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Carcinoid

John Walter Millstine, MD - Case Coordinator
Kemi Babagbemi, MD - Radiology Discussion
Gerald P Bailey, MD, PhD - Pathology Discussion
Francine Jacobson, MD - Attending Radiologist
Pablo R Ros, MD, MPH - Attending Radiologist

June 10, 2002

Presentation

A 44-year-old man presented for additional imaging following an incidental finding on a routine chest film.

Imaging Findings

AP and Lateral Radiographs
Computed Tomography
Gross Pathology
Histology

On the anteroposterior radiograph, a relatively homogeneous, well-circumscribed mass is seen overlying the right heart border. Neither associated lymphadenopathy nor pleural effusions are evident. On the lateral radiograph, the mass is also visible. The mass appears to be in the right middle lobe or right hilar area.

On computed tomography (CT) images, the mass is seen to have heterogeneous attenuation. Calcification is also evident, along with low-density areas. No evidence of lymphadenopathy is visible on CT. There is a component of the mass that is within the bronchus.

Differential Diagnosis

The differential diagnosis could include neoplastic, infectious, or congenital processes. The endobronchial component may be indicative of endobronchial carcinoma that has invaded beyond the bronchial wall into lung parenchyma. Calcification could be seen in squamous cell cancer, though this would be rare. CT is an important imaging modality for this case because it indicates the mass is solid rather than cystic. Because this mass is solid, it is most likely malignant. In a patient of this age, very few primary lung tumors are likely to be found. Carcinoid is one of the few tumors that might commonly be detected in a patient so young. In addition, the endobronchial component and dystrophic calcification seen in this patient are characteristic of carcinoid. This lesion is, however, unusually large for a carcinoid.

Diagnosis

Carcinoid

Discussion

Pathology Discussion

The right middle and lower lobe were resected. On a cross-sectional image of the right middle lobe, a well-circumscribed 7-cm mass is visible. The mass is focally hemorrhagic and contains some calcifications. It abuts the pleura and the bronchus; the endobronchial component (not pictured) extended from the secondary to the primary bronchus.

Carcinoid is a well-differentiated neuroendocrine carcinoma. It can occur in many forms: solid mass, ribbon-like, and pseudo-glandular shapes have been described. Regardless of the shape, the cells are fairly monotonous and similar in size. The histology reveals a centrally located nucleus and cytoplasm marked by neuroendocrine granules, resulting in a characteristic "salt-and-pepper" appearance.

Radiology Discussion

The differential diagnosis for a mass in the airway includes carcinoid and mucoepidermoid carcinoma (usually occurring in the bronchus) and adenoid cystic carcinoma (usually occurring in the trachea). Carcinoid most commonly involves the gastrointestinal tract, but can also involve the thymus, lung, biliary tract, and/or ovaries. These tumors account for only 0.6-2.4% of pulmonary neoplasms.

Carcinoid tumors arise from neuroendocrine (Kulchitzky) cells in the airway. Tumors of this cell origin may fall anywhere along the spectrum ranging from typical carcinoid to atypical carcinoid to highly malignant small cell carcinoma. In typical carcinoid, a low-grade malignancy, the 5-year survival rate is 95%. Its incidence is equivalent in men and women, and the median age of presentation is 50 years. The classic carcinoid syndrome is seen with liver metastases from GI primaries and occurs in less than 3% of typical lung carcinoid cases. Atypical carcinoid is characterized by a larger, more aggressive tumor with irregular margins and early metastases (typically blastic bony metastases). It usually presents at a median age of 60 years. This type of carcinoid is commonly associated with regional adenopathy. Patients presenting with associated adenopathy only have a 5-year survival rate of 70%. If metastases are also present, the prognosis drops to 50%. With both typical and atypical carcinoid, the symptoms generally include cough, hemoptysis, wheezing, and recurrent areas of atelectasis.

When carcinoid tumors are detected in the lungs, 83% are associated with the bronchus. The tumor itself may be:

Less often, carcinoid may occur as a solitary pulmonary nodule. These solitary tumors are most commonly found in the right upper and right middle lobes.

On CT, carcinoid tumors appear as central tumors in 80% of patients. The masses show marked enhancement, due to high vascularity that also results in a fleshy, cherry red appearance on bronchoscopy. Peripheral punctate calcification or ossification, which may not be visible on radiography, is found on CT in about 10% of cases. Areas of atelectasis, bronchiectasis, mucoid impaction, and lymphadenopathy are also common findings.

References

Abbott GF. Uncommon Tumors of the Lung , Part I. In: AFIP Syllabus notes, chest section.

Brant WE, Helms C, eds. Fundamentals of Diagnostic Radiology. Chicago: Williams and Wilkins; 1999:396-397.

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