Dermatology 1 Flashcards
Impetigo and ecthyma: etiology
- Usually S.aureus or group A Streptococcus, both common skin flora
- Minor breaks in the skin
- Secondary “impetiginization” of eczema, insect bites, burns, or other underlying dermatoses
Impetigo and ecthyma: prevalence
- Very common in the young
- Common in people kept in close quarters with poor hygiene
- Usual presentation in just a few days, accounts for 10% of visits to dermatology clinics
GAS impetigo: characteristics
- Usually found on the face
- “Honey crusted” erosions becoming confluent, or multiple small pustules eroding and coalescing to form larger ones
GAS impetigo: DDx
- Bullous impetigo
- HSV outbreak
- Dermatophytosis
- Trauma
GAS impetigo: Tx
- Mupirocin ointment (Bactroban) TID to affected areas and the anterior nares
- Pt & others close to Pt should wash w/ antibacterial bar soap (e.g. Dial) daily
Bullous impetigo: Characteristics
- Multiple confluent bullae containing clear or slightly turbid fluid, easily broken
- When unroofed, a moist and shallow erosion is present
- Bullae are usually 1-3cm in diameter,
- Can occur anywhere but the palms and soles are spared
Bullous impetigo: DDx
- HSV, varicella, zoster
- Allergic conditions
- Thermal injuries
Bullous impetigo: Tx
- Carefully unroof and apply mupirocin ointment (Bactroban) TID to affected areas
- 5 day course
Ecthyma: Characteristic
- A large unroofed bulla that started as bullous impetigo, unroofed
- Forms an ulceration with a thickened, crusty or moist base that is occasionally necrotic
- Takes wks to form, often encountered on the legs
Ecthyma: DDx
- Vascular insufficiency
- Factitious disorders
- Diphtheria (very rare in the US)
Ecthyma: Tx
- Tx is usually systemic
Preferred- Decloxacillin or Cephalexin; if MRSA suspected/confirmed- Clindamycin, TMP-sulphamethoxasol (Bactrim), or Doxycyclin
Abscess: Characteristics
- A well-circumscribed collation of pus appearing as an acute or chronic localized infection and associated with tissue destruction
Abscess: Etiology
- Is most often caused by Staphylococcus spp
- Usually the result of some kind of wound infection or trauma
- Occurs gradually over days, sometimes weeks
Abscess: Sx
There is usually throbbing pain and the area is exquisitely tender
Abscess: Tx
- The treatment involves incision and drainage
Note: There is a fair amount of evidence to suggest that systemic treatment is not necessary unless constitutional symptoms are present
Furuncle: Characteristics
An acute, deep-seated, red, hot, tender nodule that may or may not have an abscess
Furuncle: Etiology
Is always associated with a hair follicle, is sometimes an “ingrown hair” related to depilatory treatments gone wrong
Furuncle: DDx
Hidratenitis suppurativa (comedolike follicular occlusion, chronic relapsing inflammation, mucopurulent discharge, and progressive scarring)
Furuncle: Tx
Is handled the same as with an abscess if pus is present, if the nodule has no lake of pus present, hot compresses can be applied and systemic antibiotics can be given
Furuncle: Prevention
Instruct Pts to trim instead of shave or change a razor blade frequently
Carbuncle: Characteristics
- A deeper infection comprised of interconnecting small abscesses usually arising in several contiguous hair follicles
- Arise slowly, over weeks
Carbuncle: Tx
- Usually requires drainage of as many of the pustules as possible, warm compresses, strict hygiene and topical as well as systemic antibiotics
- Long duration systemic antibiotics are sometimes needed until all lesions are gone, then given as daily prophylaxis for recurrent furuncles
Note: Abx therapy for months until all legions are gone.
Erysipelas: Characteristics
Refers to a streptococcal cellulitis, and is seems as a well demarcated area of violaceous erythema
Note: Cellulitis is a wastebasket diagnosis for any bacterial infection of the skin and skin structure, with or without abscess, appearing as erythema, warmth, and tenderness
How to differentiate erythema v. cellulitis
A good way to determine if cellulitis in an extremity is present, is to elevate the extremity above the heart to see if the erythema fades. If not, it’s likely cellulitis and not something else
Erysipelas: Tx
Systemic antibiotics suitable to treat Streptococcal spp are usually needed
Purpura fulminans: Characteristics
- A rare syndrome of intravascular thrombosis and hemorrhagic infarction of the skin.
- The cutaneous manifestation of meningcoccemia (meningococcal meningitis,
Purpura fulminans: S/Sx
Symptoms of meningitis (headache, neck stiffness) are usually present, plus hypotension, high fever, and altered mental status, all of which happen extremely rapidly
Purpura spread over hours.
Lyme Borreliosis (Lyme Dz): S/Sx
Erythema migrans (EM), which usually is accompanied by fatigue, myalgias/arthralgias, headache, about 7-28 days after infection. *EM does not necessarily appear at the site of the tick bite.
Lyme Borreliosis (Lyme Dz): Etiology
Borrelia burgdorferi is a spirochete that is transmitted from infected ticks (usually deer ticks) to people from a bite
Lyme Borreliosis (Lyme Dz): Ppx
If a tick is found on a person, the tick can be removed and a single dose of doxycycline 200mg orally can be given which is effective in preventing infection
Lyme Borreliosis (Lyme Dz): EM lesion characteristics
The EM lesion is a macule or papule which enlarges over days to form an expanding annular lesion with a distinct red border and partial cleaning in the middle, sometimes concentric annular lesions are present taking the appearance of a target. (i.e. bull’s eye)
Lyme Borreliosis (Lyme Dz): Tx
In uncomplicated cases, doxycycline 100mg PO bid for 14-21 days is usually effective
Human papilloma virus: Characteristics
- Causes warts which can be anywhere
- Extremely widespread and often require no treatment, but are simply a nuisance or aesthetically unpleasant
Human papilloma virus: DDx
On males, the differential diagnosis is pearly penile papules, which are harmless, but unusual looking
Human papilloma virus: Prognosis
Genital warts do increase the risk of certain invasive carcinomas, such as cervical or penile cancer
Molluscum Contagiosum: Characteristics
- Caused by Molluscum contagiosum virus (pox virus), and is a benign viral infection that is largely (if not exclusively) a disease of humans
- More common in children, but can be passed by sexual contact
Molluscum contagiosum: S/Sx
Skin-colored (or sometimes pearly white), non-tender papules which are umbilicated, often on the face, or in the groin
Molluscum contagiosum: Tx
- No treatment is needed, the condition usually resolves in a few months and cause no problems
- Advise Pts to avoid skin-to-skin contact with others during infection
- If the lesions are very troublesome, they can be cryodestroyed (Do not puncture lesions since they contain a lot of virus!)
Molluscum contagiosum: DDx
HPV, sabaceous cyst
Rubella: Characteristics
- Most adults are vaccinated against this, but occasional cases are still seen, also known as “three day measles” or “German measles”
- Generally mild illness
- Incubates 14-21 days
Rubella: S/Sx
- Begins with petechiae on the soft palate
- Then, erythematous, maculopapular rash on the face
- There is development of low grade fevers, fatigue, aches/pains and some congestion
- Next, these spread to the trunk and extremities
- Usually about 48 hours after the facial lesions appear, they fade
Rubella: Tx
- Treatment is supportive, but it can progress to an encephalitis or cause cataract development in children
- The rash usually completely resolves in 3 days without any residual marks
Measles: Characteristics
- Also known as “Rubeola”
- Increasing incidence of outbreaks due to the misguided actions of so-called “antivaxxers”
- Remains endemic in Africa, where immunization campaigns are reducing its prevalence
- Generally a severe illness
- Has a predictable timeline to the illness, and is extremely contagious
Measles: S/Sx
- The rash is similar to rubella (erythematous macules/papules), but is intensely pruritic, more severe and becomes confluent, especially on the chest
- The rash is accompanied by a hacking, barking cough (the virus is spread by aerosol)
Measles: Tx
Most people clear the infection with supportive care, but it has a high rate of complications, specifically encephalitis which is often fatal
Measles: Timeline
- Any body fluid contains high viral load, and the infected person is infectious for about 4 days even before any symptoms are evident
- The timeline of measles has a mnemonic:
“4 D’s” The 4 day fever
“3 C’s” Cough, Coryza, Conjunctivitis - Uncomplicated measles, from late prodrome to resolution of fever and rash, lasts 7-10 days
- Cough may be the final symptom to appear
Measles: Dx
Koplik’s spots (white dots appears on inner cheek) are considered diagnostic of measles, however a NAAT test is available as confirmation
Measles: Prognosis
- Measles infection causes myelosuppression and secondary opportunistic infection is another way the disease can be fatal
- Exposure to measles virus in utero can cause multiple congenital defects
Hand-foot-and-mouth (HFMD) Dz: Characteristics
- Systemic infection caused by coxsakie virus
- Very contagious, spread by fecal-oral or oral-oral route
- Generally a mild illness that is self-limiting and requires no specific treatment
HFMD: S/Sx
Characterized by ulcerative oral lesions and a vesicular exanthem on the distal extremities in association with mild constitutional symptoms
Vaginal or sometimes perianal ulcerations are present
HFMD: Skin Lesions characters
- Skin lesions begin as 2-8mm macule or papule that quickly evolve to vesicles, lesions on the palm and soles usually do not rupture, but others can and form erosions with crusts
HFMD: DDx
Herpangina
HFMD: Mucosal lesions characters
- Mucosal lesions 5-10mm, small, punched out painful ulcers preceded by macule that form a grayish vesicle, common on the palate, the buccal mucosa and the tongue
