INTRODUCTION: Thymic Carcinoids (TC) are rare tumors of the mediastinum with fewer than 200 reported cases in the literature. These tumors are frequently associated with endocrinopathies and carry a poor prognosis. TCs behave aggressively in contrast to that of generally benign carcinoids that arise elsewhere in the body. Most TCs present as anterior mediastinal masses. We report a case of a metastatic carcinoid presenting as a posterior mediastinal mass.
CASE PRESENTATION: A 65-year-old asymptomatic male was found to have an abnormal chest x-ray after suffering a fracture of his right forearm. The x-ray showed evidence of a large paratracheal mass with tracheal deviation. His workup included a CT scan of the chest showing a large 5 x 5.5 x 3.8 cm right paratracheal mass with a 1.3 cm hypodensity in the adrenal gland. Fiberopticbronchoscopy with transbronchial needle aspiration was performed. Cells obtained formed cords, nests, and rosettes. The cells stained strongly for cytokeratins AE1/AE3, synaptophysin, CD 15, EMA, and vimentin. The stains were negative for NSE, CK 7, CK20, and CD 45. This staining pattern in association with morphology is consistent with a carcinoid tumor. A bone scan showed multiple areas of abnormal uptake in the proximal right radius and distal right humerus, proximal left humerus, right wrist, and right greater trochanter.
DISCUSSIONS: Carcinoid (“Karzinoide”) tumors, as first described by Oberndorfer in 1907, are rare neuroendocrine tumors with an incidence of only 1.5 cases per 100,000 of the general population. Pulmonary or bronchial carcinoid tumors account for over 20% of all carcinoid tumors and for 1%–2% of all pulmonary neoplasms. Primary thymic carcinoid is exceedingly rare. They were first described by Rosai and Higa in 1972. They arises from normal thymic Kulchitsky's cells and account for approximately 2% to 4% of all mediastinal neoplasms and 5% of thymic tumors. TCs are classified into grade 1 (typical), grade 2 (atypical), and grade 3 (large-cell and small-cell carcinoma). The behavior of carcinoid in the thymus differs from that of carcinoid in the lung. Thymic carcinoids are malignant neuroendocrine neoplasms with the potential for aggressive local, regional, and distant spread. They are frequently associated with endocrinopathies with 33% to 40% of thymic carcinoids producing ACTH resulting in Cushing's syndrome. 25% of patients with thymic carcinoid have the syndrome of multiple endocrine neoplasia type 1 (MEN-1).Surgery offers the best hope for treatment. Complete resection may not always be possible as patients frequently have metastases at the time of presentation. Partial resections has a high recurrence rate. In a series published by Best and colleagues , only 9 out of 16 patients were able to undergo complete resection. However, local or distant metastasis developed in all patients. Radiotherapy and chemotherapy have not been proven to improve survival. One case report mentions successful treatment with a somatostatin analogue (Octreotide) in conjunction with chemotherapy and radiotherapy.
CONCLUSION: Thymic carcinoid tumors are rare, aggressive neuroendocrine tumors which usually present as an anterior mediastinal mass. Our patient is unusual in that he presented with a posterior mediastinal mass. Extension or ectopic thymus has been described in the literature. We suspect that in our patient the carcinoid occurred in an ectopic thymus in the posterior mediastinum. As in most cases, our patient presented with metastases at the time of diagnosis ruling out surgical resection. Chemotherapy, radiotherapy, and the addition of octreotide therapy were initiated in this case.
DISCLOSURE: Tarik Haddad, None.