Peripheral pulmonary carcinoid tumor

Last revised by Dr Yuranga Weerakkody on 22 Sep 2022

Peripheral pulmonary carcinoid tumor refers to a subtype of pulmonary carcinoid tumors that arise within the periphery of the lung. They are considered less common than the more centrally-located bronchial carcinoid tumors

Many patients tend to be asymptomatic  2. Presentation with carcinoid syndrome is extremely rare 6

Peripheral pulmonary carcinoid tumors are considered a neuroendocrine tumor of the lung. They can be

  • smoking: the rate of carcinoid tumors is similar between smokers and non-smokers, although there is an increased incidence of atypical subtype amongst smokers 5,6

Most are discovered as an incidental rounded solitary pulmonary nodule. The size at diagnosis can vary but is usually reported to be in the range of 10-30 mm 2. Many have a lobulated margin with an average Hounsfield value on post-contrast imaging of ~50 2. Imaging features are often non-specific and tissue diagnosis is essential in determining diagnosis.

Most peripheral carcinoid tumors tend to involve a subsegmental bronchus 2

Calcification may be present in a small percentage (~11% )of tumors2.

Some authors had suggested a ‘bronchial triangle sign’ which may assist in diagnosis 12.

May have a sensitivity of around 75% 7. Although most cases will show uptake on an 18-FDG PET, up to a quarter of false-negative has been described 2

Usually avid and useful for diagnosis 8.

Some authors consider there as complex tumors as a whole which require a multidisciplinary approach and long-term follow-up 10.

In some situations for CT appearances consider 

For a broader differential see differentials for a solitary pulmonary nodule

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Cases and figures

  • Case 1: typical
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  • Case 2
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