Uworld13 Flashcards
Function of aromatase and its deficiency
Aromatase is responsible for converting androgens into estrogens.
Deficiency of this enzyme causes accumulation of androgens during pregnancy, resulting in ambiguous external genitalia in newborn females and maternal gestational virilization
What is stranger anxiety?
Stranger anxiety, which presents as crying or screaming when unfamiliar people approach, is a normal and expected part of childhood development.
It typically begins around 6 months and resolves by 2 years.
What is thyroid hormone resistance?
Decreased sensitivity of peripheral tissues to thyroid hormones due to a defect in the thyroid hormone receptor.
Levels of thyroxine, triiodothyronine, and TSH are increased.
Patients classically have goiter and frequently develop attention deficit hyperactivity disorder.
What is lateral epicondylitis (tennis elbow)?
Overuse of wrist extensor muscles (extensor carpi radialis, extensor digitorum) leading to angiofibroblastic tendinitis at their attachment on the lateral epicondyle
Unlike Plasmodium falciparum, the eradication of Plasmodium vivax and Plasmodium ovale requires?
Requires primaquine to target the dormant hepatic phase.
Patients not receiving treatment that targets the hepatic phase will likely develop relapsed symptoms weeks or months later.
The work of breathing is minimized in patients with?
Increased elastic resistance (eg pulmonary fibrosis) when their respiratory rate is high and tidal volume is low (fast, shallow breaths)
What is the work of breathing in patients with diseases that increase airflow resistance (eg, asthma, chronic obstructive pulmonary disease)?
Breathe at a lower respiratory rate and higher tidal volume (slow, deep breathes) to minimize the work of breathing.
Treatment for bulimia nervosa?
Nutritional rehabilitation, cognitive-behavioral therapy, and pharmacotherapy with selective serotonin reuptake inhibitors. Fluoxetine is drug of choice.
What is ataxia-telangiectasia?
AR; results from a defect in DNA-repair genes.
The DNA of these patients is hypersensitive to ionizing radiation.
Manifestations include cerebellar ataxia, oculocutaneous telangiectasias, repeated sinopulmonary infections, and an increased incidence of malignancy.
What is the function of neprilysin?
Neprolysin is responsible for the breakdown of the natriuretic peptides and angiotensin II; therefore, inhibition of neprilysin increases the activity of these peptides.
For treatment of heart failure, neprilysin inhibition is combined with angiotensin II receptor blockade to optimize the positive effects of the natriuretic peptides (vasodilation, diuresis) while blocking the negative effects of angiotensin II (eg vasocontriction, fluid retention)
Pelvic fracture are frequently associated with injury to?
The posterior urethra, in particular the bulbomembranous junction.
Inability to void despite a full bladder sensation, a high riding boddy prostate, and blood at the urethral meatus are clinical findings suggestive of urethral injury.
How do penicillins and cephalosporins function?
By irreversibly binding to penicillin-binding proteins such as transpeptidases.
A change in the structure of penicillin-binding proteins that prevents cephalosporin binding is one mechanism of bacterial resistance to cephalosporins.
What are the potassium levels in diabetic ketoacidosis?
Most patients with diabetic ketoacidosis have normal to increased serum potassium levels despite a total body potassium deficit.
Replacement of potassium is a crucial step in the management of patients with diabetic ketoacidosis.
MOA of letrozole
Polycystic ovary syndrome can present with irregular menses, enlarged ovaries, and anovulatory infertility.
Letrozole, an aromatase inhibitor, acts on the ovary and peripheral adipose tissue to inhibit androgen-to-estrogen conversion by the enzyme aromatase; the subsequent decrease in estrogen production causes the pituitary to release more FSH and LH, thereby stimulating ovulation
Where do potassium sparing diuretics (spironolactone, amiloride) act on the nephron?
Act on the late distal tubule and cortical collecting duct to antagonize the effects of aldosterone
All diuretics except the potassium sparing class cause potassium loss by increasing sodium delivery to the late distal tubule and cortical collecting duct, where aldosterone-induced sodium reabsorption occurs at the expense of potassium.
What is the path of the phosphoinositol second messenger system?
The phosphoinositol second messenger system begins with ligand-receptor binding and Gq protein activation leading to activation of phospholipase C (PLC).
PLC then hydrolyzes phosphatidyl inositol bisphosphate and forms diacylglycerol and inositol triphosphate (IP3)
Finally, IP3 activated protein kinase C via an increase in intracellular Ca2+
Central nervous system lesions cause what to the face?
Because the upper face receives bilateral input from the motor cortices, central nervous system lesions typically cause lower facial weakness that spares the forehead on one side of the fact.
Peripheral lesions (Bell palsy) cause what to the face?
cause weakness of the entire side of the face. Bell palsy may also result in decreased tear production, hyperacusis, and reduced taste sensation.
How can SNRI be used for neuropathic pain?
Serotonin-norepinephrine reuptake inhibitors are often used for neuropathic pain. They increase norepinephrine in the central synapses, which modulates the descending pain pathway, leading to decreased central perception of pain.
What is primary ciliary dyskinesia?
results from an autosomal recessive mutation in the proteins responsible for normal flagellar and ciliary structure and function (eg, dynein, assembly proteins)
CF: situs inversus, chronic sinusitis, bronchiectasis, and infertility.
What is the most life threatening complication associated with Marfan syndrome?
Cardiovascular lesions.
Early onset cystic medial degeneration of the aorta predisposes to aortic dissection, the most common cause of death in these patients.
When should Turner syndrome be suspected?
Turner syndrome (loss of an X chromosome) should be suspected in a newborn girl with cystic hygroma or lymphedema.
Dysmorphic features (high arched palate, low set ears) and aortic anomalies (coarctation) are some findings.
What is a harmartoma?
Hamartomas are common, slow growing, benign lung neoplasms microscopically characterized by nodules of disorganized, mature connective tissue (cartilage, fat) and entrapped respiratory epithelium. They are often detected incidentally by imaging, appearing as well circumscribed, peripheral, solitary lung lesions.
Lymph from the testes drains?
Through lymph channels directly back to the para-aortic lymph nodes
Lymph from the scrotum drains?
to the superficial inguinal lymph nodes.
Selective estrogen receptor modulators (tamoxifen, raloxifene) MOA
Selective estrogen receptor modulators exhibit estrogen antagonist and agonist properties in a tissue specific manner.
Raloxifene has estrogen agonist activity on bone, which decreases bone resorption and improves bone density. It has an estrogen antagonist effect on breast tissue, decreasing the risk for break cancer; it also acts as an estrogen antagonist in the uterus and does not increase the risk for endometrial cancer.
Tamoxifen acts as an estrogen agonist in the uterus and increases the risk for endometrial hyperplasia and cancer.
How many calories is in protein/carbs and fat?
metabolism of 1 g of protein/carb = 4 calories of energy
metabolism of 1 g fat = 9 calories
MOA of benzodiazepines?
Act by binding to the benzodiazepine binding site, which allosterically modulates the binding of GABA, resulting in an increased frequency of chloride ion channel opening.
The influx of chloride ions into the neurons causes neuronal hyperpolarization and inhibition of the action potential.
What is dissociative amnesia?
An isolated inability to recall important autobiographical information that is inconsistent with ordinary forgetfulness. It typically occurs abruptly following an overwhelming, traumatic event.
Flexor digitorum profundus tendon insertion and function
Inserts onto the base of the distal phalanx and flexes the distal interphalangeal (DIP) joint.
It is susceptible to rupture when an actively flexed DIP joint is forcefully hyperextended
What is factor V Leiden mutatuon?
Inherited causes of hypercoagulability should be considered in patients younger than 50 who present with thrombosis and no obvious explanation for an acquired prothrombotic state.
The factor V Leiden mutation, which causes factor Va resistance to inactivation by activated protein C, may account for approximately 20% of cases of atypical venous thrombosis.
Treatment for enterobius vermicularis infection (enterobiasis)
enterobius vermicularis infection (enterobiasis) occurs most frequently in children and presents with perianal pruritus.
Diagnosis is made by indentifying eggs in the perianal region (cellulose tape test).
Treatment: albendazole, mebendaozle, and pyrantel pamoate.
What is anemia of chronic disease?
Is a consequence of chronically elevated inflammatory cytokines, most important hepcidin.
This peptide inactivates iron channels on enterocytes and reticuloendothelial macrophages, leading to reduced iron absorption and reduced iron release from the reticuloendothelial system.
The net result is normocytic or slightly microcytic anemia with low reticulocyte response, low serum iron level, or normal or low total iron binding capacity.
A stoke in the lateral brainstem can lead to?
Ipsilateral Horner syndrome because sympathetic neurons travel next to the spinothalamnic tract in the lateral medulla.
What is the cause of Down syndrome?
CF: cognitive impairment, facial dysmorphism, and cardiac defects
95% of cases are caused by the presence of an extra chromosome 21 (trisomy) resulting from nondisjunction.
Unbalanced Robertsonian translocations or mosaicism are less common causes.
Lepromin skin test results for patients in leprosy
The lepromin skin test will be positive in patients with tuberculoid leprosy as they exhibit a strong CD4+ Th1 cell mediated immune response to Mycobacterium leprae.
Patients with lepromatous leprosy will test negative due to their weak Th1 cell mediated immune response
Signs of vitamin A toxicity?
benign intracranial hypertension (headache, vomitting, papilledema), dry skin, and hepatomegaly.
Risk factors: excessive dietary intake (egg, liver, kidney) or retinoid containing meds
What is Trousseau syndrome? (migratory superficial thrombophlebitis)
A paraneoplastic syndrome of hypercoagulability may be seen in some patients with cancer, especially adenocarcinomas of the pancreas, colon or lung.
Superficial venous thromboses may therefore appear in one site and then resolve, only to recur in another site. This is known as Trousseau syndrome, an indication of visceral cancer.
What is gonadal dysgensis (streak ovaries)
Most commonly caused by Turner syndrome and results in primary ovarian insufficiency (amenorrhea, infertility)
Patients are at increased risk for aortic dissection and horseshow kidney
Anti-Rh immunoglobulin consists of?
anti-D IgG antibodies that bind to Rh-positive fetal erythrocytes, promoting clearnace by maternal reticuloendothelial macrophages and preventing maternal Rh sensitization.
It is routinely adnmistered to Rh-negative women during gestation and immediately postpartum
What is acute intermittent porphyria?
Due to the accumulation of aminolevulinate (ALA) and porphobilinogen (PBG) resulting from inherited PBG deaminase deficiency combined with ALA synthase induction (typically due to certain meds, alcohol, or a low calorie diet)
Management with glucose or hemin inhibits ALA synthase activity.
The spleen is derived from?
The spleen is a large, wedge shaped lymphatic organ in the left posterosuperior aspect of the abdominal cavity.
The spleen is derived from the mesoderm in the dorsal mesentery (others include bone, muscle, and kidney)
What happens at high altitude to the respiratory system?
At high altitude, the low partial pressure of inspired oxygen (PiO2) leads to hypoxemia with consequent hyperventilation and respiratory alkalosis.
The hypoxemia and alkalemia can cause symptoms of altitude sickness (headache, fatigue, lightheadedness)
The kidneys respond by creating a compensatory metabolic acidosis and by increasing erythropoietin secretion.
Infarcts involving the anterior portion of the medial pons can produce?
Dysarthria and contralateral hemiparesis/lower facial palsy due to disruption of the ipsilateral corticospinal and corticobulbar tracts.
The trigeminal nerve arises at the level of the middle cerebellar peduncle at the lateral aspect of the mid-pons
What causes cutaneous warts?
HPV, and typically present as skin color papules with a dry, whitish surface.
HPV is transmitted by direct contact
What structure is affected in Parkinson disease?
The majority of substantia nigra dopaminergic neurons (>60%) are lost prior to the onset of motor symptoms in idiopathic Parkinson disease.
During this prodromal period, dopamine depletion is offset by several compensatory mechanisms, including the upregulation of postsynaptic dopamine receptors.
Infection with parvovirus B19 can cause?
parvovirus B19 is a nonenveloped ssDNA virus.
Can cause arthralgia with or without rash in adults.
An infected fetus may develop hydros fetalis (severe anemia, heart failure, pleural effusions, pericardial effusions, and ascites)
Positive staining for cytokeratin in tumor cells suggests?
Cytokeratins are a type of intermediate filaments protein found in epithelial cells.
Positive staining suggest a tumor has epithelial origin (carcinomas)
What is required for Haemophilus influenzae to grow?
It is a blood loving organism that requires X (hematin) and V (NAD+) factors for growth.
This can be accomplished by growing H influenza in the presence of Staph aureus and demonstrating the “satellite phenomenon”, whereby H influenzae grow only near the beta-hemolytic S aureus colonies that produce the needed X and V factors.
What is amniotic fluid embolus syndrome?
a rare but catastrophic obstertic emergency that leads to respiratory failure and obstructive shock with an elevated central venous pressure and a decreased pulmonary capillary wedge pressure and cardiac index. It also commonly involved a consumptive coagulopathy with widespread hemorrhage.
What is seen in chronic renal allograft rejection?
Chronic renal allograft rejection manifests months or years after a transplant and presents with worsening hypertension and a gradual decline in renal function.
It involves a chronic cell mediated and antibody-mediated response against donor antigens and leads to obliterative vascular wall thickening, tubular atrophy, and interstitial fibrosis.
The process is usually irreversible and eventually leads to graft failure.
Beta-adrenergic blocking drugs on the RAAS system.
inhibit renin release by blocking beta-1 receptor-mediated regulation of the renin-angiotensin-alosterone system.
This reduces plasma renin activity, with a reduction in angiotensin I, angiotensin II, and aldosterone levels.
What happens in decompensated heart failure?
Decompensated heart failure involves a viscious cycle of hemodynamic alterations and maladaptive neurohormomal changes resulting from decreased renal perfusion.
Cardiorenal syndrome is a complication of this cycle, in which back pressure from the failing heart increases renal venous pressure to the point that the glomerular filtration rate drops substantially
what properties do first generation antihistamines (chlorpheniramine, diphenhydramine) have?
blocking histamine receptors, antimuscarininc, anti alpha adrenergic, and anti-serotonergic properties.
Anticholinergic effects on the ocular ciliary muscles impair accomodation and cause blurring of vision for close objects.
What is the most common cause of adrenal insufficiency?
Suppression of the hypothalamus-pituitary-adrenal axis by glucocorticoid therapy.
In these patients, adrenal crisis can be precipitated by stressful situations (infections, surgery) if the glucocorticoid dose is not increased appropriately.
The tissue tropism of viruses is primarily mediated by?
by viral surface glycoproteins that bind to specific host cell receptors.
Mutations to viral surface glycoproteins can alter tissue tropism and cause noninfective viruses to become infectious.
Ventricular septal defect causes?
left to right shunting with increased right ventricular pressure and if large, left sided volume overload with increased left ventricular and left atrial pressures.
A holosystolic murmur is characteristic, and failure to thrive and signs of heart failure (poor feeding, diaphoresis) can occur.
Digoxin MOA?
slows atrioventricular node conduction by increasing parasympathetic tone.
This mechanism is effective at controlling ventricular rate in atrial fibrillation at rest, but it poorly controls ventricular rate during exercise, when parasympathetic output is low relative to high levels of sympathetic tone.
Adults with coarctation of the aorta have increased risk of?
They often have chronic hypertension and are at increased risk of developing life threatening anuerysms of the aorta (dissection, rupture) and cerebral vessels (intracranial hemorrhage)
Glucose uptake in skeletal muscle is primarily via?
GLUT4
Muscle contraction and insulin induce translocation of GLUT4 to the cell surface, increasing glucose uptake during exercise and the fed state, respectively.
Over time, regular exercise causes increased expression of GLUT4, leading to increased skeletal muscle glucose uptake at any given insulin level and therefore lower blood glucose levels
MOA of etoposide
a chemotherapeutic agent that inhibits the sealing activity of topoisomerase II; causes chromosomal breaks to accumulate in dividing cells, causing cell death.
What is plasm arenin activity (PRA)?
a measure of the amount of angiotensin I generated per unit of time.
Provides a useful assessment of the renin-angiotensin-aldosterone axis.
Factors that increase PRA : low sodium intake and antihypertensive meds such as diuretics (hydrochlorothiazide), ACE inhibitors, and angiotensin II receptor blockers (valsartan)
Median nerve damage causes?
The median nerve is most commonly injured within the carpal tunnel, leading to pain and numbness in the first 3 digits and lateral half of the 4th, as well as weakness of thumb flexion and opposition.
More proximal injury (in the forearm) additionally causes decreased sensation over the thenar eminence and weakness of flexion in the wrist and second and 3rd digits.
How does 5-alpha reductase inhibitors work in androgenetic alopecia?
Androgenetic alopecia causes hair loss primarily at the anterior scalp and vertex.
It shows polygenic inheritance, with dihydrotestosterone (DHT) being the primary pathogenic factor.
5alpha reductase inhibitors decrease the conversion of testosterone to DHT and are effective for treating the condition.
What can lead to the formation of head and neck squamous cell carcinoma?
inactivation of retinoblastoma protein activity by human papillomavirus
Cancer cells avoid immune recognition by?
overexpressing programmed death ligand 1 (PD-L1), which binds to the programmed cell death-1 (PD-1) receptor on cytotoxic T cells and inhibits their response (T cell exhaustion)
Monoclonal antibodies that block PDL1 and PD1 are effective against cancers that express high levels of neoantigens on their surface because these tumors are particularly susceptible to immune recognition by cytotoxic T cells.
What increases the risk for neural tube defects (eg, anencephaly, meningomyelocele)?
Failure of neural tube closure results in neural tube defects.
Folate deficiency is the greatest risk factor, and meds that impair folate metabolism (eg, valproate) are associated with an increased risk.
The presence of what distinguishes an upper UTI from lower?
Both upper (pyelonephritis) and lower (cystitis) UTIs can show microscopic hematuria, pyuria, and bacteriuria on UA with microscopy.
However, the presence of white blood cell casts can confirm the diagnosis of pyelonephritis in patients with UTI symptoms because WBC casts form only in the renal tubules.
Name the 2 most important opsonins (coating proteins)
Opsonization occurs when host proteins such as immunoglobulins or complement bind to foreign cells such as bacteria and coat the surface, enhancing phagocytosis.
The most important opsonins (coating proteins) are immunoglobulin G and complement C3b.
Disorders involving telomerase function (eg, dyskeratosis congenita) results in?
Result in premature death of cells with high turnover, characteristically causing mucocutaneous changes (eg oral leukoplakia, dystrophic nails), bone marrow failure, and pulmonary fibrosis.
Telomerase help maintain chromosomal integrity and are preserved in rapidly dividing cell lines (epithelial cells, lymphocytes, hematopoietic stem cells) by telomerase.
Placenta acrreta spectrum occurs due to?
placental invasion into the myometrium through defects in the decidua basalis.
This creates a morbidly adherent placenta that does not detach after fetal delivery, leading to postpartum hemorrhage.
Manual placental extraction typically yields small fragments and increases bleeding.
Erythropoietin signal transduction is primarily mediated by?
Janus kinase 2/signal transducer and activator of transcription (JAK2/STAT) signaling pathway, which promotes erythrocytes precursor survival and differentiation.
Why does normocytic anemia occur in chronic kidney disease?
Chronic kidney disease is commonly associated with normocytic anemia due to reduced production of erythropoietin by the kidneys
What is the function of 21-hydroxylase?
an enzyme that converts progesterone to 11-deoxycorticosterone and 17-hydroxyprogesterone to 11-deoxycortisol.
Nonclassic congenital adrenal hyperplasia is due to?
mild deficiency of 21-hydroxylase
In adolescent girls, it presents with signs of hyperandrogenism (hirsutism, acne, menstrual irregularities) as well as increased 17-hydroxyprogesterone and testosterone levels
What is the pathogenesis of migraines?
Migraines are episodic, unilateral, throbbing headaches associated with nausea, vomitting and sensitivity to light.
The pathogenesis of migraines involves a genetic predisposition to increased cerebral excitability (eg, cortical spreading depression), which leads to abnormal neuronal activation of trigeminal afferents and the release of calcitonin gene-related peptide, a vasoactive neuropeptide involved in the transmission of pain signals
What are the functions of eosinophils?
Eosinophils play a role in host defense during multicellular parasitic infection.
When stimulated by antibodies bound to a parasitic organism, they destroy the parasite via antibody-dependent cell-mediated cytotoxicity with enzymes from their cytoplasmic granules.
Another function of eosinophils is regulation of type I HSR.
What is staphylococcal scalded skin syndrome?
Occurs in infants/children due to the production of exfoliative exotoxins by Staph aureus.
The toxins cleave desmoglein in desmosomes, leading to widespread epidermal blistering and shedding, especially with gentle pressure (Nikolsky sign). Mucous membranes are spared.
What is familial chylomicronemia syndrome?
frequently presents in childhood with recurrent episodes of acute pancreatitis.
Patients with this disorder are not usually at increased risk for premature coronary artery disease.
Eruptive skin xanthomas may be present in hypertriglyeridemia, but tendon xanthomas and xanthelasmas are primary seen with hypercholesterolemia
Hyperammonemia in advanced liver failure occurs as a direct result of the cirrhotic liver’s inability to?
metabolize nitrogenous waste products.
Ammonia crosses the blood brain barrier and causes excess glutamine to accumulate within astrocytes.
This decreased the amount of glutamine available for conversion to glutamate in the neurons, resulting in disruption of excitatory neurotransmission
Given phenotypically normal patients, the probability that a female sibling of a male affected by an X-linked recessive disease will give birth to an affected child is?
1/8
What are zinc finger motifs?
Zinc finger motifs are composed of amino acid chains bound together around a zinc ion.
They recognize specific DNA sequences are are used by many transcription factors to bind DNA and alter activity of target genes.
Intracellular receptors that act directly as transcription factors and contain zinc finger binding domains include those that bind thyroid hormone, steroids, and fat soluble vitamins.
Nosocomial bloodstream infections are usually associated with?
intravascular catheters, which allow skin commensals such as Staph aureus and coagulase-negative staph to enter the bloodstream
Primary metabolic acidosis is characterized by?
pH <7.35 (acidemia)
low serum HCO3-
compensatory low PaCo2
An anion gap [Na - (HCO3 + Cl)] above normal (ie, 10-14 mEg/L) indicates a high anion gap metabolic acidosis
Expanding space-occupying lesions can increase intracranial pressure, causing transtentorial herniation of the uncus. What can be seen in uncal herniation?
Uncal herniation often compresses the ipsilateral oculomotor nerve (CNIII) as it exits the midbrain, resulting in CN III palsy with a fixed dilated pupil (due to preganglionic parasympathetic nerve fiber damage
What is narcolepsy?
a chronic sleep disorder characterized by excessive daytime sleepiness, cataplexy, and REM sleep related phenomena (hypnagogic/hypopompic hallucinations, sleep paralysis)
What is postpartum thyroiditis?
Occurs within 12 months of pregnancy and is characterized by autoimmune destruction of thyroid follicles.
It begins with a hyperthyroid phase due to release of preformed thyroid hormone, followed by a transient hypothyroid phase due to depletion of thyroid hormone.
Histo for postpartum thyroiditis?
Lymphocytic infiltration, sometimes with formation of germinal centers
MOA of carbonic anhydrase inhibitors (acetazolamide)
block the reabsorption of sodium bicarbonate in the proximal tubule to cause metabolic acidosis.
These drugs can be used to help offset the metabolic alkalosis caused by loop diuretics
Hereditary hemochromatosis is most commonly caused by?
a missense mutation in the HFE gene, resulting in excessive intestinal iron absorption and organ damage (eg cirrhosis, diabetes, cardiomyopathy, arthropathy) due to iron accumulation within parenchymal tissues
Penetrating injury to the lung apices can lead to?
The lung apices extend above the level of the clavicle and first rib through the superior thoracic aperture. Penetrating injury in this area may lead to pneumothorax, tension pneumothorax, or hemothorax
Pulmonary embolism causes?
dead space ventilation, which leads to hypoxemia due to the consequent ventilation/perfusion mismatch
Patients being weaned from mechanical ventilation typically breathe at what volumes?
low tidal volumes, with a compensatory increase in respiratory rate to maintain minute ventilation.
Because at low tidal volumes a higher proportion of each breath is composed of dead space, this type of breathing leads to an increase in wasted ventilation (inefficient breathing)
Critical illness can lead to weakness due to?
due to both myopathy (atrophy of muscles) and polyneuropathy (axonal degeneration, decreased nerve excitability)
This can lead to both extremity weakness and difficulty breathing due to chest wall weakness
common fibular nerve injury symptoms
The common fibular nerve is sperficially located at the proximal fibula, leaving it vulnerable to injury by compression by the fibular head (prolonged lying on the affected side).
Patients typically have weakness of foot dorsiflexion (footdrop), foot eversion, and toe extension, along with sensory loss over the lateral lower leg and dorsal foot
Histopathologic findings in Crohn disease?
Crohn disease is an inflammatory bowel disorder that causes patchy inflammation throughout the GI tract.
Characteristic histopath findings: noncaseating granulomas, transmural inflammation, and Paneth cell metaplasia
What plays a central role in the pathogenesis of Crohn disease?
Tumor necrosis factor-alpha, a cytokine produced by macrophages, plays a central role in the pathogenesis of Crohns
anti-TNF alpha agents (infliximab, adalimumab) are often used as first line therapy
What is responsible for increased pain in neuromas?
A neuroma forms when regnerating axons are unable to find their distal target and create a haphazard mass of axons and supporting cells.
Upregulation of voltage gated sodium channels, which generate and propagate action potentials, is likely responsible for the increased pain of these lesions.
Cryptococcus neoformans stains
Crpyto neoformans is the only pathogenic fungus that has a polysaccharide capsule.
The capsule appears red on mucicarmine stain and as a clear unstained zone with India ink
