notes by dr Claudio Italiano
The stratification of patient risk takes on critical importance to define the
probabilities of a carcinoma.
This stratification must be carried out before any examination is carried out.
To this end, numerous models have been developed and validated, which estimate
the probability of malignancy of the nodules based on factors such as:
- age of the patient
- cigarette smoke
- the neoplastic history
-the size, shape and location of the nodules.
The differential diagnosis is made towards other lesions, usually phlogistic,
tuberculous, mycetomas, luetic rubbers and, above all, in the nodules related to
the pulmonary interstitial pathologies, very widespread.
- Calcific lung abscess
- tuberculoma
- luetic rubber
- mycetoma
- parasitic
- asbestosis
- incident nodules of interstitiopathies, in pneumoconiosis, are small and
multiple nodules, with a ground-like lung.
- nodules in the course of anthracosis (accumulation of coal dust)
- asbestosis
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solitary pulmonary nodules
Solitary nodules of the lung can be followed with imaging tests such as chest
radiographs, computed tomography (TQ tomography with positron emission with
fluorine-deoxy-glucose (fluorodeoxygIucose -positron emission tomography,
FDG-PET).
The choice of imaging modality is based on the guidelines formulated by ACCP.
Some concepts can be drawn from this review. To exclude false-positive results,
chest radiographs should always be evaluated in different projections. To
evaluate the initial appearance of the nodule and to determine the doubling time
of its size, a review of previous available radiographic examinations is useful.
The chest radiograph is potentially able to display nodules of a diameter of up
to 5-6 mm; however, the method presents a high rate of false-negative results.
Up to 20% c of non-small cell lung carcinomas are retrospectively identified in
the reexamination of chest radiographs that were initially considered normal.
The chest CT scan has higher specificity and sensitivity than radiography.
The CT also allows an assessment of surrounding structures. All patients with a
solitary nodule of the lung that is poorly characterized on chest radiographs
must undergo a CT scan.
CT is the imaging modality of choice to re-evaluate pulmonary nodules previously
identified on the chest radiograph, as well as to follow the nodules as a
function of time, in order to evaluate any changes in size.
PET-FDG is a method of non-invasive imaging that is typically used in the field
of oncology for the diagnosis, staging and evaluation of the response to
treatment of various neoplastic forms. FDG is selectively captured by malignant
tumor cells, allowing its visualization by PET
In the lung parenchyma window we can evaluate the following characteristics of
a NP:
Dimensions
Margins (smooth, lobulated, irregular, spiculated)
Form (spherical, not spherical)
Density (solid, partially solid, to "frosted glass")
In the mediastinal / soft tissue window we can evaluate the following
characteristics of an NP:
Fat components
Calcifications (diffuse, central, "pop corn", laminar, pinpoint, eccentric)
Post-contrast enhancement
The 2017 Fleischner Society (2017) guidelines on NP management of solitary
lung nodules provide two distinct algorithms for setting patient follow-up.
The choice between the two algorithms depends on the size of the nodule, less
than 8 mm or greater than or equal to 8 mm, with an increased probability of
malignancy of the lesions.
The rationale of the new guidelines is based on the assumption that the
follow-up of one or more incidental nodules should be performed only if the
probability of malignancy is greater than or equal to 1% for which it is not
recommended in the nodules, both solids and not solid, smaller than 6 mm even
in high-risk patients.
They are considered risk factors for malignancy of an NP:
- seat in the upper lobes,
- spiculated margins,
- smoking,
- old age,
- familiarity with pulmonary neoplasm.
In summary, for solid NPs of 6-8 mm, in patients at low risk, only one follow-up
examination (6-12 months) is usually sufficient, in case of stability; in the
case of nodules of suspected morphology or of uncertain stability, a further
check at 18-24 months from the baseline can be indicated.
For 6-8 mm solid NPs, in patients at high risk, a follow-up examination at
6-12 months and a follow-up at 18-24 months is required. The second test is
usually sufficient, in case of certain stability, to exclude the risk of
neoplasia; in the case of nodules of suspected morphology or of uncertain
stability a further check may be indicated.
For solid NPs> 8 mm, regardless of the risk, a three-month CT scan may be
proposed, or alternatively a TC-PET assessment or a biopsy
The guidelines also apply to patients who can not undergo surgery.
Since the only potentially definitive treatment of lung cancer is surgical
excision, the algorithm recommends a more limited evaluation in these patients.
For patients with nodules smaller than 8 mm, specific follow-up protocols are
recommended based on the size of the lesion: less than 4 mm, between 4 mm and
less than 6 mm, between 6 mm and less than 8 mm.
The indication to interrupt the follow-up after 2 years is based on the fact
that the malignant pulmonary nodules typically have a doubling time of less
than one year; therefore, a stable lesion at a 2-year follow-up, without
suspected morphologic features and in a low-risk patient may be considered
benign.
In high-risk patients with stable lesions of less than 8 mm, the performance
of FDG PET may also be considered; this indication is not however specifically
provided for in the guidelines.
Two nodular neoplastic lesions are visible at the right lung, under the
port-au-cath, personal case
Due to the reduced sensitivity of the method in the evaluation of lesions
smaller than 8-1 0 mm.
All patients with nodules showing substantial growth during follow-up, or with
positive results (high metabolic activity) to FDG-PET should undergo further
evaluation, typically with surgical biopsy, needle biopsy or bronchoscopy.
As discussed above, patients with nodules larger than 8 mm are followed
according to a different algorithm.
The nodules should initially be evaluated by comparison with previous imaging
exams, so as to be able to determine any changes in their size as a function
of time.
Nodules of stable size for more than 2 years can be followed without any
intervention, with the exception of cases in which morphological evaluation
suggests malignancy (eg frosted glass opacity, irregular margins).
In patients who can not undergo surgery, however, a biopsy can be considered,
to define a diagnosis, and radiotherapy or palliative care can be undertaken.
The follow-up protocol of potential patients for surgical intervention is
defined based on the pre-test probabilities of the malignancy of the nodule (using
the predictive model, discussed above, based on risk factors: age of the
patient; cigarette smoke, previous history of carcinomas, size, morphology and
location of the nodule). "
This assessment allows a risk stratification: high probability of malignancy (over
60%); low probability (less than 5%); intermediate probability (between 5 and
60%), which affects the majority of patients. To subdivide these patients into
a low-risk group and a high-risk group, further tests are required.
cfr index pneumology