ID
This segmented RNA orthomyxovirus undergoes antigenic shift and drift, leading to both annual epidemics and occasional global pandemics.
What is influenza virus
This benign epidermal tumor appears as a “stuck-on,” waxy, hyperkeratotic papule in older adults and may suddenly erupt in large numbers in the Leser-Trélat sign.
What is Seborrheic keratosis
This cause of acute unilateral vision loss is associated with “curtain coming down” over the visual field, a pale retina with a cherry-red spot, and is an ophthalmologic emergency.
What is Central retinal artery occlusion
This seronegative spondyloarthropathy presents with low back pain that improves with exercise, limited spinal mobility, and bilateral sacroiliitis on imaging, and is strongly associated with HLA-B27.
What is Ankylosing spondylitis
This fracture of the distal radius presents with a “dinner fork” deformity after a fall on an outstretched hand, with dorsal displacement of the distal fragment.
What is Colles fracture
This initial coagulation study tests the intrinsic pathway, normally runs about 25–40 seconds, and is prolonged in factor VIII, IX, XI, and XII deficiencies.
What is aPTT
Which single virulence factor is primarily responsible for the ability of Streptococcus pneumoniae to evade phagocytosis?
What is Polysaccharide capsule
This life-threatening mucocutaneous reaction, most often triggered by medications, presents with widespread epidermal necrosis and detachment involving >30% body surface area.
What is Toxic epidermal necrolysis
This peripheral facial nerve palsy causes inability to close the eye, loss of forehead wrinkling, and drooping of the mouth on the affected side, often following a viral prodrome.
What is Bell palsy
This crystal arthropathy presents with chondrocalcinosis on X-ray and rhomboid, positively birefringent crystals in synovial fluid.
What is Pseudogout
This radiographic pattern in osteomyelitis appears as a segment of necrotic bone separated from viable bone within an area of infection.
What is Sequestrum
This platelet count threshold is where the risk of spontaneous bleeding becomes significant in thrombocytopenia.
What is Platelet count <10,000/µL
A 24-year-old woman has abrupt onset bloody diarrhea, abdominal cramping, and fever after eating undercooked poultry. Stool culture later grows a curved, motile, gram-negative rod. What is the most likely organism?
What is Campylobacter jejuni
This autoimmune blistering disorder features flaccid bullae, erosions, and a positive Nikolsky sign with intraepidermal acantholysis on histology.
What is Pemphigus vulgaris
This chronic inflammatory eyelid condition causes burning, crusting, and scaling at the eyelid margins and is commonly associated with rosacea and seborrheic dermatitis.
What is Blepharitis
This medium-vessel vasculitis is associated with hepatitis B, causes systemic symptoms, livedo reticularis, peripheral neuropathy, and renal involvement without glomerulonephritis.
What is Polyarteritis nodosa
This hip disorder of early childhood presents with a painless limp, limited hip abduction and internal rotation, and idiopathic avascular necrosis of the femoral head on imaging.
What is Legg–Calvé–Perthes disease
This autoimmune platelet disorder presents with isolated thrombocytopenia, enlarged platelets on smear, normal PT/aPTT, and is a diagnosis of exclusion.
What is Immune/Idiopathic thrombocytopenic purpura (ITP)
A 21-year-old man presents with fever, headache, and petechial rash; CSF shows neutrophilic pleocytosis and low glucose. What is the most likely etiologic organism?
What is Neisseria meningitidis
This premalignant lesion occurs on sun-exposed skin as a rough, scaly macule or papule and can progress to squamous cell carcinoma if left untreated.
Actinic keratosis
This benign paroxysmal cause of vertigo is triggered by head position changes and is diagnosed by the Dix-Hallpike maneuver.
What is BPPV
This inflammatory condition of older adults causes proximal muscle pain and stiffness in the shoulder and hip girdles with markedly elevated ESR but normal CK.
What is Polymyalgia rheumatica
This complication of long-bone fracture or orthopedic surgery presents with dyspnea, confusion, and petechial rash on the chest or axilla 24–72 hours after injury.
What is Fat embolism syndrome
This life-threatening microangiopathy presents with thrombocytopenia, hemolytic anemia, neurologic deficits, renal insufficiency, and fever—the classic “pentad.”
What is Thrombotic thrombocytopenic purpura (TTP) / HUS spectrum
A 62-year-old diabetic man on broad-spectrum antibiotics develops profuse watery diarrhea and abdominal pain; labs show leukocytosis, elevated creatinine, and low albumin. Which oral agents are first‑line treatments?
What are oral fidaxomicin or oral vancomycin as first‑line therapy.
This depigmenting disorder presents with well-demarcated, chalk-white macules due to autoimmune destruction of melanocytes.
What is Vitiligo
This inflammatory condition of the lacrimal sac presents with pain, erythema, and swelling over the medial canthus of the lower eyelid, often with purulent material expressible from the punctum.
What is Dacryocystitis
This systemic sclerosis variant presents with limited skin thickening of the face and distal extremities, pulmonary hypertension, and anticentromere antibodies.
What is Limited cutaneous systemic sclerosis (CREST syndrome)
This malignant small round cell bone tumor in children and adolescents commonly arises in the pelvis or diaphysis of long bones and shows an “onion-skin” periosteal reaction on imaging.
What is Ewing sarcoma
This qualitative platelet disorder is due to deficiency or inhibition of von Willebrand factor, often shows mucocutaneous bleeding, abnormal ristocetin test, and may prolong aPTT via factor VIII.
What is von Willebrand disease
A 30-year-old male injection drug user presents with descending symmetric paralysis, diplopia, and fixed, dilated pupils 24 hours after ingesting home-canned food. Which bacterial toxin mechanism explains his symptoms?
What is Blockade of acetylcholine release at the neuromuscular junction
This complication of varicella-zoster virus reactivation causes ipsilateral facial paralysis, otalgia, and painful vesicles in the external auditory canal or pinna, and may lead to hearing loss and vertigo if not promptly treated with antivirals and corticosteroids.
What is Ramsay Hunt syndrome
This posterior pharyngeal infection in young children presents with neck stiffness, torticollis, drooling, muffled voice, and a bulging posterior pharyngeal wall on exam, often secondary to URI or trauma.
What is Retropharyngeal abscess
This inflammatory myopathy presents with symmetric proximal muscle weakness, elevated CK, and endomysial inflammation with CD8+ T cells on muscle biopsy.
What is Polymyositis
This chronic overuse injury in gymnasts and adolescent athletes presents with low back pain, worse with extension, and is due to a defect in the pars interarticularis, best seen on oblique lumbar X-ray.
What is Spondylolysis
This X-linked recessive coagulopathy causes spontaneous hemarthroses, muscle hematomas, and prolonged aPTT with normal PT due to factor VIII deficiency.
What is Hemophilia A
This acid-fast bacillus causes a chronic pulmonary disease with cavitary upper lobe lesions and is detected by sputum smear and culture on Lowenstein-Jensen medium.
What is Mycobacterium tuberculosis
This neonatal exanthema begins on the face and spreads in a cephalocaudal pattern, is caused by a togavirus, and is associated with “blueberry muffin” lesions in congenital infection.
What is Rubella
This otologic emergency follows a blow to the ear, producing fluctuance between the perichondrium and cartilage of the pinna, and can result in a permanent “cauliflower ear” if not promptly aspirated and compressed.
What is Auricular hematoma
This autoantibody pattern is strongly associated with diffuse cutaneous systemic sclerosis and a higher risk of interstitial lung disease.
What is Anti–Scl-70 (anti–topoisomerase I) antibody
This aggressive epiphyseal bone tumor in young adults presents with knee pain and a lytic lesion extending to the subchondral bone, showing a “soap-bubble” appearance and multinucleated giant cells on histology.
What is Giant cell tumor
This consumptive coagulopathy features prolonged PT and aPTT, low platelets, low fibrinogen, elevated D-dimer, and schistocytes, and results from uncontrolled activation of coagulation and fibrinolysis.
What is Disseminated intravascular coagulation (DIC)