[Thymic carcinoid: CT and MR findings]

Area of Science:

• Thoracic imaging
• Oncology
• Endocrinology

Background:

• Thymic carcinoids are rare neuroendocrine tumors arising from the thymus.
• Distinguishing thymic carcinoids from other anterior mediastinal masses can be challenging based solely on imaging.
• Anterior mediastinal masses encompass a differential diagnosis including thymoma, teratoma, thyroid masses, and lymphoma.

Purpose of the Study:

• To analyze the computed tomography (CT) and magnetic resonance (MR) imaging characteristics of thymic carcinoids.
• To compare the morphostructural patterns of thymic carcinoids with other anterior mediastinal masses, particularly those involving the thymic region.

Main Methods:

• Retrospective review of chest CT scans from 1985-1996.
• Inclusion of 4 patients diagnosed with thymic carcinoid (2 female, 2 male; age range 25-51 years).
• MR imaging data available for 3 patients; pathological diagnosis confirmed in all cases via biopsy or surgery.

Main Results:

• CT findings varied: encapsulated, enhanced tumors without spread (1 case); complex masses with necrosis and calcifications invading structures (2 cases); infiltration of mediastinal fat/vessels (1 case).
• One patient presented with superior vena cava/right atrium thrombosis and lung metastases.
• MR showed hypointense T1/PD signals and inhomogeneous hyperintense T2 signals. Endocrine dysfunction (Cushing syndrome, mild adrenocortical hyperfunction) noted in 2 patients.

Conclusions:

• CT and MR imaging patterns of thymic carcinoids are not specific, overlapping with other thymic and mediastinal tumors.
• Clinical and laboratory findings of endocrine dysfunction in the presence of a thymic mass warrant suspicion for thymic carcinoid.