Derm Flashcards
Young children, outbreaks common in daycare
- Low fever; mouth and throat pain; vesicular lesions on tongue, buccal mucosa, pharynx or lips
- Nonpruritic skin lesions on hands, feet, buttocks, legs, or arms that are maculopapular, vesicular, or pustular
- mucosal lesions rapidly progress to vesicles that erode and become surrounded by an erythematous halo
coxsackie A, hand foot and mouth disease
- nonenveloped, linear ssRNA virus
- MC in summer/early fall
proliferation of endothelial cells caused by human herpesvirus-8 (HHV-8) in immunocompromised individuals (AIDS)
- lesions may be cutaneous or visceral
- nearly all patients develop skin lesions, and there are usually multiple lesions on both sides of the body with a symmetrical distribution
- mucous membrane involvement is common
- may be painful, but are not pruritic
Kaposi sarcoma
- lungs and GI tract commonly involved
nonenveloped, linear ssDNA virus
- “slapped cheek”
- children aged 3-15
- spread via aerosolized respiratory droplets
Erythema Infectiosum aka Fifths disease
- caused by parvovirus B19
- low-grade fever, headache, coryza, pharyngitis, nausea, and malaise
- rash starts on face, followed by lacelike rash on the trunk and extremities
9-12 month old who develops high (4 day) fever
- followed by a macular rash over the body
Roseola
- HHV6, enveloped, linear dsDNA virus
what is the other name for measles?
Rubeola
- maculopapular rash begins on the face and, over 48 hours, starts to coalesce into patches and plaques that spread caudally to the trunk and extremities, including palms and soles
- transmitted via respiratory droplets
fever, exudative pharyngitis, and a scarlatiniform rash
- rash begins initially on the groin and armpits and proceeds to involve the trunk and then the face and extremities
Scarlet fever, S. pyogenes
- occurs due to a delayed-type skin reactivity to pyrogenic exotoxins (erythrogenic toxins A, B, C) production from the bacteria
dimorphic fungus, caused by landscaping/gardening scratches
- Days to weeks after cutaneous inoculation, a papule develops at the site of inoculation
- primary lesion ulcerates; drainage from the lesion is not grossly purulent and has no odor
- similar lesions occur along lymphatic drainage channels
Sporothrix schenckii
hot tub folliculitis
pseudomonas
- has sweet, grape-like odor when cultured
fever, fatigue, body aches, generalized weakness, and a tender erythematous rash
- asymmetric polyneuropathy, can cause both motor and sensory deficits
- associated with HBV infection, usually within the last 6 months
PAN
- small-med vessels, particularl renal, cardiac, and GI
Young Asian female (< 40 years old), weak upper extremity pulses
Takayasu arteritis
Older females, unilateral headache, jaw claudication may lead to blindness
- Associated with polymyalgia rheumatica
Giant cell arteritis
Asian children, conjunctival injection, strawberry tongue, desquamating rash on hands and feet
- aortic dissection, AMI
Kawasaki
Heavy smokers, autoamputation of digits, Raynaud phenomenon
Thromboangiitis Obliterans
Buerger disease
p-ANCA (anti-MPO), lungs and kidney affected, similar to Wegener’s, but no nasopharyngeal involvement
microscopic polyangiitis
c-ANCA (anti-proteinase 3), upper airway, lungs, kidneys, saddle-nose deformity
GPA aka Wegener’s
P-ANCA, high eosinophilia, mononeuritis multiplex
Eosinophilic granulomatosis w/Polyangitis aka Churg-Strauss
- Mononeuritis multiplex is a painful, asymmetrical, asynchronous sensory and motor peripheral neuropathy involving isolated damage to at least 2 separate nerve areas
Often after URI or gastroenteritis, 90% occurs in children
- palpable purpura, arthritis/arthralgias, abdominal pain, hematuria
IgA Vasculitis (Henoch-Schönlein purpura)
what is the medical name for cradle cap?
seborrheic dermatitis
- greasy-looking, yellow scales on an erythematous base
- or scaly, oily, salmon-colored plaques
what is the medical name of eczema?
atopic dermatitis
- causes intense pruritis
- extensor surfaces (in adults)
- dry, scaly, or excoriated erythematous papules
rash begins as vesicles and pustules filled with serous fluid that rupture and turn into honey-colored crusted lesions on an erythematous base
impetigo
- S. aureus or S. pyogenes
superficial, painful blisters that rupture very easily
- autoantibodies against desmosomes
- type II hypersensitivity reaction
pemphigus vulgaris
tense bullae at the subepidermal or dermal-epidermal junction
- autoantibodies against hemidesmosomes
- do not easily rupture
bullous pemphigoid
Treatment of tinea corporis?
topical antifungals miconazole, clotrimazole, or ketoconazole
cutaneous lesions during infancy or early childhood and consists of reddish-orange or yellowish-brown scaly papules, erosions, or petechiae in the groin, intertriginous regions, and scalp
langerhans histiocytosis
what is the Auspitz sign and when would you see it?
scratching of a silvery psoriasis plaque, leads to microbleeding
hyperkeratosis, parakeratosis, acanthosis, rete pegs are elongated, dermal papillae are elongated and hypervascular, mitotic figures above the basement membrane
psoriasis
Abundant dermal and epidermal lymphocytes with epidermal necrosis
erythema multiforme
- Severe cases can transform into Stevens-Johnson syndrome, with necrosis of much of the epidermis and possible death
Irregular acanthosis, a band of lymphocytes below the epidermis, and a damaged basal layer
- occurs on the flexor surfaces, especially the wrists
- patients often have white, lace-like lesions in the mouth
lichen planus
Septate branching hyphae within the stratum corneum
tinea corporis
what causes tinea versicolor/pityriasis versicolor?
- hypopigmented or hyperpigmented macules and patches normally localized to sebum-rich areas like the chest or back
malassezia furfur
- organism degrades lipids in the skin leading to a production of acids that damage melanocytes and cause the macules and patches of discoloration
- spagetti and meatball on KOH!
flesh-colored or erythematous, asymptomatic annular plaques with a firm, ropy border and central clearing. They begin as small lesions and may show slow, centrifugal growth
- usually on dorsal surfaces of hands/feet, wrists/ankles
Granuloma annulare
- punch bx needed to confirm
“dew drops on a rose petal” or small vesicles on an erythematous base that are extremely pruritic
varicella zoster
anti-histone Ab?
drug-induced lupus
- isoniazid, procainamide, hydralazine
Anti-microsomal antibodies?
Hashimoto’s thyroiditis
what is the bad complication of measles?
subacute sclerosing panencephalitis (SSPE)
- often fatal, progressive, degenerative disease of the CNS
- typically an asymptomatic period of 6-15 years between the initial infection and the development of SSPE
Congenital albinism is often due to a deficiency in what?
tyrosinase
- enzyme needed for converting tyrosine to melanin
hypopigmentation of the skin due to lack of tyrosine
- but it is often associated with peculiar body odor and altered brain function including intellectual disability
phenylketonuria
IgM antibodies that recognize the Fc portion of IgG
rheumatoid factor
porphyria cutanea tarda
?
middle aged men
- benign neoplasm of fat cells
- MC benign soft-tissue neoplasm in adults
- round, painless, moveable mass usually found encased in a thin fibrous capsule
- mature univacuolated adipocytes with small nuclei
lipoma
most common sarcoma of adulthood. It usually arises in deep soft tissues of the extremities and retroperitoneum
- lipoblasts, with multiple cytoplasmic vacuoles of lipid that scallop the nucleus, and myxoid stroma
liposarcoma
benign, soft tissue mass composed of smooth muscle, most commonly found in the uterus
leiomyoma
virulence factor of S. pygenes involved in blocking phagocytosis by interfering with C3b binding for opsonization
- antibodies can bind to heart antigens by a process of molecular mimicry and cause rheumatic fever, a type II hypersensitivity reaction
M protein
virulence factor of S. pygenes that act as superantigens
- responsible for the development of scarlet fever rash as well as severe clinical manifestations like necrotizing fasciitis and TSS
Spe toxins (SpeA, SpeB, SpeC, SpeF)
when do you see pyoderma gangrenosum?
UC
- 2nd MC skin infection in IBD, after erythema nodosum
- remember the association of UC and PSC!
what does parainfluenza virus cause in young children?
croup
what is the tx for Sporothrix schenckii?
itraconazole
parasite is transmitted by the black fly, which is found in Africa, Yemen, and parts of South America
- majority of cases are found in the continent of Africa
- second-leading infectious cause of blindness worldwide
onchocerciasis
- aka river blindness
- tx: ivermectin
parasite that causes swelling of the skin and presence of subcutaneous worms
- infects the conjunctiva of the eye, in which worms are visible
- rarely leads to blindness
- transmitted by Chrysops flies (including the deer fly, horse fly, and mango fly
Loa Loa (loiasis) - tx: diethylcarbamazine
spiking fevers, hepatosplenomegaly, and pancytopenia
- transmitted by the sandfly
- commonly found in India
Kala-azar, aka visceral leishmaniasis
- parasite Leishmania donovani.
what is the precursor for SCC of the skin?
actinic keratosis ("solar keratosis")
- patch of epidermis where the cells show features of precancer (abnormal nuclei, irregular arrangement) but have not yet invaded- neurofibromas anywhere along the path of cutaneous nerves
- irregularly shaped, evenly pigmented, brown macules (café-au-lait spots)
- Lisch nodules
- pheochromocytomas
- optic gliomas
- increased tumor susceptibility
neurofibromatosis type 1 (AD)
- mutation of tumor-suppressor gene on the long arm of xsome 17
inheritance pattern of cystic fibrosis, Tay-Sachs disease, glycogen storage diseases, and phenylketonuria?
AR
inheritance pattern of hemophilia A, Hunter syndrome, and G6PD deficiency?
X-linked R
deficiency in the essential amino acid tryptophan
- defects in intestinal absorption and renal tubular reabsorption
Hartnup dz
- Tryptophan is the precursor to nicotinamide and nicotinate — 2 forms of niacin (vitamin B3)
- leads to a deficiency in niacin -> pellagra
essential AA that is important precursor to tyrosine, necessary for thyroid hormone, dopamine, and melanin formation
- hypopigmentation from decreased melanin
- mental retardation from decreased Dopa and NE
- musty urine
phenylketonuria
- defects in phenylalanine hydroxylase lead to an accumulation of phenylalanine and deficiency of tyrosine, thyroid hormone, dopamine, and melanin
- conversion/excretion of phenylalanine -> phenyl ketones = musty urine
high fevers, intense headaches, myalgias, and tender lymphadenopathy in axillary, inguinal, and cervical regions
- can also necrose the fingertips
Yersinia pestis
- effective bioterrorism weapon
MPO-ANCA (p-ANCA)?
microscopic polyangiitis (MPA)
- Renal biopsy and pulmonary biopsy are common and most frequently show pauci-immune glomerulonephritis, which is often diffuse and necrotizing with crescentic formation
- usually lacks granulomatous inflammation in the tissue surrounding the vasculitic small vessels -> DIFFERENT FROM GPA
PR3-ANCA (c-ANCA)
granulomatosis w/ polyangiitis (GPA)
- NOTE: c-ANCA = cytoplasmic staining form
- café au lait spots
- axillary freckling
- neurofibromas of peripheral nerves
- pigmented nodules in the iris (Lisch nodules)
neurofibromatosis type 1 (AD)
- inactivation of the tumor suppressor gene NF1 found on Chromosome 17
mutation in HFE gene?
hemochromatosis
Gram-negative pleomorphic bacterium (coccobacillus)
- MC presentation in adults is ulceroglandular — a punched out ulcer at the site of inoculation with suppurative lymphadenopathy
- can also contaminate the eyes and lungs
- in central-southern states (pt hunting in Missouri/Arkansas)
tularemia
what disease is transmitted by the dermacentor (dog) tick?
rocky mountain spotted fever
what is the tx for MRSA?
IV vancomycin
- binds the D-alanyl-D-alanine portion of the cell wall to block glycopeptide polymerization
what is the MC side effect of vancomycin?
Flushing, known as “red man” syndrome
- can be avoided by a slower infusion rate and co-administration with antihistamines
what is the MC side effect of metronidazole?
disulfram rxn
what bad side effect is most commonly associated with sulfonamides, penicillins, ethosuximide, lamotrigine, carbamazepine, phenobarbital, phenytoin, and allopurinol
Steven-Johnson syndrome
when would you see pigmented hamartomas in the iris called Lisch nodules?
NF type 1
proliferations of the cells of the peripheral nerves, especially Schwann cells and fibroblasts
neurofibromas
when would you see bilateral acoustic neuromas, which histologically are schwannomas?
neurofibromatosis type 2
- meningiomas, spinal ependymomas, cataracts, and neuropathies
what is a common side effect of tetracycline
photosensitivity
what is the quadruple therapy for PUD?
Bismuth subsalicylate
an H2 blocker such as ranitidine
metronidazole
tetracycline
what does a negative nitroblue tetrazolium (NBT) staining indicate?
Chronic Granulomatous Disease
- NBT test displays the reactive oxygen species produced by NADPH oxidase; a positive test stains as a blue color indicating the presence of oxidase and subsequent reactive oxygen species
- CGD is caused by a defect in NADPH oxidase which impairs oxygen-dependent microbial killing in phagocytes. Therefore, because the oxidase enzyme is lacking in CGD, the NBT test will be negative
oval, slightly raised 2-cm to 5-cm plaque or patch with a peripheral scaly appearance
- secondary eruption consists of lesions of the same appearance but smaller and in a tree-like pattern
- usually on trunk and proximal extremities
pitryasis rosacea
- tx is supportive, and the rash resolves spontaneously within 6-10 weeks
diffuse maculopapular rash in a sexually active pt that can involve the trunk, palms, and soles
secondary syphilis
- rash generally appears 2-6 months after a primary syphilis infection
neonate with intrauterine growth restriction, jaundice, hepatosplenomegaly, periventricular calcifications
- once born, petechiae/purpura, chorioretinitis, jaundice, seizures, sensorineural hearing loss
CMV
- blueberry muffin baby
triad of eye problems (cataracts), deafness, and congenital heart disease (most often PDA)
congenital rubella
baby born with notched teeth and saddle nose?
congenital syphilis
why are tetracyclines are not indicated in pregnant or pediatric patients?
they can cause tooth enamel discoloration and growth abnormalities
what is preferred tx for lyme dz in pregnancy?
beta-lactam antibiotics (amoxicillin or ceftriaxone), which inhibit transpeptidase
bind to the 23S rRNA of the 50S subunit and inhibit protein synthesis by blocking translocation
macrolides
- erythromycin, azithromycin, and clarithromycin
what maternal infection can cause hydrops fetalis?
parvovirus B19
premature infant w/significant rhinitis (“snuffles”), hemolytic anemia, thrombocytopenia, a skin rash involving the palms and soles, and hepatomegaly
syphilis
- sabre shins, saddle nose deformity
what is the treatment for scabies?
permethrin
- targets the sodium voltage-gated channels in the parasite leading to death of the insect
can also give ivermectin if not pregnant
- causes an increase in cell membrane permeability with eventual death of the parasite
what is the tx for Loa Loa?
diethylcarbamazine (DEC)
- antihelminthic drug that acts by inhibiting arachidonic acid metabolism in filarial microfilaria, which disrupts their membranes and makes them more susceptible to immune attack
tinea capitis fungus that produces many large football-shaped macroconidia
Microsporum
what is Leser-Trélat a sign of?
- sudden appearance of multiple pruritic seborrhic keratoses
possible GI malignacy
- watch out for fatigue (likely iron deficiency anemia) and signs of GI obstruction with constipation.
what is acanthosis nigrcans a sign of?
- insulin resistance
- gastric adenocarcinoma
Lyme dz with co-infection causing hemolytic anemia, splenomegaly and jaundice
babesia microti
- maltese cross under microscope
Edema toxin produced by what, is an adenylate cyclase that increases cAMP levels by catalyzing the reaction of ATP to cAMP?
Bacillus anthracis
what organism causes overactivation of host cell adenylate cyclase through inhibition of the adenylate cyclase inhibitory Gi alpha subunit protein
Bordetella pertussis
what organism ADP-ribosylates the Gs alpha subunit protein, increasing the protein’s adenylate cyclase activity and increasing cAMP levels
V. cholera
what gram-negative bacillus that is extremely difficult to culture; and is best grown in cysteine-glucose-blood agar?
Francisca tularensis
- similar to yersinia, but has an ulceroglandular lesion that grows, and will rupture, producing a yellow exudate that may turn black
neurotoxin can cause muscle pain in the extremities, abdomen, and back
- other sx include cramping, abdominal pain, weakness, headache, nausea, vomiting, and tremor
- bites are very rarely life threatening, and sometimes there is localized diaphoresis in the affected muscle groups
black widow bite
what organism is MC associated with burn victims?
pseudomonas
- tx: aminoglycosides (bind 30s), penicillin
spongiosis of the epidermis along with epidermal acanthosis and hyperkeratosis
atopic dermatitis
- flexor surfaces in adults
- extensor surfaces kids <2
painful blisters on hands and forearms
- darkened urine
- excess hair growth on the face, forearms, and hands
- hyperpigmentation/hypopigmentation of the hands
- risk factors include alcoholism, hepatitis C, and iron overloaded states
porphyria cutanea tarda (AD)
- deficiency in uroporphyrinogen III decarboxylase, an enzyme involved in 5th step of heme synthesis
- results in porphyrins being deposited in the skin causing cutaneous fragility leading to blistering of the hands, forearms, and face
what vessels are most at risk for ischemia and necrosis with vasoconstriction caused by epinephrine?
end organs with small capillaries (fingers/toes, ear)
dermacentor tick, but saddleback fever?
- cycles with a fever for 2-3 days followed by absence of fever 2-3 days
colorado tick fever
skin thickening w/ systemic sx
- dysphagia, arrhythmias, mild proteinuria and hypertension, and respiratory complications with a restrictive lung defect
diffuse systemic sclerosis
- anti-DNA-topoisomerase (anti-Scl-70) Ab is highly specific for systemic sclerosis
- Anticentromere Abs are more characteristic of *limited scleroderma (CREST syndrome)
joint pain/swelling, fatigue, muscle weakness, and sclerodactyly
- positive, speckled antinuclear antibody and an anti-U1-RNP antibody
mixed CT disease
dysplastic nevus syndrome, is associated with an increased risk of what?
pancreatic cancer
- numerous (> 50) nevi and a first degree family member with melanoma
- likely has familial atypical mole and multiple melanoma syndrome (FAMMM syndrome) aka dysplastic nevus syndrome
- eruptive xanthomas result from what?
- tuberous and planar xanthomas result from what?
- eruptive xanthomas -> hypertriglyceridemia
- tuberous and planar xanthomas -> hypercholesterolemia
what are the most important prognostic indicators for malignant melanoma?
depth and ulceration
radiographic findings of a lesion with a lytic center and surrounding ring of sclerosis?
osteomyelitis
what drug is used to treat Pasteurella multocida infections resistant to first-line treatment of dog or cat bites
Imipenem/cilastatin
- Imipenem = beta-lactamase–resistant cell wall synthesis inhibitor
- cilastatin = renal dehydropeptidase I inhibitor
- Combining the 2 drugs allows the dose of imipenem to be reduced, thereby decreasing the risk of adverse events
what causes scalded skin syndrome?
- presents with a fever and generalized erythematous rash
- rash becomes pustular and bullous, and if a shearing force is applied by a finger, will show sloughing of the upper layers of the epidermis (Nikolsky sign) that heals completely without scarring
caused by the exfoliative toxins produced by Staphylococcus aureus
- typically seen in newborns
a superantigen, which binds MHC-II and T-cell receptors outside of the antigenic groove, nonspecifically activating large numbers of T cells to stimulate release of IFN-γ and IL-2
- is responsible for the symptoms of high fever, low blood pressure, rash, and multiple-organ abnormalities
toxic shock syndrome toxin-1 (TSST-1)
mutation in nucleotide excision repair?
Xeroderma pigmentosum
- fair skinned baby, severe sun sensitivity
- areas of hypo/hyper-pigmented skin
- can develop skin malignancy as early as 5-6 y/o
- chronic hyperkeratosis
- lymphocytic infiltrates at dermo-epidermal junction
- scattered, eosinophillic colloid (civatte) bodies in papillary dermis
- thickened stratum granulosum with sawtooth rete ridges
lichen planus
- white lacey appearance
- 6 P’s
- on flexoral surfaces of wrists, ankles
