Editing Lung nodules

`A small (<=30mm) well-defined lesion/opacity surrounded by pulmonary parenchyma

* Lesions >30mm are defined as masses, and are much more likely to harbour malignancy, and are generally resected unless obviously benign features

== '''Principles of workup''' ==

* '''Differentiate between benign and malignant'''
* Efficient and cost-effective patient management
* Minimal discomfort and risk of complications

== Approach ==

* Evaluate clinical history and risk factors for likely aetiologies
* Estimate risk of cancer
* Manage based on risk

== Aetiology ==

* Malignant
** Bronchogenic carcinoma
*** Adenocarcinoma
*** SqCC
*** Large cell carcinoma
*** Small cell carcinoma
** Pulmonary carcinoid
** Extranodal lymphoma
** Miscellaneous
*** Plasmacytoma
*** Schwannoma
** Metastatic
*** Breast
*** Head and neck
*** Melanoma
*** Colon
*** Kidney
*** Sarcoma
*** Germ cell tumour
*** Others
* Benign
** Infectious granuloma
*** Histoplasmosis
*** Coccidioidomycosis
*** TB
*** Atypical mycobacteria
*** Cryptococcosis
*** Blastomycosis
** Other infections
*** Bacterial abscess
*** Dirofilaria immitis
*** Echinococcus cyst
*** Ascariasis
*** Pneumocystis jirovecii
*** Aspergillus
*** Septic emboli
** Benign neoplasms
*** Hamartoma
*** Lipoma
*** Fibroma
*** Neurofibroma
*** Leiomyoma
*** Angioma
** Vascular
*** AVM
*** Pulmonary varix
*** Haematoma
*** Pulmonary infarct
** Developmental
*** Bronchogenic cyst
** Inflammatory
*** Granulomatosis with polyangiitis (Wegener's)
*** Rheumatoid nodule
*** Sarcoidosis
** Other
*** Amyloidoma
*** Rounded atelectasis
*** Intrapulmonary lymph node
*** Pseudotumour (loculated fluid)
*** Mucoid impaction
*** Nipple shadow
*** Skinfold
*** Rib fracture
*** Infected bulla

== Clinical history ==

* Vast majority asymptomatic, however look for risk factors and aetiologies
* Risk factors for cancer
** Older age
** Male
** Smoking history
** History of prior malignancy - malignant rate of 64% in new lung nodules, and still 40% if <5mm - hence met until proven otherwise
** Haemoptysis
* Symptoms
** Respiratory symptoms - can occur with centrally located lesions
** Systemic features - B symptoms

== Imaging ==

* Risk factors for cancer
** Nodule diameter
** Spiculation/irregular/lobulated
** Upper lobe location
** Growth rate
** Calcification pattern
*** Benign = diffuse, central, laminated
*** Popcorn pattern = hamartoma
****
*** Indeterminate = punctate, eccentric, or amorphous
** Contrast enhancement (>20HU is likely malignant, <15HU is likely benign)
** Metabolic activity on PET
** Air bronchograms and pseudocavitation - often malignant
***
* Other factors
** Fat-containing nodules are virtually always benign (hamartomas) - malignancies could theoretically be lipomas or RCC mets but very rare
** Benign features - well-defined, smooth, round
** Pulmonary lymph nodes - small, solid, polygonal, perifissural, oval, pleural/septal/vessel attachment
** Halo and reverse halo signs are non-specific and can be seen in both benign and malignant lesions
* Classification
** Solid
** Subsolid
*** Subtypes
**** Pure ground-glass nodules
**** Part-solid/mixed nodules
*** Many subsolid nodules are inflammatory
*** Persistent ground-glass lesions carry a high risk of neoplasm
*** Mixed nodules are highest risk, with a higher solid component meaning higher risk of invasive cancer
**
* CT without contrast, thin slice
** 8-51% of CT shows a lung nodule
** Features
*** Size
*** Attenuation
*** Growth or stable size
**** Growing nodules (>2mm) should be examined pathologically
*** Calcification and fat
* PET
** Best way to evaluate metabolism of indeterminate nodules
** Solid nodules measuring >8mm that are not FDG avid are likely to be benign
** SUV >2.5 is typically used to detect lesions with a high probability of malignancy
** Not as good for subsolid nodules - be aware that slow-growing tumours (adenocarcinomas, carcinoids, low-grade lymphomas, metastases from renal cell carcinoma and mucinous neoplasms) can show little glucose uptake
** Inflammatory lesions are difficult to differentiate from malignant processes on PET

== Initial workup ==

* Assess risk of malignancy as low (<5%), intermediate (5-65%), or high (>65%)
** This is most necessary for nodules 8-30mm in size, since management is generally identical for all nodules at either end of that range
** High-risk features: 
*** Smoking history (OR 7.9)
*** Older age
*** Female sex
*** Family history lung cancer
*** Emphysema
*** Larger nodule size
*** Location of nodule in upper lobe
*** Part-solid nodule type
*** Lower nodule count
*** Spiculation
*** Prior malignancy (met unless proven otherwise)
*** Asbestos exposure
* Assess with imaging


'''Factors that influence the management of nodules 8 to 30 mm in size'''
{| class="wikitable"
|'''Factor'''
|'''Level'''
|'''CT scan surveillance'''
|'''PET imaging'''
|'''Nonsurgical biopsy'''
|'''VATS wedge resection'''
|-
|'''Clinical probability of lung cancer'''
|Very low (<5%)
|<nowiki>++++</nowiki>
|–
|–
|–
|-
|
|Low-moderate
|<nowiki>+</nowiki>
|<nowiki>+++</nowiki>
|<nowiki>++</nowiki>
|<nowiki>+</nowiki>
|-
|
|High (<65%)
|–
|(± staging)
|<nowiki>++</nowiki>
|<nowiki>++++</nowiki>
|-
|'''Surgical risk'''
|Low
|<nowiki>++</nowiki>
|<nowiki>++</nowiki>
|<nowiki>++</nowiki>
|<nowiki>+++</nowiki>
|-
|
|High
|<nowiki>++</nowiki>
|<nowiki>+++</nowiki>
|<nowiki>++</nowiki>
|–
|-
|'''Biopsy risk'''
|Low
|–
|<nowiki>++</nowiki>
|<nowiki>+++</nowiki>
|<nowiki>+++</nowiki>
|-
|
|High
|<nowiki>++</nowiki>
|<nowiki>+++</nowiki>
|–
|<nowiki>+</nowiki>
|-
|'''High suspicion of active infection or inflammation'''
|
|–
|–
|<nowiki>++++</nowiki>
|<nowiki>++</nowiki>
|-
|'''Values and preferences'''
|Desires certainty
|–
|<nowiki>+</nowiki>
|<nowiki>+++</nowiki>
|<nowiki>++++</nowiki>
|-
|
|Risk averse to procedure-related complications
|<nowiki>++++</nowiki>
|<nowiki>+++</nowiki>
|<nowiki>++</nowiki>
|–
|-
|'''Poor adherence with follow-up'''
|
|–
|–
|<nowiki>+++</nowiki>
|<nowiki>++++</nowiki>
|}

== Specific guidance ==

* Size-based
** Nodules >3cm should be treated as bronchogenic carcinoma until proven otherwise
** Nodules <=8mm without documented growth are often followed with serial CT
** Nodules <=5mm have a malignancy rate of 1%, whereas those >2cm have a rate of up to 82%
* Growth-based
** Volume doubling in <20 days is considered indicative of infectious or inflammatory processes
** Volume doubling between 20 and 400 days is suspicious for malignancy
** Stability over >400 days implies benign process (granuloma or hamartoma), and nodules stable over 2 years are considered clinically benign (beware that some adenocarcinomas can be very slow-growing - be more careful with subsolid lesions)
** Malignant nodules can decrease in size due to necrosis/fibrosis, however all malignant lesions will grow over a long enough time period
* Indeterminate lung nodules >1cm should be assessed with FDG-PET/CT
** Likelihood of malignancy increases as SUV-max increases
** Small lesions <1cm are challenging to pick up on PET
* Solid lesions stable for 2 years and subsolid lesions stable for 5 years are likely to be benign, and can be signed off on
* Recent pneumonia - repeat the scan in 4-6 weeks, provided no other concerning features
* Lots of systemic features but small nodule - suspect metastases or lymphoma
* Multiple nodules - consider metastatic disease, reaction to chemotherapy, secondary infection in immunosuppressed patients, other inflammatory process - if no concerning features, may be appropriate for repeat scan in 3-6 months

== Management based on Fleischner guidelines (2017) ==

* Eligibility criteria
** >35yo
** Has never had known or suspected cancer at any site
** Not immunosuppressed
* Define risk status
**





== Options for biopsy: ==

* Diagnostic bronchoscopy
** Good for central lesions >20mm or for lesions with a visible bronchogram reaching into the nodule - yield 80% when these features are present, 34% when not
* Navigational bronchoscopy
* EBUS
* Trans-thoracic needle aspiration
** Risks:
*** PTX (overall 20-50%, requiring percutaneous drainage 10%)
*** Bleeding
*** Infection
*** Gas embolism
*** Tumour seeding
** FEV1 >1L considered safe for biopsy, but beware of patients with pulmonary fibrosis who may have a lower reserve than predicted by FEV1
* VATS and sub-lobar resection with frozen section
** Indicated in peripheral lesions with high probability of malignant disease
** For small lesions far from pleural surface, pre-operative localisation techniques can be used
** Intra-operative USS can also help
* VATS and lobectomy
* Pneumonectomy 
** Should not be performed without a cancer diagnosis




[[Category:Thoracics]]