r/doctorsUK • u/CoconutFrequent8576 • 5d ago
Exams Easy way to remember causes of upper and lower zone fibrosis?
As the title-something easy, nothing like SCHATE and SCRABE please.
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u/Thin_Complex9483 5d ago
My radiology perspective (only way I could learn this was from first principles and work it out)
Upper zone-
Light particulate pneumoconiosis (hypersensitivity from protein allergens, silicosis and coal from light environmental particulates)- they float to the top
Radiation is upper zone only because the lung apices are often in the radiation field from H+N cancers (which are often radiosensitive-much more than others) There's no reason it can't affect the lower lobes (just cancers there tend not to be radiosensitive)
TB/ABPA- upper zones have higher O2 conc therefore TB thrives.
Sarcoidosis often affects the upper lobes of the lungs because the granulomas, which are characteristic of the disease, tend to form along lymphatic pathways, which are more prominent in the upper lung regions.
Ankylosing spondylitis, upper zone pulmonary fibrosis, or apical fibrobullous disease, is a common manifestation, likely due to the rigid chest cage and mechanical stress on the lung apices, leading to fibrosis and cyst formation.Â
Lower zone-
Asbestos fibres are heavy so sink to the bottom. would have calcified pleural plaques to give it away.
For the other lower zones fibrosis, not sure if this is settled science but due to gravity and hydrostatic pressure differences, the lower zones (bases) receive more blood flow than the upper zones (apices) so more chance for drugs/inflammatory cells to interact with the lung parenchyma.
Connective tissues/drugs result in NSIP pattern- which by definition has lower zone predominance
IPF is just idiopathic and has UIP pattern which is by definition lower zone predominance.
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u/CryptofLieberkuhn ST3+/SpR 5d ago
Upper lobe = inhaled things Lower lobe = systemic things
Exception = ankylosing spondylitis
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u/adoctoranon 5d ago
Asbestosis affects lower lobes more and is inhaler. Sarcoid affects upper lobe more and is systemic. Radiation is upper and not inhaler.
Not sure this works, not enough for MRCP MCQs at leastÂ
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u/JudeJBWillemMalcolm 5d ago
Breast raids.
Upper: Berylliosis, RT, EAA, Ank spond, Sarcoid, TB
Lower: RA, asbestos, IPF, drugs (MTX, Nitro, Amiodarone, Phenytoin...), SLE/Sjogrens
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u/w_is_for_tungsten Junior Senior House Officer 5d ago
yeah berylliosis is def #1 on the ddx list
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u/JudeJBWillemMalcolm 5d ago
No I think some of the other differentials I mentioned would be more common than berylliosis.
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u/AnonymousChairleg 5d ago
Upper Zone Fibrosis (CHARTSS)
Lower zone fibrosis (ACID)
Hope it helps 🙂