Solitary pulmonary nodule

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Solitary Pulmonary Nodule

DR.BHARAT SINGH DMRD-1st YEAR SNMC AGRA

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DEFINITION A solitary pulmonary nodule (SPN) is a round or oval opacity smaller than 3 cm in diameter that is completely surrounded by pulmonary parenchyma and is not associated with lymphadenopathy, atelectasis, or pneumonia.

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INCIDENCESPN is found in 1-2% of all CXR

Geographic variations in the incidence of benign lesions, especially infectious granulomas

No sex difference in incidence

Solitary nodules can occur at all age

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Conti.Smokinghistory Prior history of malignancy Travel history - Travel to areas with endemic mycosis (eg, histoplasmosis, coccidioidomycosis, blastomycosis) or a high prevalence of tuberculosis Occupational risk factors for malignancy - Exposure to asbestos, radon, nickel, chromium, vinyl chloride, and polycyclic hydrocarbons Previous history of tuberculosis or pulmonary mycosis

ETIOLOGYCongenital TraumaticBronchogenic cysts hematomaAVM (congenital arteriovenous malformations)Bronchial atresia

Infective NeoplasticTB, round pneumonia Bronchogenic ca. Fungal CarcinoidHydatid PlasmacytomaAbscess MetastasesMiscellaneous Lymphoma Wegeners granulomatosis Adenoma, hamartomaRAAmyloidosis ARTEFACTSRounded atelectasis

SPN - Etiology40% of spn are malignant, with other common lesion being granuloma and benign lesion Benign80% infectious granulomas10% hamartoma10% non-infectious granulomas, benign tumoursMalignant25% metastatic75% bronchogenic carcinoma and carcinoid

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SIMULANTS OF SPNExtra thoracic artefactsCutaneous masses nipple, lipoma ,NFBony lesions island, healing #, sclerotic lesionPleural tumors / plaquesEncysted pleural effusionPulmonary vessels

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MODALITIES USEDPLAIN radiographyCT NCCT, CECTPET WITH FDG-F18PET- CTFNAC / BIOPSY

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TWO ISSUES

Lesion detection

Lesion characterization benign versus malignant

LESION DETECTED ON CHEST XRAY Pick up depends upon experienceOver reading/ under readingHigh Kv better rate of detectionDigital radiographs- allow manipulation on a computer monitor Always compare current radiographswith previous radiographs

LESION DETECTED ON CXRSPNs are discovered first as incidental findings on chest radiographsThe first step is to determine whether the nodule is pulmonary or extra pulmonaryA lateral chest radiograph, fluoroscopy, or CT of the chest often helps determine the location of the nodule>8-10 mm Nodules are identifiable by chest radiographsOccasionally, SPNs can be visualized at 5 mm in diameter

Internal Characteristics

Size MarginCalcificationFatCavitationAir bronchograms or bubbly lucencies

SIZEThe size of the mass is of little diagnostic valueOnly a small percentage of nodules under 1 cm in diameter are malignent.

MARGIN

Small nodule with smooth margin suggestive of benign but not diagnostic of benign lesionLobulated contourIrregular margin typical malignant lesionSpiculating margin Adjacent tiny nodules, called satellite nodules, may mimic the appearance of a lobulated and the presence of these nodules is strongly associated with benign nature

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Smooth margin - benign

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CalcificationSuggestive of benign SPN Central, solid Laminated Popcorn -1/3 rd of hamartoma Diffuse Suggestive of Malignant SPN 6-14% of malignant nodules are calcified on CT Eccentric Stippled

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Solitary Pulmonary NoduleCalcification

A stippled appearance or psammomatous calcification can be seen in SPNs that are metastases from mucin-secreting tumours such as colon or ovarian cancersDense foci of calcification or be entirely calcified,with a pattern resembling that of benign Disease can be seen in carcinoid, metastatic osteosarcoma and chondrosarcoma

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Pattern of calcificationCentral = granuloma

Nodule completely calcified = granuloma

Target = histoplasmosis

Popcorn = hamartoma

ECCENTRIC CALCIFICATION

ECCEN

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Central calcification

CAVITATIONSPNs with irregular-walled cavities thicker than 16 mm tend to be malignant Benign cavitated lesions usually have thinner, smooth wall Up to 15% of lung cancers form a cavity, but most are larger than 3cm in diameter

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THICK WALLEDTHIN WALLED

Air bronchogramAir bronchograms are seen more commonly in pulmonary carcinoma than in benign nodules Air bronchograms were seen in approximately 30% of malignant nodules but in only 6% of benign nodules Air bronchograms is due to desmoplastic reaction to the tumour that distort the airway

HAMARTOMA 50% of hamartomas have fat 30% of hamartomas have calcification (popcorn appearance) Middle-aged adults, slow growth ,90% in intra pulmonary and within 2cm of pleurafat is present in the nodule , hamartoma or lipoma become most likely cause , Metastasis from lipo sarcoma, RCC, may occasionally contain fatIn patient without prior malignancy, focal attenuation (-40to-120) is reliable indicator of hamrtoma.

HAMARTOMA

INFECTIONtuberculoma: most common in upper lobe well defined and lobulated , calcification frequent , 80% have satellite leison Cavitation is uncomman HistoplasmosisMost frequent in lower lobeWell defined / seldom larger than 3cmCalcification common and central target appearanceCavitation are rare

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HYADIT CYSTMost common right lower lobeCommon in endemic area Well defined , 1-10 cm in sizeRupture result in water lilly sign

vascularAVM: Well defined and lobulated- Bag of worm appearence dilated feeding arteries and draining vein may be visible 66% are single, calcification is rareHematoma peripheral ,smooth and well defined slow resolution over several weeksPulmonary infarction Most frequent in lower lobe wedge shaped area of consolidation can be identified abutting the pleura , small u/l or b/l pleural effusion is seen

AVM

AVM WITH FEEDING VESSELS

CONGENITALPulmonary sequestration usually more than 6cm in diameter 2/3rd in left LL ,1/3rd in rt LL well defined round or oval lesionConfirmed by aortography and venous drainage is via pulmonary vein or bronchial veinBronchogenic cyst well defined, round or oval in shaped ,smooth wall 2/3rd are intrapulmonary , located medial 1/3rd of LLPeak incidence in 2nd and 3rd decade of life

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CT SCANstandard CT examination without contrast material enhancement may be performed Ensure there are no other findings, such as additional nodules lymphadenopathy, pleural effusion, chest wall involvement, or adrenal mass. concerns about radiation dose to the patient, subsequent follow-up CT may be limited to the nodule location.

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CT CONThin-section CT scans obtained through the nodule provide information regarding nodule size (by using diameters from the largest cross-sectional area or volume measurement) attenuation, edge characteristics, and the presence of calcification,cavitation, or fat .Sequential thin-section CT (1 3-mm section width) performed through the entire nodule with a single breath hold and without contrast

GROWTH RATE ASSESMENTAbsence of detectable growth over a 2-year period of is a reliable criterion for establishing that a pulmonary nodule is benignDifficult to detect growth in small (< 1cm) nodules. To overcome this limitation, growth rate of small nodules be assessed using serial volume measurements rather than diameterComputer-aided 3D quantitative volume measurement methods have been developed and applied clinicallyAll these volumetric methods are focused on solid pulmonary nodule

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DOUBLING TIME

Volume is doubled if diameter has increased by at least 1.25 times in at least 2 dimension Usally malignant lesions have a doubling time of 1-6 months. Masses are considered benign when they have not change in size for 18 months

many lesions are not completely sphericalHemorrhage into a lesion can increase the volume dramatically bronchial carcinoids and BAC long doubling times

DYNAMIC HELICAL CTThe lesion should be at least 10mmContrast enhancement is directly related to the vascularity and blood flow Nodule examined 3mm collimation before and after administration of contrast1min interval up to 4min after administration of contrastNodule enhancement= peak mean base line attenuation

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ConEarly cut of point for differention of benign from malignant nodule - 15H enhancementEarly study more focus on early phase of dynamic CT .this studies are more sensitive but less specificOverlap was found between malignant and benign nodules for example,