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Background Thymomas generally arise from the thymus in the anterior mediastinum. Ectopic thymomas arising in the middle mediastinum are rare. We present a case of a thymoma arising from the ectopic thymic tissue in the right paratracheal region. Case presentation The patient was a 67-year-old male who underwent an enhanced-computed tomography examination as preoperative staging for colon cancer. A 20-mm nodule in the right paratracheal region was found incidentally. Fluorodeoxyglucose (FDG) accumulation was detected in this solitary nodule by FDG-positron emission tomography, mimicking an enlarged, possibly malignant lymph node. The tumor was removed by thoracoscopic surgery, and a postoperative pathological diagnosis of type AB thymoma was made. Foci of ectopic thymic tissues were found adjacent to the thymoma. The patient was disease-free and without recurrence 2 years postoperatively. Conclusions Including the present case, 13 cases of ectopic paratracheal thymoma have been reported in the English literature, all of which were found on the right side of the paratracheal region. Although ectopic thymomas in the paratracheal region are rare, thymomas may be considered as a differential diagnosis for a paratracheal nodule.

Thymoma is an epithelial neoplasm of the thymus, which commonly lies in the anterior mediastinum and, therefore, an intrathoracic origin is considered to be rare. This report presents a case of giant thymoma arising in the thoracic cavity. A 61-year-old male presented with a chronic cough and breathlessness. Chest CT revealed a well enhanced giant mass approximately 18 cm in diameter in the right thoracic cavity. FDG-PET showed that the SUVmax of the tumor was 5.0 in the center and almost 2.5 in the surrounding area. A trans- bronchial needle biopsy was performed to find atypical cells. Surgery was scheduled based on the radiological and histological findings. A well-defined giant mass in the thoracic cavity, measuring 18 × 14.5 × 11 cm had undergone expansive growth without apparent invasion. The tumor was completely resected without combined resection of the other organs. The weight of the tumor was 1350 g. The tumor was histologically diagnosed to be type AB thymoma according to the World Health Organization classification and Masaoka stage IIB.

Two cases of thymomas with pure red cell aplasia (PRCA) are presented, highlighting variability in their anatomic location, ambiguity in presentation, indolence of course and unpredictability of response to treatment. Multi-modality approach is necessary for both diagnosis and management of this combination. Duration and side effects of treatment determine the overall prognosis.

Ectopic cervical thymomas are often confused with thyroid or parathyroid swellings due to their anatomical positioning. Predominant epithelial thymoma can be misdiagnosed as papillary thyroid carcinoma on fine needle aspiration and lymph node metastasis of epithelial tumor on frozen section. Predominantly lymphocytic thymomas have often been misinterpreted as Hashimoto′s thyroiditis or malignant lymphoma, either by fine needle aspiration or on frozen section analysis. If cytology is doubtful and is not correlating with clinical, anatomical and surgical findings; immunohistochemistry is a very important tool in such cases to give final answer. Thyroid cell specific proteins such as thyroglobulin, thyroid transcription factor-1, thyroperoxidase and dipeptidyl aminopeptidase-4, neuroendocrine markers chromogranin, calcitonin and parathyroid hormone could be used to rule out thyroid or parathyroid origin. We present such rare case of ectopic cervical thymoma mimicking as papillary thyroid carcinoma.

We present a case of a 53 year old man with a thymoma near the pericardium, a rare ectopic localisation of thymoma. A round radiodensity found at the right cardiophrenic angle was initially suspected at the echocardiography to be a pericardial cyst. The diagnosis of thymoma was made only after histopathological examination of the surgically re-sected lesion.