Silver-haired teen has recurrent staph abscesses, neuropathy & giant granules in neutrophils. Which defect drives this? A) Lysosome trafficking B) NADPH oxidase C) IL-12 receptor D) CD18 integrin #CoreStepPrep#USMLE#MedStudent#MedSchool#Step1
Ohio spelunker has fever, HSM, pancytopenia; macrophages packed with tiny intracellular yeasts. Key survival trick?
A) Raises phagolysosome pH
B) Urease capsule
C) M protein
D) EF-2 ADP-ribosylation
#CoreStepPrep#USMLE#MedStudent#MedSchool#Step1
19M endurance cyclist: no puberty, tiny testes, eunuchoid habitus + anosmia. Low LH/FSH—what’s the defect? A) GnRH migration B) Sertoli AMH excess C) 5α-reductase loss D) hCG receptor defect #CoreStepPrep#USMLE#MedStudent#MedSchool
Partial albinism + recurrent infections; smear shows giant neutrophil granules. Defective lysosome trafficking uses which motor for minus-end MT transport?
A) Kinesin
B) Dynein
C) Myosin V
D) Clathrin
#CoreStepPrep#USMLE#MedStudent#MedSchool#Step1
Scuba diver with empty sella has cold intolerance + low T4, but TSH isn’t elevated. Which pituitary cell lineage is failing? A) Somatotroph B) Lactotroph C) Thyrotroph D) Corticotroph #CoreStepPrep#USMLE#MedStudent#MedSchool#Step1
New dad with recurrent bronchiectasis, infertility, and dextrocardia has a nasal brush biopsy sent for EM. Which missing ciliary structure explains it?
A) Dynein arms
B) Basal lamina
C) Keratin filaments
D) Desmosomes #CoreStepPrep#USMLE#MedStudent#MedSchool
Traveler w/ chronic diarrhea & arthralgia: duodenal biopsy shows PAS+ macrophages filling villi. What histologic compartment is expanded? A) Lamina propria B) Muscularis mucosae C) Submucosal plexus D) Peyer patches #CoreStepPrep#USMLE#MedStudent#MedSchool
Bike racer numb after saddle trauma: penile bx shows endothelial-lined spaces with smooth muscle trabeculae. What lines the lacunae? A) Simple squamous B) Strat cuboidal C) Pseudostrat columnar D) Transitional #CoreStepPrep#USMLE#MedStudent#MedSchool
Ultramarathoner gets cola urine; dipstick heme+, microscopy no RBCs. Which tubular insult drives AKI? A) Myoglobin cast toxicity B) IgA mesangial deposits C) Anti-GBM antibodies D) ADH excess #CoreStepPrep#USMLE#MedStudent#MedSchool#Step1
Hot-shower acroparesthesias + angiokeratomas in a teen with CKD hint at a lysosomal trafficking jam. Which lipid piles up? A) Sphingomyelin B) GM2 ganglioside C) Globotriaosylceramide D) Heparan sulfate #CoreStepPrep#USMLE#MedStudent#MedSchool#Step1
Winter acrocyanosis + cola urine after atypical pneumonia; DAT shows C3 only. What mediates hemolysis? A) IgM vs I antigen B) IgG vs Rh antigen C) ADAMTS13 inhibitor D) PIGA mutation #CoreStepPrep#USMLE#MedStudent#MedSchool#Step1
After months of amiodarone, a pt develops foamy alveolar macrophages on BAL. Which cell process is drug-impaired? A) Lysosomal phospholipase B) Proteasome ubiquitin C) Peroxisome β-oxidation D) N-linked glycosylation #CoreStepPrep#USMLE#MedStudent#MedSchool
Scuba diver resurfaces with vertigo, L facial paralysis, loss of pain/temp on R body, and ataxia. Which artery is occluded? A) PICA B) AICA C) ASA D) PCA #CoreStepPrep#USMLE#MedStudent#MedSchool#Step1
Drum maker w goat-hair develops fever, dyspnea, widened mediastinum; rods form Medusa-head colonies. Which factor enables toxin entry? A) Poly-D-Glu cap B) Protective antigen C) Edema factor D) Lethal factor #CoreStepPrep#USMLE#MedStudent#MedSchool
NB w/ T21 has nonbilious emesis; x-ray shows double bubble. Pancreatic ring encircles duodenum. Embryologic error?
A) Ventral bud bifurcates
B) Failed gut recanalize
C) Vitelline duct persists
D) NC migration fails
#CoreStepPrep#USMLE#MedStudent#MedSchool
Meconium drains from a newborn’s umbilicus; ileal mucosa lines a patent tract to skin. Which embryonic structure failed to obliterate? A) Vitelline duct B) Allantois C) Urachus D) Omphalomesenteric a. #CoreStepPrep#USMLE#MedStudent#MedSchool#Step1
28F post-liver transplant on tacrolimus feels bugs crawling under skin; MRI normal. Which receptor blockade most likely rapidly quiets this psychosis? A) D2 B) NMDA C) α2 D) 5-HT1A #CoreStepPrep#USMLE#MedStudent#MedSchool#Step1
Teen has epistaxis, menorrhagia, giant platelets, and no ristocetin-induced agglutination. Defect?
A) GPIb adhesion
B) GPIIb/IIIa binding
C) ADAMTS13 loss
D) Factor VIII synthesis #CoreStepPrep#USMLE#MedStudent#MedSchool#Step1