need help with your account or subscription? click here to email us (or see the contact page)
join telegramNEW! discord
jump to exam page:
search for anything ⋅ score predictor (โ€œpredict me!โ€)
NBME Free 120 Answers

free120/Block 2/Question#33 (reveal difficulty score)
A 17-year-old girl has never had a menstrual ...
Androgen insensitivity ๐Ÿ” / ๐Ÿ“บ / ๐ŸŒณ / ๐Ÿ“–

 Login (or register) to see more

 +9  upvote downvote
submitted by โˆ—bwdc(697)

Androgen insensitivity is caused by a defective androgen receptor. DHT is responsible for creating male genitalia during fetal sexual development. The default human gender is female. So a genetically male patient with complete androgen insensitivity is externally phenotypically female. Lack of response to adrenal androgens prevents hair formation during puberty (adrenarche).

 Login (or register) to see more

 +8  upvote downvote
submitted by โˆ—waterloo(126)

Just to add to explanation. Answer is not congenital adrenal hyperplasia, because pt has normal breast development and normal external genitalia. most common type 21-hydroxylase def would have precocious puberty or clitoral enlargement. Questions says patient has normal appearing external genitalia. 17a-hydroxylase def would lead to ambiguous genitalia in XY and in XX there would be no secondary sexual development because lack of sex steroids. But again, question says pt has normal breast development and external genitalia. In 11B-hydroxylase def, XX would have virilization, again not applicable here.

ectodermal dysplasia would have more characteristics like abnormal teeth, other abnormal findings from ectodermal layer.

a psych disorder could throw you off, maybe patient is not eating enough and is not having a period. But they said normal female body habitus, so I think that seems less likely compared to androgen insensitivity.

Sex chromosome mosaicism made me think of Turner Syndrome. There is a unique body habitus for Turner Syndrome so makes this a wrong answer.

 Login (or register) to see more

 +0  upvote downvote
submitted by myriad(2)

Just wondering, could this patient's presentation also be the result of an Imperforate Hymen or Transverse Vaginal Septum? I was looking for those in the answer choices, and thought Ectodermal Dysplasia might be referring to either of those.

 Login (or register) to see more
zolotar4  so was curious, found on wiki - "If untreated or unrecognized before puberty, an imperforate hymen can lead to peritonitis or endometriosis due to retrograde bleeding." - our patient has no symptoms besides never having a menstrual period and probably would've been seen in the clinical presentation. +1
jj375  Also I think that if it was imperforate hymen or Transverse Vaginal Septum then the patient would have normal axillary and pubic hair. But the lack of these things made me think it was more hormonal +1

Must-See Comments from free120

sugaplum on It is a polymorphism
bwdc on Elaboration of proteases and urease with ...
bwdc on Hypercoagulability from advanced malignancy
bwdc on Ribosomal assembly
bwdc on Aspiration
bwdc on Amygdala
imnotarobotbut on von Willebrand disease
bwdc on Trinucleotide repeat expansion
bwdc on Mediation of cell entry via a fusion protein
bwdc on Metabolism
bwdc on Basement membrane
melchior on Aspiration
hungrybox on Immune complex deposition in tissues
aejinkim on Decreased activity in the enzyme that ...

search for anything NEW!