Duke Internal Medicine Residency Curriculum
The Solitary Pulmonary Nodule
Author: Andrew Hope, MD
Editor: Amy Shaheen, MD, Assistant Professor
of Clinical Medicine
Duke University Medical Center
Copyright © 2005, Duke Internal Medicine Residency Curriculum and DHTS Technology Education Services
Duke Internal Medicine Residency Curriculum
Pulmonary Nodule: Definition & Incidence
• Definition:
– Approximately round lesion that is less than 3 cm in
diameter, completely surrounded by aerated lung.
– >3cm is a mass, highly likely to be malignant
– Incidence of malignancy among SPN is widely
variable in case series (10-70%)
• Incidence:
– 0.09-0.20% of routine CXRs have a solitary
pulmonary nodule (SPN)
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Pulmonary Nodule: Differential Diagnosis
• Benign (70% of time in
non-known CA pts)
– Infectious granuloma (i.e.
histo, cocci, TB, atypical
mycobacteria, crypto,
blasto)
– Benign neoplasm, i.e.
hamartoma, lipoma
– Other infection, i.e.
abscess, echinococcal
cyst, aspergillus, etc
– Causes of benign lesions:
Infectious granulomas,
80%. Hamartomas, 10%.
• Malignant
– Bronchogenic
carcinoma
– Metastases, i.e.
breast, head/neck,
melanoma, colon,
renal cell
– Carcinoid
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Pulmonary Nodule: Diagnostic Modalities
• Diagnostic modalities:
– High resolution (remember this when ordering!) chest CT
scans—initial test of choice.
– CT scan with contrast—dependent on institution
– MRI (only for patients who cannot get IV contrast; no better
than CT!)
– PET scan. Used for patients with intermediate probability of
malignancy— good choice for excluding malignancy in many
patients without obvious treatment plan. Useful only for
lesions >1cm, where it has a 97% sensitivity. Expensive;
Medicare recently reimbursed $1912 for PET vs $276 for CT.
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Pulmonary Nodule: Radiographic characteristics to evaluate
• Radiographic characteristics to evaluate for
malignancy:
– Associated with benign process
• Stability in size over 2 years—highly associated with benign
disease
• Calcification in the correct pattern more likely benign (i.e., diffuse,
laminar/”popcorn”, or central)
– Assoc. with malignancy
• Spiculation or “corona radiata sign”, 4-5 mm linear strands
radiating from lesion
• Change in size: doubling time for cancer usually >1 month and
<1 year
• Larger size (>2.3cm)
• Upper lobe location
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Pulmonary Nodule: Patient characteristics to predict malignancy
•
Patient characteristics to predict malignancy:
–
See table from Ost D et al, NEJM 2003. Age and smoking status, as well as previous
cancer history are important patient characteristics.
Click here for
.pdf file of this
table
Copyright © 2005, Duke Internal Medicine Residency Curriculum and DHTS Technology Education Services
Duke Internal Medicine Residency Curriculum
Pulmonary Nodule: Decision for Surgery
•
Decision for surgery:
– In general, the decision for surgery takes into account the risk of malignancy
compared to the risk for surgery. If the risk/benefit ratio is acceptable taking
into account patient comorbidities, cancer risk profile, and available
radiographic data including PET scan, the patient should be referred for VATS.
The initial surgical approach is usually excisional biopsy with wedge resection
and removal of the nodule. If frozen sections indicate malignancy, the
surgeon will proceed to lobectomy with mediastinal lymph node dissection at
the same time.
•
Use of decision analysis to identify surgical candidates
– Sophisticated mathematical models using likelihood ratios and baseline patient
risk have been developed to predict the percentage likelihood of cancer in a
given patient with a SPN. The details of three models are available on UTDOL.
However, given the models’ complexity and the fact that patient preference
should guide therapy, institutional protocols still vary in approach.
Copyright © 2005, Duke Internal Medicine Residency Curriculum and DHTS Technology Education Services
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Pulmonary Nodule: Patients with High Surgical Risk
• Patients with high surgical risk.
– Patients with high surgical risk present more difficulty, and
unfortunately surgical risk tends to cluster with the patients who are
more likely to have malignancy (i.e. smokers, the elderly). For these
patients, a biopsy can help guide whether surgical risk is worth
taking:
• TTNA. Best for patients who are not surgical candidates, to make tissue
diagnosis. Variable sensitivity—does not rule out malignancy.
• Bronchoscopy. Best for central/endobronchial lesions or mediastinal LAD.
Again, able to rule in malignancy, but not rule it out.
• Follow up for patients not referred for surgery:
– Serial high resolution CT scans should be performed at 3, 6, 9, 12,
18, and 24 months to rule out enlargement of the nodule or
development of new nodules.
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Pulmonary Nodule: Proposed algorithm for approach to SPN
•
Click here for
.pdf file of this
algorithm
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Pulmonary Nodule: Question (1)
A 62 y/o woman is evaluated because of abnormal
results on chest radiograph. She smokes 1 pack of
cigarettes per day, with a 50-pack-year history. She
has a morning cough productive of small amounts of
yellow sputum. She has hypertension, for which she
takes metoprolol, and type 2 diabetes mellitus, which
is managed with diet and metformin therapy.
Her BMI is 30. Her BP is 145/90 mmHg. Chest
radiograph shows a 1.5cm nodule in the left upper
lobe; no previous radiographs are available for
comparison.
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Pulmonary Nodule: Correct Answer rationale 1
D) PET scanning uses 2-fluoro-2-deoxy-D-glucose (FDG) as the positron
emitter and measures the relative concentration of the agent in the nodule.
Because FDG competes with glucose for uptake into the nodule, elevated
serum glucose can lead to a false-negative test. It is, therefore, important that
patients with diabetes mellitus have good serum glucose control before PET
scanning.
The cell type of the tumor is not important in the imaging, and lesions larger
than 1 cm can be assessed by PET scanning. Blood pressure control, has no
influence on PET imaging, and the study is not potentially nephrotoxic because
it does not use radiocontrast agents. (MKSAP-13)
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Pulmonary Nodule: Question (2)
A 38 y/o woman who has never smoked is evaluated
because of a well-circumscribed nodule in the right
lower lobe, which was discovered on a chest
radiograph during a routine physical examination.
There is no family history of cancer, the patient has
never had cancer herself, and the lesion is completely
calcified. A CT scan of the chest done 2 years ago
showed a 0.8cm nodule in the right lower lobe.
Another CT scan is ordered, and it shows the nodule
is eccentrically calcified and has grown.
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Pulmonary Nodule: Correct Answer rationale 2
D) This patient likely has a benign granuloma, which is growing. The
characteristics of the nodule, well-circumscribed, lower lobe location make it
less likely to be a malignancy. In addition, the patient’s young age, the fact
that she has never had cancer, and the fact that she is a nonsmoker also make
cancer unlikely. The nodule should be removed.
TTNA is unhelpful because a negative aspirate would not rule out the clinical
suspicion of cancer. A PET scan would be a reasonable option if the lesion
were larger; PET scanning cannot discriminate well is the lesion is less than
1cm.
Lobectomy is too extensive if the lesion is not malignant. Removal of the
nodule allows for minimal resection; if the frozen section at the time shows
cancer, then a formal lobectomy can be accomplished during the same surgery.
(MKSAP-13)
Copyright © 2005, Duke Internal Medicine Residency Curriculum and DHTS Technology Education Services
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Pulmonary Nodule: Sources
• Ost D, Fein AL, and Feinsilver SH, “The Solitary Pulmonary
Nodule”, NEJM 2003;348(25): 2535-2542.
• Tan BM, Flaherty KR, et al., “The Solitary Pulmonary Nodule”,
Chest 2003;123(1 supp):89S-96S.
• UTDOL, 2005
Copyright © 2005, Duke Internal Medicine Residency Curriculum and DHTS Technology Education Services