/cough, appetite loss, or weight loss. Ultrasound examination of the thyroid gland and bilateral cervical lymph nodes was performed at a local hospital, which suggested tuberculosis. The patient did not receive any medical treatment at the local hospital. Following this, the patient visited Hangzhou Red Cross Hospital for further examination. 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 striate hypoecho was observed in the middle and lower right lobe of the thyroid gland, suggesting thyroid invasion ( Figure 2 ). 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 ). We considered that the patient most likely had tuberculosis, either cervical vertebra tuberculosis or lymph node tuberculosis, considering that the mixed echoes of the neck reflected lymph node formation in a tuberculosis sinus tract. Thus, cervical spine computed tomography (CT) was performed immediately. However, the results showed no obvious abnormalities in the cervical cone or bone damage. A density of patchy fluid was observed on the posterior wall of the larynx (anterior cone of the cervical spine;  Figure 3B ). In the afternoon of the same day, we performed contrast-enhanced ultrasound (CEUS) evaluation, which revealed a large mixed-echo mass (areas III and IV) in the left neck, which rapidly filled with internal contrast agent and showed high enhancement at the peak. No nonenhancement areas were found. 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 ). Therefore, an ultrasound-guided puncture biopsy (with an 18-G core needle was performed ( Figure 4A ). The mixed-echo mass on the left side and one enlarged lymph node on the right side were punctured. Eight biopsy samples were collected from each site, and 2-cm long samples were sent for pathological examination, which suggested that the left neck mass was a quasi-circular malignant tumor with partial crush injury; thus, lymphoma was considered a possible diagnosis. The pathologic diagnosis of the right cervical lymph node sample was round-cell malignant tumor with focal coagulative necrosis ( Figure 4B ). Additional tests for tuberculosis, including acid-fast staining and the Xpert  test, were negative.
After excluding tuberculosis as a diagnosis, the patient was admitted to Zhejiang Cancer Hospital for specialized treatment. A relevant laboratory examination was completed after admission. The assessment of thyroid function revealed only an elevated level of antithyroid peroxidase antibodies (219.1 U/mL). Hypersensitive C-reactive protein level was 13.42 mg/L, which was slightly higher than the normal range. Since the disease onset, the patient exhibited a good clinical picture, with regular sleep pattern and no significant weight loss. In addition, the patient did not consume alcohol or tobacco products, had a harmonious family relationship, and did not have a familial genetic disease history. The patient has been living in Hangzhou, Zhejiang Province, China for a long time since birth and has no family history of tuberculosis; he was vaccinated against tuberculosis in accordance with the national regulations. CT before chemotherapy indicated the invasion of the superior vena cava (SVC). Furthermore, the patient's breathing was irregular. The patient underwent a second puncture biopsy using an 18-G core needle, and pathological analysis showed only the puncture result of one lymph node in the left neck. The tissue was fusiform, suggesting diffuse large B-cell lymphoma ( Figures 4C, D ).
Although the physical and additional clinical examinations suggested lymphadenopathy and potential lymphoma, the pathological classification was unclear. With the consent of the patient, surgical biopsy was performed, which led to the pathological diagnosis of PMBCL. At the last follow-up, the patient had completed the fifth cycle of chemotherapy (R-DA-EPOCH), with a favorable outcome. At present, he has no neck pain, nausea, fatigue, or other symptoms, and the swelling in the neck had resolved. Thyroid lesions had also improved. Informed consent was obtained for all invasive procedures performed in this case. The flowchart from disease discovery to diagnosis and treatment of the patient is shown in the  Figure 5 .