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Primary mediastinal thymoma combined with germ cell tumor (GCT) is extremely rare, and is likely to be misdiagnosed. Here we report a case of mediastinal type B3 thymoma combined with seminoma in which the seminoma component was missed by histologic examination and initially diagnosed by using a pleural effusion sample. The patient was a 46 year old male with chest distress, cough, and supraclavicular lymph node enlargement. A large anterior mediastinal mass was revealed by diagnostic imaging. The tumor was completely removed by thoracotomy. Grossly, a solid mass about 10 cm × 8 cm × 5 cm with cystic degeneration was found. Histologic examination revealed Type B3 thymoma accompanying with multiple lymph node metastases. One year later, CT scan found an irregular mass on the right side of anterior-superior mediastinum with a large amount of effusion in the right side pleural cavity. Cytologic examination and immunostains of the pleural effusion sample revealed metastatic seminoma. Then the original surgical sample was reviewed and the seminoma component also was found besides the thymoma. To the best of our knowledge, this is the first description of type B3 thymoma combined with seminoma, diagnosed by histology and pleural effusion together. We also present a literature review.

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BACKGROUND: It is a great challenge for pathologists to initially diagnose metastatic malignant mesothelioma (MM) by the lymph node biopsy without any history of primary MM. Because the onset of MM is hidden and the metastatic MM in lymph node is relatively uncommon. Besides, morphologic and immuohistochemistry features of MM are similar to other tumors. METHODS: In order to improve the initial diagnostic accuracy of metastatic MM from LN biopsy and to reduce or avoid the possibility of missed diagnosis or misdiagnosis, we had collected the clinical and pathological data of the metastatic MM cases in our department, and summarized the characteristics of morphological, immunohistochemical and fluorescence in situ hybridization (FISH) results. RESULTS: Seven patients (4 males and 3 females) with 21-73 year-old had been included in our study. Six cases showed serous cavity effusion, serosal thickening and systemic multiple lymph node enlargement. The "moderate, nice" tumor cells were arranged in variable patterns. Mitosis was hardly to be found and necrosis was absent. Four immunohistochemical staining panels and FISH detection had been used for diagnosis and differential diagnosis of MM. All cases expressed broad-spectrum epithelial markers and at least 2 mesothelial-cell-origin markers. None were positive for specific-tissue-origin markers, and all cases were diagnosed of malignancy according to immunohistochemical markers and detection of pl6 gene deletion. CONCLUSION: It is necessary for us to keep our awareness of metastatic MM in lymph node. Correct diagnosis of MM metastasis by lymph node biopsy were based on detailed understanding of the clinical manifestation and the image data, careful observation of morphologic characteristics, and properly using immunohistochemical markers or FISH detection if necessary for diagnosis and differential diagnosis.

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RATIONALE: Co-occurrence of medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC) in the same thyroid gland with liver metastasis is a rare condition. To our knowledge, the utility of contrast-enhanced ultrasound (CEUS) to diagnose it is much less. PATIENT CONCERNS: A 33-year-old female was referred to our hospital due to the increase in plasma calcitonin concentration and carcino-embryonic antigen 12 months after her total thyroidectomy. To find metastasis, she received laboratory tests, gray-scale US, and CEUS. In our paper, ethical approval was not necessary, as this article is a case report, which is based on the clinical information of the patient. Because our case does not refer to the patient's privacy, informed consent is not necessary. DIAGNOSES: Gray-scale abdominal ultrasound image demonstrated a mildly hyperechoic nodule in the liver. In CEUS, the nodules were hyperenhanced in the arterial phase. In the late arterial phase, the enhancement was washed out quickly. The nodules presented hypoenhancement in the portal and parenchymal phase, which conformed to the hepatic metastasis. INTERVENTIONS: The patient received thyroid and liver surgery. OUTCOMES: She was free of disease for 10 months at the time of this report. LESSONS: In this case, liver metastases from MTC can be detected and characterized reliably as hypoenhancing lesions during the portal venous and late phases of CEUS, washing out starts early, and is marked. We suspect MTC is a kind of tumor that tends to have rich blood supply and consider contrast-enhanced ultrasound as a suitable method for the follow-up of patients with MTC.

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BACKGROUND: The aim of this study was to assess the performance of apparent diffusion coefficient (ADC) measurement obtained with diffusion-weighted magnetic resonance imaging (DW-MRI) to distinguish renal cell carcinomas (RCCs) from small benign solid renal tumors (≤ 4 cm). METHODS: In this cross-sectional study, 49 consecutive patients with histopathologically confirmed small solid renal tumors, and seven healthy volunteers were imaged using nonenhanced MRI and DW-MRI. The ADC map was calculated using the b values of 0, 50, 400, and 600 s/mm 2 and values compared via the Kruskal-Wallis and Mann-Whitney tests. The utility of ADC for differentiating RCCs and benign lesions was assessed using a receiver operating characteristic curve. Multiple nonenhanced MRI features were analyzed by Logistic regression. RESULTS: The tumors consisted of 33 cases of clear-cell RCCs (ccRCCs) and 16 cases of benign tumors, including 14 cases of minimal fat angiomyolipomas and 2 cases of oncocytomas. The ADCs showed significant differences among benign tumors ([0.90 ± 0.52] × 10-3 mm 2 /s), ccRCCs ([1.53 ± 0.31] × 10-3 mm 2 /s) and the normal renal parenchyma ([2.22 ± 0.12] × 10-3 mm 2 /s) (P < 0.001). Moreover, there was statistically significant difference between high and low-grade ccRCCs (P = 0.004). Using a cut-off ADC of 1.36 × 10-3 mm 2 /s, DW-MRI resulted in an area under the curve (AUC), sensitivity, and specificity equal to 0.839, 75.8%, and 87.5%, respectively. Nonenhanced MRI alone and the combination of imaging methods led to an AUC, sensitivity and specificity equal to 0.919, 93.9%, and 81.2%, 0.998, 97%, and 100%, respectively. The Logistic regression showed that the location of the center of the tumor (inside the contour of the kidney) and appearance of stiff blood vessel were significantly helpful for diagnosing ccRCCs. CONCLUSIONS: DW-MRI has potential in distinguishing ccRCCs from benign lesions in human small solid renal tumors (≤ 4 cm), and in increasing the accuracy for diagnosing ccRCCs when combined with nonenhanced MRI.

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