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acne vulgaris
presentation: nodules, cysts, papules, pustules, open/closed comedones
etiology:
sebum/androgen production
abnormal keratinocyte desquamation
C. acnes colonization of pilosebaceous unit
inflammation
anthrax
Bacillus anthracis
Edema toxin mimics cAMP
Lethal toxin → septic shock and death
RF: occupational exposure from direct contact w/ infected animals and carcasses
i.e taxidermist
Cutaneous:
painLESS papule → vesicle → black eschar ulcer (painless and necrotic) → bacteremia and death
Pulmonary:
via inhalation of spores
flu-like rapidly progresses to fever, pulm hemorrhage, mediastinitis, and shock
Woolsorter’s disease
CXR: widened mediastinum
Bacillary Angiomatosis
Bartonella henselae or quintana
erythematous violaceous papules to nodules
RF: immunocompromised
Dx: Warthin-Starry silver stain
Botulism
Clostridium botulinum
heat labile
MOA: inhibits ACh release from NMJ
adults ingestion preformed toxin
babes ingest spores → floppy baby syndrome, descending flaccid paralysis
si/x:
diplopia
dysarthria
dysphagia
dyspnea
Ehrlichiosis
Ehrlichia chaffeensis
vector: tick
fever, HA, malaise
maculopapular rash
leukopenia
thrombocytopenia
increased ALT/AST
monocyte w/ morulae B in cytoplasm
mulberry like inclusion
Leprosy
Mycobacterium leprae
reservoir: armadillos
MC in India and Africa
“Hansen dz”
Lepromatous:
diffusely over skin
leonine facies
communicable → high bacterial load
low CMI
Th2 response
Tuberculoid:
few hypoesthetic hairless skin colored plaques
high CMI
Th1 response
low bacterial load
Lyme Disease
Borrelia burgdorferi
transmission: ixodes deer tick
reservoir: mouse
MC in NE US
Stage 1: early localized, erythema migrans bullseye configuration, flu-like symptoms
Stage 2: early disseminated, carditis, AV block, Bell’s palsy, migratory myalgia, transient arthritis
Stage 3: late disseminated, encephalopathy, chronic arthritis
RMSF
Rickettsia rickettsii
vector: tick
MC in South Atlantic, esp NC
rash starts at wrist and ankle → trunk, palm, sole
HA
fever
rash
Staphylococcus
MC in nares, ears, axilla, and groin
results in skin infx associated w/ hair follicles and carbuncles, organ abscesses, pneumonia (after influenza virus infx), endocarditis, septic arthritis, osteomyelitis
MRSA: serious nosocomial and community-acquired infx due to altered penicillin binding protein
Scalded Skin Syndrome
fever
generalized erythematous rash
sloughing of upper layers of epidemis
(+) Nikolsky sign
MC in newborns and children, or adults w/ renal insufficiency
(-) blood culture
Toxic Shock Syndrome
severe multisystem disease w/ cutaneous and internal involvement
menstrual: young women w/ superabsorbent tampons
nonmenstrual: nasal packing
fever
hypoTN
scarlatiniform eruption
palmoplantar desquamation
Erysipelas
sharply defined fiery red plaque
superficial variant of cellulitis in upper-mid dermis
(-) culture
increased DNase B and ASO titer
MC: streptococcus pyogenes
Scarlet Fever
GAS pharyngitis
fever
sore throat
blanching macular erythema
sandpaper like body rash
strawberry tongue
circumoral pallor
(+) erythrogenic toxin
(+) culture
elevated DNase B and ASO titer
Primary Syphilis
painLESS chancre
dark field microscopy to visualize treponemes
(+) VDRL in 80%
Secondary Syphilis
copper colored maculopapular rash
condyloma lata: smooth painLESS wart like lesion on genitals
lymphadenopathy
patchy hair loss
confirm w/ dark field
VDRL/RPR and FTA-ABS
Tertiary Syphilis
gumma (chronic granuloma)
aortitis (vasa vasorum destruction)
neurosyphilis (tabes dorsalis, general paresis)
argyll roberston pupil
broad based ataxia
(+) Romberg
Charcot joint
stroke w/o HTN
Congenital Syphilis
rhagades: linear scar at angle of mouth
snuffles w/ nasal discharge
saddle nose
notched Hutchinson teeth
mulberry molars
short maxilla
saber shins
CN8 deafness
treat mother in 1st trimester
Tetanus
Clostridium tetani
tetanospasmin block release of GABA and glycine from Renshaw cells
spastic paralysis
trismus lockjaw
risus sardonicus: raised eyebrows and open grin
opisthotonos: spasm of spinal extensors
Endemic Typhus
Rickettisia typhi
vector: flea
fever
erythematous macules and papules
rash starts centrally and spreads out
sparing palms and soles
Epidemic Typhus
Rickettsia prowazekii
human body louse
fever
erythematous macules and papules
rash starts centrally and spreads out
sparing palms and soles
cellulitis
acute painFUL spreading infx of deeper dermis and SQ tissues
fever
MCC: S pyogenes or S aureus
RF: break in skin from trauma or another infx, immunosuppressed
unilateral
impetigo
very superficial skin infx
MC in children
MCC: S aureus or S pyogenes
highly contagious
honey colored crusting
bullous impetigo has bullae and is caused by S aureus
Necrotizing Fasciitis
deeper tissue injury involving skin, SQ, and fascia
MCC: anaerobic bacteria or S pyogenes
painFUL woody indurated plaque
pain out of proportion
dusky purple gray
fever
tachycardia
septic shock
crepitus from methane and CO2 production
RF: immunosuppressed
Blastomycosis
blastomyces dermatitidis
E and Central US
broad based budding
inhalation w/ hematogenous spread
pulmonary manifestations MC
secondary cutaneous lesion in immunosuppressed → verrucous nodules, abscesses, and ulcers
Candidiasis
Candida albicans
oral/esophageal thrush in immunocompromised
cottage cheese like
vulvovaginitis in DM, abx use
diaper rash
beefy red w/ satellite pustules and or erosions
endocarditis in IVDA
disseminated in neutropenic pts
chronic mucocutaneous candidiasis
dx: KOH yeast and pseudohyphae
Histoplasmosis
MC in Mississippi and Ohio River Valley
macrophage filled with histoplasma → smaller than RBC
inhlalation of birds and bat feces
fever
skin involvement MC in immunosuppressed
primary cutaneous chancre w/ lymphangitis
pulm manifestations MC
palatal/tongue ulcers
splenomegaly
Paracoccidiodomycosis
Paracoccidiodes brasiliensis
MC in Latin America
budding yeast w/ captain’s wheel
much larger than RBC
inhalation of infected soil
granulomatous ulcerative oropharyngeal and perioral involvement
MC in males
Coccidiodomycosis
Coccidiodes immitis
SW US, CA
spherule filled w/ endospores
much larger than RBC
inhalation w/ dissemination
verrucous nodules/papules, pustules, abscesses or ulcerative lesions
MC pulmonary manifestations
erythema nodosum or multiforme
arthralgia
can cause meningitis
Sporotrichosis
Sporothrix schenckii
Endemic to Central/South America and Africa
dimorphic
cigar shaped budding yeast w/ branching hyphae and rosettes of conidia
spores traumatically induced usually by thorn
local pustule/ulcer w/ nodules along draining lymphatics → ascending lymphangitis
disseminated in immunocompromised host
tinea
dermatophytes: microsporum, trichophyton, epidermophyton
pruritus
tinea capitis: head and scalp
lymphadenopathy, alopecia, and scaling
tinea corporis: torso
erythematous scaling, ringworm, central clearing
acquired from cat or dog
tinea cruris: inguinal area
does not show central clearing
tinea pedis:
MC interdigital
moccasin distribution
vesicular type
tinea unguium: nails
branching septate hyphae on KOH prep w/ blue fungal stain
tinea pityriasis versicolor
Malassezia
yeast like fungus
hypo/hyperpigmented and or pink patches due to degradation of lipids producing acids that damage melanocytes
less pruritic
MC in summer, hot humid weather
dx: spaghetti and meatballs on KOH
hairy leukoplakia
EBV
transmission: saliva or blood
infect B cells
irregular, white, painLESS plaques on lateral tongue that cannot be scraped off
RF: immunosuppressed
Hand, Foot, Mouth disease
Coxsackie A16 virus
transmission: fecal-oral, respiratory
prodromal fever and malaise
oval shaped vesicle on erythematous base on palms, soles, and oral cavity
Herpes Labialis
HSV1
clustered vesicles on erythematous base on orolabial region
dormant in sensory dorsal root trigeminal ganglia
transmission: contact w/ saliva
dx: Tzanck
HSV1
resp secretions
saliva gingivostomatitis
keratoconjunctivitis
herpes labialis
herpetic whitlow on fingers of dentists
temporal lobe encephalitis → sporadic w/ altered mental status, seizures, and aphasia
esophagitis
erythema multiforme
latent in trigeminal
HSV2
transmission: sexual contact, vertical
viral meningitis
latent in sacral ganglia
painFUL erosion and vesicles
Molluscum Contagiosum
Poxvirus
umbilicated papules
MC in children
STI in adults
5th disease/Erythema Infectiosum
Parvovirus B19 virus
single stranded linear (smallest DNA virus)
transmission: resp secretion, blood or placental
prodromal → fever, myalgia, HA
“slapped cheek” w/ maculopapular lacey eruption
in fetus → hydrops fetalis, death
aplastic crises in sickle cell disease
pure RBC aplasia and RA
Roseola
6-24m of age
higher fever → seizures
diffuse rose-colored macular rash
fever first then rash
MCC: HHV6 and HHV7
Rubella
Togavirus
infx begins in nasopharynx → LN → viremia
prodrome fever and URI
fine maculopapular rash starting on face and spreads centrifugally to involve trunk and extremities
postauricular LN
arthralgia
blueberry muffin due to extramedullar hematopoiesis
Measles
Paramyxovirus
Transmission: resp droplets
prodromal → cough, coryza, conjunctivitis
Koplik spots: bright red spots w/ blue-white center on buccal mucosa
1-2 days later, maculopapular rash that starts at head/neck and spreads downward
lymphadenitis
Warthin-Finkeldey giant cells in background of paracortical hyperplasia
Varicella
Varicella-Zoster virus
Transmission: resp secretion
prodromal → fever, fatigue, myalgia
multiple crops of lesions
dew drops on rose petals → vesicle on erythematous base
begins on trunk and spreads to face and extremities
complications: encephalitis, pneumonia, Reyes Syndrome
dx: IgG
Herpes Zoster
Varicella-Zoster virus
reactivation from dorsal root/trigeminal ganglion in dermatomal distribution
prodrome → pruritus and pain
painFUL grouped vesicles on an erythematous base
complication: postherpetic neuralgia
Verrucae Warts
Common Warts:
hyperkeratotic papules w/ pinpoint black dots
HPV 1/2/4
Condyloma Acuminata:
genital warts → smooth sessile skin-colored to brown lobulated papules
HPV 6/11
Cervical Intraepithelial Neoplasm:
HPV 16/18
African Trypanosomiasis - African Sleeping Sickness
T brucei gambiense/rhodesiense
enlarged LN
recurring fever (antigenic variation)
somnolence
coma
transmission: Tsetse fly → painFUL bite
dx: trypomastigote in smear
American Trypanosomiasis - Chagas Disease
Trypanosoma cruzi
MC in South America
unilateral periobital swelling → Romana sign
transmission: triatomine, feces deposit in painLESS bite
complication: dilated cardiomyopathy w/ apical atrophy, CHF, megacolon, megaesophagus
dx: trypomastigote in smear
Babesiosis
Babesia equi
MC in NE US
fever
HA
hemolytic anemia
RF: asplenia
transmission: Ixodes tick
dx: ring form C1, Maltese cross
Cutaneous Larva Migrans - Hookworms
Ancylostoma duodenale, Necator americanus
transmission: larvae penetration walking barefoot on contaminated beach
pruritic
serpiginous rash
iron deficiency anemia from sucking blood from intestinal wall
eosinophilia
Leishmaniasis
L donovani, tropica, braziliensis
Visceral → spiking fever, hepatosplenomegaly, pancytopenia
Cutaneous → skin ulcers
transmission: sandfly
dx: macrophages containing amastigotes
Schistosomaiasis - Swimmer’s Itch
trematode fluke
intermediate host: snails
tranmission: contaminated fresh water
S Mansoni
lateral spine
hepatosplenomegaly
fibrosis
inflammation
portal HTN
ascites
esophageal varices
S Haematobium
terminal spine
squamous cell carcinoma of bladder
painLESS hematuria
pulmonary HTN
Threadworm
Strongyloides Stercoralis
larvae in soil penetrate in feet → larval phase in lung → swallow and molt in adults entering intestinal mucosa and lay eggs → hatch into rhabditiform into intestinal lumen and passed into stool
abdominal pain
diarrhea