대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Thymic Carcinoid Tumor

Radiologic Findings

Chest radiograph shows a large anterior mediastinal mass. The mass is demonstrated as a well-defined lobulated soft tissue lesion with central low density suggesting necrosis and heterogeneous contrast enhancement on contrast enhanced CT scan. There is no detectable mediastinal or hilar lymphadenopathy, and no metastatic focus.

Thymectomy was done. The outer surface of the mass shows diffuse irregular fibrous adhesion. On section of the mass, cut surface reveals partly solid and partly cystic. The cystic area shows hemorrhage and necrosis.

Brief Review

Thymic carcinoids are rare primary malignant thymic neoplasms that affect patients over a wide age range, with the median age being 43 years. Men are more frequently affected than women, with a male-to-female ratio of 3:1. In general, thymic carcinoids exhibit a more aggressive behavior than bronchial carcinoids. This aggressiveness may be related to the fact that most thymic carcinoids are histologically similar to atypical bronchial carcinoids.

The majority of patients present with symptoms related to mass effect on or invasion of mediastinal and other thoracic structures. Presenting symptoms and signs include cough, dyspnea, chest pain, and the superior vena cava syndrome. Approximately one-third of patients are entirely asymptomatic, and the presence of thymic carcinoid is discovered incidentally because of abnormal chest radiographic findings.

Approximately one-half of thymic carcinoids are functionally active and manifest with clinical hormone syndromes. Cushing syndrome is seen in approximately 33%?0% of affected individuals. Another important clinical manifestation relates to the association between thymic carcinoid and the autosomal dominant syndrome of multiple endocrine neoplasia (MEN), specifically type 1 MEN (Wermer syndrome), which is seen in 19%?5% of patients with thymic carcinoids. Additional associated conditions found in patients with thymic carcinoids include type 2 MEN syndrome. There are no reports of the carcinoid syndrome in patients with thymic carcinoids.

Diagnostic imaging of patients with thymic carcinoids usually demonstrates a large anterior mediastinal mass. The lesion may be localized or invasive. Some patients with occult or early thymic carcinoids have normal findings at chest radiography. These individuals may present with clinical evidence of ectopic ACTH production. CT and nuclear medicine imaging have been recognized as useful studies in the evaluation of these patients. Although few reports of cross-sectional imaging features of thymic carcinoid have been published, these lesions have been described as anterior mediastinal masses indistinguishable from thymomas at CT. Invasion of local structures and calcification within the tumor have both been reported. CT and MR imaging studies may be helpful in the evaluation of patients with occult, hormonally active lesions.

Local progression of disease, tumor recurrence, and metastatic disease are common in patients with thymic carcinoids. Thus, the therapy of choice for patients with these neoplasms is complete and aggressive surgical excision of the primary tumor, any recurrent disease, and distant metastases. Thymic carcinoid has an unpredictable behavior and a tendency to metastasize widely and recur locally even years after the initial surgical excision. Thus, adjuvant radiation therapy and chemotherapy have both been employed with some success to treat affected individuals. Although radiation therapy is more commonly used to treat residual and recurrent tumors, the role of chemotherapy is less established.

References

Rosado de Christenson ML, Abbott GF, Kirejczyk WM, Galvin JR, Travis WD. Thoracic Carcinoids: Radiologic-Pathologic Correlation. Radiographics 1999;19:707-736.

Keywords

Mediastinum, Malignant tumor,