Thymic Neuroendocrine Carcinoma

Thymic neuroendocrine carcinoma is a type of thymic epithelial neoplasm (see this term) displaying evidence of neuroendocrine differentiation.

Epidemiology

The exact prevalence or incidence is unknown. Thymic neuroendocrine carcinomas represent 2-4% of the anterior mediastinal tumors. More than 300 cases have been reported to date. Men are predominantly affected.

Clinical description

Many of the patients are asymptomatic but some present with chest-related symptoms such as cough, chest pain, weight loss, fatigue and dyspnea. Cushing's syndrome, multiple endocrine neoplasia, and, rarely, carcinoid syndrome (see these terms) are associated with this type of tumor.

Etiology

Etiology is unknown.

Diagnostic methods

Diagnosis is based on clinical findings, radiological studies (chest X-rays, computed tomography, magnetic resonance imaging (MRI), angiography (angio-MRI) and/or positron emission tomography (PET)), and on tissue biopsy, usually performed by CT- or ultrasound-guided percutaneous needle-biopsy. Three histological subtypes are observed: well-differentiated neuroendocrine carcinoma (formerly known as ''thymic carcinoid''), moderately-differentiated neuroendocrine carcinoma (formerly known as ''atypical carcinoid''), and poorly-differentiated neuroendocrine carcinoma (also known as small cell carcinoma of the thymus).

Differential diagnosis

Differential diagnosis includes lymphoma, germ-cell tumors (see these terms), and other primary thymic malignancies and metastatic cancers.

Management and treatment

Treatment consists of total thymectomy and complete tumor excision usually accompanied by post-operative radiotherapy and chemotherapy.

Prognosis

Thymic neuroendocrine carcinomas are aggressive tumors with a poor prognosis. Prognosis is dependent on the histological subtype with well-differentiated neuroendocrine carcinoma being the least aggressive subtype and poorly-differentiated neuroendocrine carcinoma being the most aggressive subtype with a median survival of 18 months. Recurrences and metastases are frequently observed. The 10-year survival is between 10% and 28% and depends on the treatment.