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NBME 20 Answers

nbme20/Block 4/Question#21

A 47-year-old woman comes to the physician because ...

Contact with parakeets

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FA 2019 P. 661 Hypersensitivity Pneumonitis is a mixed type III/IV hypersensitivity reaction to an antigen in the environment. Commonly seen in farmers and people exposed to birds. Presents with Dyspnea, Cough, Chest tightness, headache. It is reversible in the early stages if the allergen is removed.

+/- lilyo(4),


 +5  upvote downvote
submitted by hayayah(447),

Hypersensitivity pneumonitis—mixed type III/IV hypersensitivity reaction to environmental antigen. Causes dyspnea, cough, chest tightness, headache. Often seen in farmers and those exposed to birds. Reversible in early stages if stimulus is avoided.

It's a type of restrictive lung disease.



A type of hypersensitivity pneumonitis associated with animal exposure is bird fancier’s lung, in which the major antigens are proteins in avian serum, feces, and feathers, including bloom, the waxy powder coating them (18). Pigeons and parakeets, including budgerigars (a type of parakeet), are the birds most commonly implicated, but poultry, finches, doves, canaries, and other birds also have caused the disease. Exposure to live birds is not necessary to produce hypersensitivity pneumonitis: the illness has resulted from using feather pillows and duvets (19), being exposed to a wreath made from the feathers of a dead pet bird (20), and laundering a pigeon keeper’s overalls (21). Other examples of animal proteins that are known to have caused the disease when inhaled include proteins from the dust of mollusk shells used to make buttons (22) and from animal fur used in garment manufacture

https://pubs.rsna.org/doi/full/10.1148/rg.297095707

+/- alexp1101(0),


 +3  upvote downvote
submitted by monoloco(64),

This patient is experiencing hypersensitivity pneumonitis from the parakeets. I was thinking M. Avium when I selected parakeets -- I think my logic was flawed given the specifics of the patient's story.





 +1  upvote downvote
submitted by breis(14),

Psittacosis (sometimes called ornithosis or parrot disease or parrot fever) is an infection of the lung (pneumonia) caused by the bacterium Chlamydophila (Chlamydia) psittaci.

Signs and symptoms: fever. cough, usually without much phlegm. headache. rash. muscle aches. chest pain. shortness of breath. sore throat.

charcot_bouchard  Update on my prev comment : Yes this is psittacosis. not hypersensitivity pneumonitis. How do u know? Lymphocyte and Presence of Granuloma - response to intracellular chlamydia. Now HS can also cause loose granuloma too and the clinical picture still more look like HS You know what ......... fuck this ques +  
shemle  Here Pt. doesn't have fever! +  




 +0  upvote downvote
submitted by imnotarobotbut(39),

How would you know that it isn't wool sorters disease?

cienfuegos  FA 2018 137: inhalation of spores leads to flu-like symptoms that progress quickly to fever, pulmonary hemorrhage, mediastinitis and shock, with imaging possibly showing widened mediastinum +  




 +0  upvote downvote
submitted by beeip(65),

I also was thinking M. avium here, but hypersensitivity pneumonitis seems to fit with the reticulogranular changes.





 +0  upvote downvote
submitted by endochondral1(5),

how do we know parakeets cause hypersensitivy pneumonitis

smc213  FA18 p.657 bird exposure--> HSN pneumonitis (restrictive lung disease) and FA18 p.214 granulomatous diseases: foreign material-->HSN pneumonitis. I had to make sense of it since I didn't know it was HSN pneumonitis at first. +  




 +0  upvote downvote
submitted by endochondral1(5),

according to uworld hypersensitivity pneumonitis is due to dust and that was also an option....

amarousis  so it's definitely dust but the specific type of dust was the most important in this question. the fact that they mentioned the birds is important. the dusty books would cause it but the bird dust is more important -.- +  
charcot_bouchard  Hypersensitivity Pneumonitis - Organic dust (like moldy hay) Pneumocniosis - Inorganic dust none help here though because both will present with same restrictive lung disease picture. i think since dust in library arent neither organic or inorganic and also u dont see many librarians with lung disease but bird ownership is specifically mentioned as cause of HP disease. +  




one does not simply “walk into morder”