Pulmonology Infection Flashcards
Lobar PNA
Consolidation of entire lobe of the lung – usually bacteria (strep pneumoniae, Klebsiella pneumoniae)
Strep pneumoniae
Most common cause of community-acquired PNA & secondary PNA
Klebsiella pneumoniae
Malnourished and debilitated individuals – elderly in nursing homes, alcoholics and diabetics
+Thick mucoid capsule
+ currant jelly sputum
Complicated by abscess
Bronchopneumonia
Scattered patchy consolidation centered around bronchioles – multifocal and bilateral – usually bacteria
Bronchopneumonia common causes
Staph aureus
Haemophilus influenzae
Pseudomonas aeruginosa
Moraxella catarrhalis
Legionella pneumophila
Staph aureus
2nd common cause of secondary PNA, oft complicated by abscess or empyema
Haemophilus influenzae
Common cause of 2nday PNA and COPD PNA
Pseudomonas aeruginosa
PNA CF pts
Moraxella catarrhalis
Community-acquired PNA and PNA superimposed of COPD
Legionella pneumophila
Community-acquired PNA, PNA on COPD, PNA in immunocompromised – transmitted by water – best visualized by silver stain
Interstitial: diffuse interstitial infiltrates – mild upper respiratory sx, atypical
Interstitial PNA (atypical)
Diffuse interstitial infiltrates – mild upper respiratory sx, atypical presentation – usually bacteria or viruses
Mycoplasma pna:
Chlamydia pna
Respiratory syncytial virus (RSV)
Cytomegalovirus (CMV)
Influenza virus
Coxiella burnetii
Mycoplasma pna
Most common cause of interstitial pna – crowded spaces base/dorms (young adults) – complication –> autoimmune hemolytic anemia (IgM against I antigen on RBC) and erythema multiforme
Chlamydia pna
Second most common cause of atypical PNA
Respiratory syncytial virus (RSV)
Most common cause of atypical PNA in infants
Cytomegalovirus (CMV)
Common in posttransplant immunosuppression or chemotherapy
Influenza virus
Atypical PNA in elderly, immunocompromised with preexisting lung disease. Increased risk for superimposed S. aureus or H. influenzae bacterial PNA
Coxiella burnetii
Atypical PNA w/ high fever (Q fever), common in farmers and vets (cattle via ticks) – No skin rash unlike other rickettsiae
Alpha 1 - Antitrypsin (A1AT) deficiency
Lack anti-protease leaving air sacs vulnerable to protease mediated damage
+Panacinar emphysema
Liver cirrhosis also may present – hepatocytes + A1AT accumulation (PAS-positive)
Small cell carcinoma
Poorly differentiated small cells with neuroendocrine differentiation chromogranin positive
Located centrally
Male smokers
Rapid growth and early mets
Paraneoplastic syndrome
Adenocarcinoma
Glands, mucin, TTF-1 expression by immunohistochemistry
Peripheral location
Adenocarcinoma in-situ exhibit columnar cells that grow along preexisting bronchioles and alveoli – may look like pneumonia like consolidation on imaging
Squamous cell carcinoma
Keratin pearls, intracellular bridges or p40 expression by IHC
Centrally located
May produce PTHrP
Large cell neuroendocrine carcinoma
Poorly differentiated large cells (no glands, mucin, TTF-1, keratin pearls, intracellular bridges or p40)
Dx of exclusion
Carcinoid tumor
Well differentiated neuroendocrine cells (nests); chromogranin positive
Not sig related to smoking
Central location forms a polyp-like mass in the bronchus, can be peripheral
Low-grade malignancy, rarely, can cause carcinoid syndrome
Metastasis to lung
Most common sources are breast and colon carcinoma
Multiple cannon-ball nodules on imaging
More common than primary tumors
