Lung Path, Infxn, Resp Symptoms and Bio Flashcards
Which airways have cartilage vs. don’t?
Presence of cartilage differentiates bronchus (present, to maintain patency) from bronchioles (cartilage disappears)
Differentiate bronchus from bronchiole
Bronchus has cartilage to maintain patency, bronchiole defined by lack of cartilage
-bronchiole in bronchovascular bundle same size as adjacent PA branch
Differentiate two types of bronchioles
Bronchioles = airways w/o cartilage (vs. bronchus w/ cartilage)
- membraneous bronchiole = continuous muscular wall, then gives rise to respiratory bronchiole
- respiratory bronchiole = partial muscular with partially alveolated wall
- then respiratory bronchiole gives rise to alveolar duct (completely alveolar wall)
Anatomically define alveoli
Alveoli = blind ending sacs that are the site of gas transfer, alveoli coalesce to form alveolar ducts –> respiratory bronchioles (partially muscular, pratially lined w/ alveoli) –> membranous bronchioles (all muscular not lined w/ alveoli)
Define lobule
Lobule = lung parenchyma sitting between two interlobular septa
-picture showing respiratory brochiole and PA artery branch
Immunohistochemical features differentiating the three most common types of lung CA
Squamous: p40+, TTF-1 negative
Adeno: TTF-1 positive, p40 negative
Small cell: combo: TTF1 positive, CD56/chromogranin, synaptophysin positive (so TTF-1 positive doesn’t differentiate adeno and small cell, need cell morphology)
Pulmonary carcinoid tumors
(a) Typical location
(b) Pathologic findings
(c) Why can’t cure with curetting?
Pulmonary carcinoid- all malignant
(a) Typically endobronchial
(b) Highly vascular, then grade with mitotic figures and degree of necrosis
(c) Have to resect, can’t just curette out, b/c always invade the bronchial wall
Most common etiology of imaging finding
Hamartoma- benign solitary pulmonary nodule with characteristic popcorn calcification
-typically fat, calcification
Most likely which lung cancer given finding of intercellular bridge?
Finding seen in squamous cell carcinoma
- keratinization (squamous pearls) and/or intercellular bridges
- p40 positive, TTF-1 negative
Histologic features (not stains) that differentiate squamous cell carcinoma from adenocarcinoma
Squamous cell- keratinized cells, intercellular bridges
AdenoCA- makes glands or secretes PAS+ mucin

What is lepidic growth?
(a) Characteristic of what malignancy?
Lepidic growth = growing along alveolar walls
(a) Adenocarcinoma in situ (AIS, new name for BAC) start with lepidic growth (thickened-appearing alveoli with atypical cells). AIC grows in uniform manner along alveolar walls w/o evidence of invasion

Histologically differentiate minimally invasive adenoCA from lepidic predominant adenoCA
Both have background of peripheral lepidic growth, then different size of invasive part
- minimally invasive aenoCA: lepidic growth background with under 5mm invasive part
- lepidic-predominant adenoCA: lepidic growth background with invasion over 5mm

Why clinically relevant to see if lepidic growth has any areas of invasion?
If no invasion then adenocarcinoma in situ (AIS, formerly called BAC) is 100% curable with local wedge resection
- pure lepidic growth = AIS
- once have any area of invasion: if under 5mm = minimally invasive adenoCA, if over 5mm = lepidic predominant adenoCA
Which lung nodule is more concerning?

Left = pure GGO- presume adenocarcinoma in situ (AIS, BAC) or minimally invasive adenoCA (invasive component under 5mm) = better prognosis
vs.
Larger the solid component = higher risk of invasion, if over 50% solid or growing solid component higher concern for lepidic predominant adenoCA
How is adenocarcinoma characterized?
(a) Why clinically relevant
Not characterized by well or poorly differentiated, instead based on histologic subtype
- High grade = solid and micropapillary
- Intermediate grade = acinar and papillary
(a) Relevant b/c high grade (solid and micropapillary) have worse prognosis than intermediate (acinar and papillary)

Differentiate WHO 2015 classification of squamous cell and adenocarcinoma
WHO 2015 classification
- squamous cell = keratinizing (cells that make keratin) or p40 positive
- adenocarcinoma = diffusely TTF-1 positive whether they make glands or contain mucin (b/c not all do, cann be poorly differentiated and just have the stain)
What is the most likely lung malignancy given this histology?

Small cell- 2-3 x number of lymphocytes (small cells), then very blue b/c high nuclear (blue) to cytoplasmic ratio

Defining features of large cell carcinoma
- large cells (specifically large nucleoli) notably WITHOUT features of squamous (keratinic, intercellular bridges) or adenocarcinoma/glandular (mucinous, papillary) differentiation
- negative p40 (squamous) and TTF-1 (adenoCA)
Why important clinically to separate adenoCA and squamous cell CA
Yes both are NSCLC so have the same staging and similar treatment algorithms
-but adenoCA more likely to have EGFR, VEGF, ALK/ROS mutations while squamous do not => immunotherapy
How to histologically define the size of adenocarcinoma vs. adenocarincoma in situ
Adenocarcinoma tumor size counted by the INVASIVE portion of the lesion, not the entire lesion
-can have lepidic growth but the tumor size is based on the invasive portion

How are pulmonary carcinoid tumors classified?

Two types
- typical: less than 2 mitosis per 10 high power fields, absence of necrosis
- atypical (worse prognosis): 2 or more mitosis per 10 HPFs or presence of necrosis
Pulmonary carcinoid tumors
(a) Typical clinical features
(b) Smokers or nonsmokers
Carcinoid
(a) 70% are in proximal airways => cause airway symptoms like cough, hemoptysis, bronchial obstruction
(b) Typically in never smokers
2 malignancies with clasically false negative PET
- Adenocarcinoma in situ- ground glass nodule on imaging, low PET uptake
- pulmonary carcinoid tumors- typically in proximal airways
Differentiate management of pulmonary carcinoid tumors from other NSCLC
Pulmonary carcinoid- no proven benefit of chemo or radiation even for metastatic disease => just surgery and LN dissection even in most extensive form
- typical carcinoid (low mitoses, no necrosis): limited resection with segementectomy and regional LN dissection
- atypical sarcoid (more than 2 mitoses per 10 HPF or presence of necrosis): lobectomy and mediastinal LN dissection





























































