List 3 common causes of diffuse pulmonary infiltrates in an immunocompromised host?
- Pneumocystis jiroveci
- Drug rxn
List 5 common causes of focal pulmonary infiltrates in immunocompromised hosts
- Gram-negative bacterial infections
- S. aureus
What is the hallmark finding of MAC infections in patients with immunosuppressed (i.e., HIV, elderly, transplant); morphology of the organism?
- Abundant ACID-FAST bacilli within macrophages
- Thin mycobacteria seen as slender red forms
Common sx's of pt with HIV who become infected with MAC?
Fever + drenching night sweats + weight loss
What is the most common opportunistic infection of AIDS patients?
Pneumocystis jiroveci pneumonia
Opportunistic infections are common causes of pneumonia in HIV pt's, but what are 4 of the more common "usual" bacteria that may be seen?
- S. pneumoniae
- S. aureus
- H. influenzae
- Gram-negative rods
As a general rule of thumb which organisms causing infection in HIV pt's are more likely with a CD4 count >200, <200, and <50?
- >200 = bacterial and tubercular infections
- <200 = Pneumocystis pneumonia
- <50 = CMV, fungal, and Mycobacterium avium complex
What is most likely seen on CXR of pt with HIV infected with Pneumocystis jiroveci?
- Diffuse BILATERAL interstitial infiltrates
- Can also be focal or show nothing!
What is the characteristic morphology of the yeast, Pneumocystis jiroveci?
Cup-shaped yeast forms
Which type of organism is the most common cause of pulmonary infection in the early post-transplant period (first few weeks)?
Since acute rejection following a lung transplant has a similar picture to infections, diagnosis relies on what?
What is the morphology of acute rejection of a lung transplant that differentiates it from an infection?
Rejection shows mononuclear infiltates around small vessels, in submucosa of airways, or both
What is the major morphological pattern of damage seen with chronic rejection following a lung transplant?
Bronchiolitis obliterans --> fibrosis causing partial or complete occlusion of small airways WITH or WITHOUT active inflammation
What age is the peak incidence of lung cancer seen?
Large areas of "benign" respiratory mucosa being mutagenized by exposure to carcinogens in tobacco smoke is known as what?
Deletions of which 3 chromosomal loci and 3 genes are seen as early events in the squamous cell carcinoma of the lung
- 3p and 9p (site of CDKN2A gene --> product = p16)
- 17p (site of TP53 gene)
- Loss of RB tumor suppressor
Amplification of which gene has been associated with squamous cell carcinoma of the lung?
Which type of lung cancer shows the strongest association with smoking?
Small cell carcinoma
Loss of function mutations in which 2 genes and chromosome are seen with small cell carcinoma of the lung?
- Chromosome 3p deletions
Amplification of which gene is associated with small cell carcinoma of the lung?
Oncogenic gain of function mutations in which 5 RTK genes are associated with Adenocarcinoma of the lung?
Tumors without RTK mutations often have mutation in which gene?
- RTK mutation = EGFR + ALK + ROS + MET and RET
- Non-RTK = KRAS
Lung cancers in never smokers are more common in which sex and are most often what type of cancer?
Lung cancers in never smokers are more likely to have mutations in which gene and never have mutations in what?
- More likely to have EGFR mutations; sometimes TP53
- NEVER have KRAS mutations
Which type of lung cancer is more commonly arising in the peripheral lung and which in the central/hilar lung?
- Peripheral = adenocarcinoma
- Central/hilar = squamous cell carcinoma
Which precursor lesion is characterized by dysplastic pneumocytes lining alveolar walls that are mildly fibrotic?
Atypical adenomatous hyperplasia
Which precursor lesion is composed entirely of dysplatic cells growing confluently along pre-existing alveolar septae; and may or may not hav intracellular mucin?
Adenocarcinoma in situ
Majority of adenocarcinomas of the lung express which transcription factor required for normal lung development?
Thyroid transcription factor-1
Which tumor of the lung tends to spread aerogenously, forming satellite tumors and may consolidate an entire lobe mimicking lobar pneumonia?
What is the characteristic histologly of squamous cell carcinoma?
Keratin pearls and/or intracellular bridges
Via cytology which color will the cytoplasm be if keratin is present and is indicative of SCC?