HY USMLE Review Part II PDF

MEHLMANMEDICAL HY USMLE REVIEW PART II  MEHLMANMEDICAL.COM YouTube @mehlmanmedical Instagram @mehlman_medical MEHLMANMEDICAL.COM 2  MEHLMANMEDICAL.COM HY USMLE Review – Part II -...

MEHLMANMEDICAL HY USMLE REVIEW PART II  MEHLMANMEDICAL.COM YouTube @mehlmanmedical Instagram @mehlman_medical MEHLMANMEDICAL.COM 2  MEHLMANMEDICAL.COM HY USMLE Review – Part II - “Hot feels cold; cold feels hot” (temperature dysesthesia) à ciguatera toxicity à toxin blocks sodium channels à caused by consumption of reef fish (mahimahi, Spanish mackerel, etc.) - Pt with no prior Hx of atopy/asthma + eats meaty fish in sketch location (e.g., Bali) + develops dyspnea + allergic-like reaction à answer = scombroid, not seafood allergy à histidine decarboxylase in decaying fish convert histidine to histamine à allergic-like reaction (often misdiagnosed as allergy) - Pt gets allergic-like reaction after eating shellfish à answer = shellfish allergy, not scombroid (students get all trigger-happy about scombroid after learning about something new, weird, and cool, but if on the USMLE they say shellfish, it’s shellfish allergy, not scombroid) - Vomiting a few hours after eating meat à S. aureus preformed heat-stable toxin - Vomiting (or any unusual Sx like bloody diarrhea) + eating custards, creams, potato salad à answer = S. aureus preformed HS toxin à the type of food in this scenario “wins” over the weird bloody diarrhea finding à bear in mind typical bloody-diarrhea-inducing gram (-) rods like EHEC, Yersinia enterocolitica, Campylobacter, Shigella, Salmonella have ~1-3-day incubation period) à iow, if you get sick on the scale of hours from food, S. aureus preformed toxin is likely - Tx of otitis externa à topical ciprofloxacin + hydrocortisone drops - Prophylaxis for otitis externa (i.e., in someone with continued water exposure, like crew) à topical alcohol-acetic acid drops - Tx for cerumen buildup à carbamide peroxide drops - Most common cause of otitis externa à Pseudomonas - Otitis externa + mastoiditis à malignant otitis externa - Mx of malignant otitis externa à CT or MRI of temporal bone because pus collection is common; if don’t rule out fluid collection and drain it appropriately, can cause brain abscess; this is on one of the pediatric NBME forms, where the answer was CT of the temporal bone in a two-year-old, which is an outrageous dose of radiation for a kid, but it’s the answer on the form; in UW for 2CK, they didn’t list CT, but had MRI and x-ray as answers, and MRI was correct; apparently x-ray is insufficient; mastoiditis will classically present in kid with a pinna that’s displaced upward and outward, often with him or her pulling on it bc of the pain. MEHLMANMEDICAL.COM 3  MEHLMANMEDICAL.COM - Tx of otitis media à amoxicillin (amoxicillin/clavulanate [Augmentin] is the wrong answer initially; use Augmentin for recurrent OM) - When to do a tympanostomy tube? à 3+ OM in a 6-month period or 4+ in a year - Tx for Strep pharyngitis? à Amoxicillin or penicillin only (not Augmentin) - Aspiration pneumonia or pulmonary abscess; which antibiotic should be given? à clindamycin (anaerobes above the diaphragm) - Cups and cups of foul-smelling sputum in COPD, TB, or CF patient à bronchiectasis - Most common cause of bronchiectasis à worldwide: TB; in western countries: CF - Young kid + scant white sputum + linear opacity in right-middle lobe on CXR; Dx? à answer = bronchiectasis caused by right middle lobe syndrome (no I am not fucking with you; this is on one of the pediatric 2CK forms à 1st question I’ve ever seen of bronchiectasis where it wasn’t cups and cups of foul-smelling sputum; also, if you Google, it, there literally is a peds condition called right middle lobe syndrome that leads to bronchiectasis à search it over some tacos and a Samuel Adams and knock yourself out) - Chromosome for AR and AD polycystic kidney disease à 6 for AR; 16 for AD - ADPKD à which do we do for screening, MR angiogram circle of Willis, or serial blood pressure checks? à answer = serial blood pressure checks à don’t do MR angiogram screening unless FHx of aneurysm à most patients get high blood pressure from cyst impingement on renal microvasculature à RAAS surges - Most common extra-renal location for cysts à liver - Important point about AR: shows up in peds + causes hepatic fibrosis - Important point about AD: presents in adults; cysts present from birth but just grow + become symptomatic ages 30-40+. - Empiric Abx therapy for meningitis à ceftriaxone + vancomycin (+/- steroids) - Lumbar puncture or Abx first in suspected meningitis? à new guidelines say LP first - When do you do CT head before LP in suspected meningitis? o Confusion that interferes with neurologic exam / decreased GCS score o Seizure o Focal neurologic signs (motor or sensory) MEHLMANMEDICAL.COM 4  MEHLMANMEDICAL.COM o Papilledema or if the optic fundi cannot be visualized o Above reasons indicate potential mass lesion, where if you do an LP you can cause tonsillar herniation and death; if CT negative, proceed cautiously to LP - Bacterial meningitis: low glucose, high protein, high neutrophils (polymorphonuclear cells; PMNs) - Aseptic (viral) meningitis: normal glucose, normal (or slightly elevated) protein, high lymphocytes - Fungal meningitis: low glucose, high protein, high lymphocytes (similar to bacterial, but high lymphocytes instead of neutrophils) - Herpes encephalitis: lots of RBCs in CSF due to temporal lobe hemorrhage à CT is often negative, but sometimes Q will mention wave slowing or temporal complexes on EEG - Difference between meningitis and encephalitis à meningitis is nuchal rigidity (neck stiffness) + photophobia + ophthalmoplegia; encephalitis presents with confusion - Dx of Cryptococcal meningitis? à answer = latex agglutination if it’s listed over India ink; mucicarmine staining (red stain) can also be done - Tx for Cryptococcal meningitis à amphotericin B + flucytosine, followed by fluconazole taper - Nodular density in upper lobe in immunocompromised pt à aspergilloma à next best step = open lung biopsy (sounds radical, but it’s the answer on one of the NBME forms) à Tx with -azole à invasive aspergillosis can be treated with caspofungin or voriconazole - 22M + Hx of three bacterial pneumonias + atopy; presents today with a sore left cheek; Dx? à IgA deficiency (student says “wtf?”) à firstly, sore cheek is sinusitis à IgA deficiency is recurrent sinopulmonary infections that “aren’t that bad” in a patient “not that young” (that is, it’s not a super- sick three-year-old like in SCID or Bruton) à can present with autoimmune phenomena like atopy and vitiligo); also can present with Hx of Giardia à apparently Step 1 is also now testing that IgA deficiency means in the Dx of Celiac disease can’t do IgA anti-tissue transglutaminase reliably bc clearly the pt wouldn’t make the IgA à anaphylaxis after blood transfusion is super HY for IgA deficiency, but also too easy and not mentioned in most Qs. - Most common immunodeficiency in humans à IgA deficiency - 17F + 1-year Hx of autoimmune thyroiditis + 2-year Hx of type I DM + Candidal infections since childhood; Dx? à chronic mucocutaneous candidiasis à two points: 1) clearly the Candidal infections can’t be due to the diabetes if she’s had them since childhood and only DM for two years; 2) USMLE MEHLMANMEDICAL.COM 5  MEHLMANMEDICAL.COM likes “autoimmune conditions go together,” the same way it likes “autoimmune conditions and immunodeficiencies go together”; in other words, CMC and IgA deficiency are examples of immunodeficiencies with an autoimmune origin, so the vignette mentioning autoimmune phenomenon isn’t an accident. - Dx of PJPneumonia à bronchoalveolar lavage - When to add steroids to TMP/SMX for PJP? à A-a gradient >35 or pO2 190 mg/dL o Anyone age 40-75 with an LDL > 70 mg/dL o Age >75 à assessment of risk status + clinician-patient discussion are recommended before commencing or discontinuing a statin o Diabetics