A 40-year-old male smoker presented to his primary care physician
for persistent chest-wall pain following a mild sports injury. He
also complained of worsening exertional dyspnea and night sweats.
There was no report of significant surgical or medical history. The
physical examination was unremarkable except for some minor
chest-wall tenderness. Anteroposterior and lateral chest films were
obtained (Figure 1). Based on these findings, a contrast-enhanced
computed tomography (CT) study was performed (Figure 2).
Diagnosis
Typical bronchial carcinoid tumor
Findings
Anteroposterior (Figure 1) and lateral chest radiographs revealed a
large (3- to 4-cm) mass at the posterior aspect of the left hilum.
Contrast-enhanced CT scan of the chest revealed a large mass in the
superior segment of the left lower lobe, with associated left hilar
and subcarinal adenopathy (Figure 2). 18F-flourodeoxyglucose
positron emission tomography (PET) revealed a nonavid mass,
excluding the possibility of a bronchogenic carcinoma (not shown).
Bronchoscopy revealed a mass within the superior segmental bronchus
of the left lower lobe (Figure 3), from which a biopsy was obtained
for pathologic identification (Figure 4). After the diagnosis was
established, the patient underwent a successful left pneumonectomy.
Histologic examination of the tumor was consistent with typical
carcinoid tumor (Figure 5).
Discussion
Carcinoid tumor is a serotonin-producing malignant tumor belonging
to a class of neoplasms known as the neuroendocrine tumors. They
are unique in that they can present with tumor-like symptoms or
with a combination of symptoms related to endocrine dysregulation.
Most cases of carcinoid are found incidentally in the appendix
following an appendectomy. The prevalence of carcinoid in the
general population is actually quite high, but >95% of these
tumors occur in one of three sites: the appendix, rectum, or small
intestine.
1,2
Carcinoid tumors of the lung are much less common and represent
1% to 2% of all lung cancers.3 They arise from the
neurosecretory cells of the bronchial mucosa. Two different types
have been identified.4 The first and most common is
referred to as typical carcinoid. Typical carcinoid tumors are
low-grade tumors, with 10-year survival rates approaching
90%.5 They are capable of local invasion, including
invasion of local lymph nodes, but rarely metastasize. The second
type of carcinoid is referred to as atypical carcinoid. It is much
more aggressive and carries a 5-year survival rate of 25% to
69%.6 Both subtypes tend to arise from the bronchial
tree and spread by local invasion. Typical carcinoid tumors are
more commonly found centrally within the major bronchi, whereas the
atypical carcinoids tend to arise from the peripheral and central
bronchi with equal frequency.7 The most frequently
presenting symptoms of carcinoid are lobar obstruction, hemoptysis,
dyspnea, cough, and lobar pneumonia secondary to obstruction. Some
are found serendipitously on chest radiographs in asymptomatic
patients; rarely, patients may present with endocrine
abnormalities, such as Cushing's syndrome.8 Both types
of carcinoid tumors of the lung can occur in patients of any age,
without gender preference. The role that smoking plays in the
development of carcinoid is still under debate.5
Definitive diagnosis and classification is made by biopsy and
pathologic examination of the tissue. Due to its predilection for
arising from the luminal surface of the major bronchi, adequate
tissue samples can often be obtained through endobronchial biopsy.
Alternatively, tissue may be obtained through CT-guided fine-needle
biopsy or thoracotomy.7
Helical chest CT is helpful in determining the size and position
of the tumor but is not as accurate in assessing tumor extension as
high-resolution CT (HRCT).9 Helical chest CT may also
help in narrowing the differential diagnosis, by identifying
characteristic findings of carcinoid. These findings include dense
ossification, scattered calcifications, and intraluminal
location.10 Since carcinoid tumors are metabolically
sluggish relative to most other malignancies, PET imaging is most
often negative. These results can be misleading, because it may
falsely suggest that the lesion is benign.11
Carcinoid is treated surgically, with the approach dependent on
the size, location, and tissue type. Treatment for intraluminal
typical bronchial carcinoid may be attempted with bronchoscopic
removal of the tumor. This technique combines direct bronchoscopic
visualization with HRCT. Bronchoscopic removal of these tumors
leads to complete eradication in the majority of
patients.9 Tumors not meeting the criteria for
endobronchial resection may be treated surgically with bronchial
sleeve resection, segmentectomy, lobectomy, or
pneumonectomy.8 Chemotherapy has not been demonstrated
to be successful as a treatment option but, rather, is limited to a
palliative role in the management of diffuse metastatic carcinoid;
however, investigations involving chemotherapy are still
ongoing.12-14
CONCLUSION
Bronchial carcinoid tumor is a low-grade malignant tumor with
slow progression and is associated with a favorable prognosis.
There are two subtypes, with the less aggressive type comprising
approximately 90% of all bronchial carcinoids. The definitive
diagnosis is made by histologic examination. Carcinoid tumors
typically arise from the luminal surface of major bronchi, and
definitive treatment involves surgical resection.
Prepared by Douglas W. White, MD and
Justin Q. Ly, MD from the Department of Radiology,
Wilford Hall Medical Center, Lackland AFB, TX; Douglas P.
Beall, MD from the Department of Radiology and Nuclear
Medicine, Uniformed Services University of Health Sciences,
Bethesda, MD; Joseph H. McDermott, MD from the
Department of General Surgery, Wright-Patterson Medical Center,
Wright Patterson, OH; and James A. Graham, MD,
from the Department of Pulmonology, Wilford Hall Medical Center,
Lackland AFB, TX.
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