Pulmonary infection Flashcards
Clinical classifications of pneumonia (5)
CAP, HAP, HCAP, VAP, Pneumonia in immunocompromised patient.
Communiy acquired pneumonia pathogens
- Most common
- Atypical pneumonia pathogens
- Elderly smokers
- Alcoholics and aspirators
- S. pneumonia
- mycoplasma, viral, chlamydia
- legionella (peripheral consolidations, progresses to lobar and multilobar)
- Klebsiella. Voluminous inflammaory exudates causing bulging fissure sign.
HAP and HCAP. Disctinction and pathogens
HAP in hospitalized patients. HCAP in patients in nursing homes or prior hospitalization.
Pathogens: MRSA, pseudomonas.
Opportunistic pathogens (4)
PCP, Aspergillus, nocardia, CMV.
radiographic patterns of infection (4)
Lobar
Lobular (bronchopneumonia) - patchy consolidation
Interstitial pneumonia (mycoplasma, chlamydia, pneumocystis)
Round pneumonia
Round pneumonia: most common pathogen. Why is infection confined?
Strep pneumo
Infection confined due to incomplete formation of pores of Kohn
Complications of pneumonia (6)
Pulmonary abscess, pulmonary gangrene, Empyema, Pneumatocele, Bronchopleural fistula, Empyema necessitans.
3 stages of empyema
Free flowing exudative effusion.
Development of fibrous strands
Fluid becomes solid and jelly like.
Bronchopleural fistula
What is it? Causes?
Can occur from rupture of visceral pleura as complication of pneumonia. But most common cause is Surgery. Other etiologies include lung abscess, empyema, and trauma.
Empyema necessitans. What is it, what are most common pathogens
Extension of empyema into chest wall. Most commonly due to TB, but also seen in Nocardia and actinomyces.
3 clinical scenarios of TB
1-2. Initial exposure to TB can lead to 2 clinical outcomes
- re-activation
- Contained disease (90%). (primary)
- Primary progressive TB (host cannot hold disease. Occurs in children and immunocompromised)
- re-activation
Primary TB. (Can be normal on CXR)
1, What are the 4 imaging manifestations
- 2 Classic imaging complexes
- Ill-defined consolidation, pleural effusion, lymphadenopathy, milliary disease.
- a. Ghon focus - parenchymal infection - calcified granuloma
b. Ranke complex - Ghon focus + lymphadenopathy.
In TB, when do you see cavitation, when do you see adenopathy?
Cavitation is seen more commonly in reactivation TB.
Adenopathy is more common in primary TB.
- Most common location for primary TB
- Most common location of reactivation TB
- Primary: RML, RLL
- reactivation - upper lobe apical and posterior segments.
Imaging of re-activation TB in immunocompetent patient and immunosuppressed patient.
Immunocompetent patient: cavitation, lack of adenopathy. Endobronchial spread (Tree-in-bud)
Immunocompromised: low attenuation adenopathy may be seen.
Signs of healed TB
Apical scarring, usually upper lobes. Superior hilar retraction.
Calcified granulomas may be a sign of containment of initial infection by delayed hypersensitivity response
What is strongest risk factor for TB progression?
Other less serious risk factors
HIV
Malnutrition, drugs/alcohol, silicosis
What is the name of Pulmonary artery aneurysm in TB (mycotic aneurysm in TB)
Rasmussen aneurysm
AT what CD4 count do you have reactivation TB
At what CD4 do you have primary progressive TB
- CD4>200
- CD4<200
Atypical mycobacteria infection
- Classic presentation in old lady
- classic cavitary type, seen in old smoker/COPD patient.
- Hypersensitivity reaction to atypical mycobacteria
- Lady Windermere syndrome: Elderly woman, cough, low grade fever, weight loss. bronchiectasis, tree-in-bud, RML or linguila
- Cavitary lesion in upper lobe w/ adjacent nodules.
- Hot-tub lung: HSP in response to atypical mycobacteria in hot tubs. Centrilobular nodules.
Endemic fungi infections
- Histoplasmosis: soil contaminated w/ bat or bird quano.
- what are radiologic manifestionas.
- what is a rare complication. - Coccidiodes
- blastomyces
- calcified granuloma. Less commonly can be a pulmonary nodule: histioplasmoma. Chronic infection can mimic TB
- rare complication is fibrosing mediastinities. infection of mediastinal lymph nodes leading to pulm venous obstruction, bronchial stenosis, and pulm artery stenosis. - found in Southwest US. lots of radiographic appearances, like multifocal conslidation, multiple nodules, miliary nodules.
- central and SE U.S. Usually asymptomatic, but may have flu-like illness that progresses to multifocal consolidation, ARDS, or miliary disease.
PCP - radiographic findings
CXR: Bilateral Perihilar central opacities.
CT - peri-hilar ground glass with come upper lobe pneumatoceles.
Cryptococcus neoformans - most common fungal infection in AIDS patients.
- What is usual CD4
- radiographic appearance
- CD4<100
- can have many radiographic findings, including GGO, focal consolidation, cavitating nodules, miliary disease
Spectrum of pulmonary aspergillus (5)
- asthma
- Pre-existing cavity, sarcoid
- debiliated, diabetic, alcoholic
4-5. neutropenic or immunocompromised
- Allergic bronchopulmonary aspergilosis - finger in glove sign - mucoid impactin of bronchiectasis
- Apergilloma/mycetoma - Monod sign
- Semi-invasive (chronic necrotizing) - chronic consolidation cavitation
- airway invasive - bronchopneumonia centrilobular nodules, tree-in-bud nodules
- Angioinvasive - Halo sign: acute infection (peripheral GGO), air crescent sign: resolving
Allergic bronchopulmonary aspergillosis (ABPA) - hypersensitivty reaction to aspergillus in a person w/ asthma. Presents w/ recurrent wheezing, low grade fever, cough, sputum.
- key CT finding. What can this also be seen in?
Upper lobe bronchiectasis and mucoid impaction - finger in glove sign
Finger in glove sign can also seen in segmental bronchial atresia and CF.
Saphrophytic aspergillosis (aspergilloma) - conglomeration of intertwined aspergillus fungal hyphae/cellular debris (fungus ball) in a pre-existing cavity. Apergilloma is mobile.
- Most common causes for pre-existing cavity
- most common symptom
- main sign
- TB, sarcoid
- hemoptysis
- Monod sign
Semi-invasive aspergillosis (chronic necrotizing)
- Seen in who?
- Symptoms
- CT findings
- debilitate, diabetic, alcoholic, COPD
- cough, fever, hemoptysis
- consolidation cavitation, pleural thickening
Airway-invasive aspergillosis - infection of airway epithelial cells. can range from bronchiolitis to bronchopneumonia
- seen in who?
- CT findings
- Immunocompromised, neutropenic, AIDS patients.
- Centrilobular and tree in bud. bronchopneumonia.
Angioinvasive aspergillosis - aggressive infection - invasion and occlusion of arteriorles
- Seen in who?
- Classic CT signs
- severly immunocompromised
- -CT Halo sign - Central consolidation w/ surrounding GGO
- Air crescent sign - retraction of infarcted lung, good prognostic sign.
What is the reason you get Halo sign in aspergilloma
Hemorrhage
Air and fluin in the pleural space is diagnostic for what?
Bronchopleural fistula
