Infections/Parasites

Infections/Parasites-

-Lice-

-two types of lice that are obligate parasites in humans:  pediculus humanus and phithirius pubis
-commonly spread by direct contact between individuals or indirectly by contact with bedding, brushes or clothing.
-body lice is associated with poor socioeconomic conditions
-pubic lice is typically transmitted sexually
-pubic lice may not be transmitted sexually also.  Transmitted from pubic lice in hair on head and back
-itches and excoriations can get infected.
-Pediculosis Capitis-lice infection of the scalp
-Pediculosis Pubis-pubic lice
-Treatment avoid contact with contaminated items, environment should be vacuumed.  Permethrin, Malathion, Lindane


-Scabies-

-caused by Sarcoptes scabei
-hypersensitivity reaction of both immediate and delayed types occur in the development of lesions other than burrows
-persons with their first infection, sensitization takes several weeks to develop.  If it is a re-infection, itching may occur within twenty four hours
-lestions usually prefer the webspace and spare the head and neck
-Treatment-Permetherin 5% cream, Lindane


-Spider Bites-

-can easily be confused with a MRSA infection
-most spiders are harmless except brown recluse spider and the black widow spider
-can cause rashes from mild urticaria to full blown necrosis
-the black widow spider venom has a neurotoxin producing reactions at the bite site to varying degrees of systemic reactions
-mild rash locally is usually a maculopapular exanthem
-systemic reactions may cause fever, headache, arthralgias, nausea, and vomiting
-most are sensitive to bactrim or doxycycline (cover for MRSA)

Verrucous Lesions

Verrucous Lesions

-Actinic Keratosis-

-Single or multiple discrete dry rough, adherent scaly lesions on sun exposed areas.
-Occurs in adults
-Treatment is removal.  5 FU ointment also helpful.


-Seborrheic Keratosis:

-Usually see after the age of 30
-Early Stages-barely elevated papule
-Treatment is removal if patient is bothered by them

Acneiform Lesions

Acneiform Lesions-

-Acne Vulgaris-

-results from a change in keratinization pattern in the hair follicle.  The secretion of sebum is then blocked
-lesions are complex interaction between hormones and bacteria
-When the follicle has a portal of entry at the skin a semisolid mass protrudes and this is called a blackhead
-Prefers sites of face, neck, upper arms, trunks and buttocks
-Mild acne-topical antibiotics (Clindamycin), Benzoyl Peroxide, and Topical Retinoids (Tretinoin)
-Moderate Acne-oral antibiotics (Minocycline) is added to above it treatment fails.  Females can add high does of estrogens
-Severe acne-isotretinoin inhibits sebaceous gland function and keratinization


-Rosacea-

-patients usually have a long history of reddening of the face with increases of temperature in response to heat stimuli in the mouth
-Exposure to heat may cause exacerbations
-Acne may precede the onset of rosacea

-Stage I-Persistent erythema with telangiectases
-Stage II-Persistent erythema with telangiectases, papules and tiny pustules
-Stage III-Persistent deep erythema, dense telangiectases, papules, pustules, nodules, and solid edema

-Treatment-
-Topical metronidazole gel or cream.  Sodium Sulfacetamide.  Topical erythromycin
-Systemic-Tetracycline or minocycline
-oral isotretinoin maybe helpful for refractory cases

Vesicular Bullae

Vesicular Bullae-

-Bullous Pemphigoid-

-comes from interaction of the autoantibody with bullous pemphigoid antigen on the surface of the keratinocytes
-Bullous lesion comes from multiple molecules released from mast cells and eosinophils
-prefers the axillae, medial aspects of the thighs, groin, abdomen, arms and legs (flexor surfaces)
-Diagnosis is made by skin biopsy
-Treatment-Prednisone 50-100 mg daily until clear combined with azathoprine 150 mg daily
-Tetracycline have been effective in some cases

Desquamtion

Desquamation-

-Erythema Multiforme-

-Etiology
-Infection (HSV most common) and mycoplasma
-Drugs (PCN, Sulfonamides, Dilantin, and Allopurinol)
-Connective tissue disease
-Physical agents
-Pregnancy
-Malignancy
-Idiopathic is actually the most common etiology

-Target shaped lesions are classic
-Lesions are most common on the face and extremities

-Ranges from mild (EM minor) to severe (EM major)
-Minor-little or no mucus membrane involvement, vesicles but no systemic symptoms.  Likes extensor surfaces of extremities with target shaped lesions
-Erythema Multiform Major-most commonly from a drug reaction.  Has mucus membrane involvement, tendency for lesions to become confluent and bullous, fever, may have conjunctivitis, and ulcerations in larynx and trachea.
-Maximal Variant-lifethreatening


-Stevens-Johnson Syndrome-

-Consider a severe form of erythema Multiforme
-Lesions are more diffuse
-10% or less epidermal detachment
-Effects the mucus membranes (eyes, mouth, genitalia)
-Most often seen in children and young adults
-Usually preceded by URI symptoms
-Etiologies-
-50% are associated with drug exposure (sulfa, allopurinol, carbamazepine, penicillins, cephalosporins, vancomycin, rifampin, ibuprofen, naproxen, and fluoroquinolones.  Etiologies in not clear)
-chemicals
-infections- mycoplasma, viral infections, and immunizations
-Definitive diagnosis is skin biopsy
-Management-admit to burn center and ICU, IV Fluid replacement, Parkland Formula, Corticosteroids may or not be helpful, immunoglobulins, deride necrotic skin

-Toxic Epidermal Necrolysis (TEN)-

-Full thickness loss of epidermis
-Usually greater than 30% of body surface are and dermal detachment 
-Tends to involve mucus membranes
-Patients should be in a burn unit
-Risk of infection
-Electrolyte disturbance
-Fatalities are common
-80% of cases related to medication however 5% report no med use
-Chemicals can cause
-Also infections mycoplasma, viral infections and immunizations
-Management-admit to burn center and ICU, IV Fluid replacement, Parkland Formula, Corticosteroids may or not be helpful, immunoglobulins, deride necrotic skin

Papulosquamous Diseases

Papulosquamous Diseases-

-Drug Eruptions-

-Exact mechanism is unknown but likely a delayed hypersensitivity reaction
-In a previously sensitized patient, eruption starts within 2-3 days of given the drug
-Peak incidence is approximately 9 days after administration of the medication
-Very pruritic lesions and painful
-Macules and papules on lower legs and may progress to the whole body
-Lesions are bright red color
-Meds that can cause:  penicillins, sulfa, NSAIDS, Barbiturates, Nitrofurantoin, Isoniazid, Benzodiazepines, Phenothiazines, Carbamazepine, Allopurinol, Gold Salts
-Need to stop the medication
-Oral antihistamines
-Oral or IV Glucocorticoids
-Potent Topic Glucocorticoids can help prevent the spread of the rash
-Label patient as allergic to that medication and or class of medications


-Lichen Planus-

-idiopathic in most cases
-Also caused by drugs (gold), or infection (HCV) results in cell mediated immunity
-Lesions last months to years
-The 5 P’s of Lichen Planus-
-Purple
-Polygonal
-Papules
-Pruritic
-Planar

-Topical corticosteroids or intra-lesional injection with triamcinolone
-Cyclosporin mouth wash may be helpful for those with oral lesions
-Systemic corticosteroids or cyclosporin for severe cases
-Systemic retinoids & PUVA if needed


-Pityriasis Rosea-

-Herald patch precedes the exanthem phase
-Fine papules and plaques dull tawny oval exanthem that are scattered
-Christmas tree pattern
-Etiology unknown but Herpes 7 is suspected
-May last 6-12 weeks
-Oral antihistamines and topical glucocorticoids
-Short course of glucocorticoids may help


-Psoriasis-

-there is an overproduction of epidermal cells by 28 times normal
-Salmon pink papules and plaques sharply marginated with silvery scale
-Can be bilateral and symmetrical
-Psoriatic arthritis incidence 5-8%
-Topical treatment with fluorinated glucocorticoids in ointment base
-Small plaques triamcinolone aqueous suspension
-Vitamin D Analogues
-Topical retinoid Tazarotene
-When there is >10% TBSA PUVA or UVB therapy is indicated
-Scalp-Clobetasol lotion
-Methotrexate for more severe cases and cyclosporin or immune modulators

Eczematous Eruptions

Eczematous Eruptions-

-Contact Dermatitis-

-delayed hypersensitivity reaction

-well demarcated plaques of erythema and edema

-may have some vesicles (acutely)

-Subacute/Chronic-may have some plaques of erythema, dry scales, or desquamation 

-May have plaques of lichenification 

-Treatment-to remove offending agent if able to isolate

-Topical steroids in mild cases

-Severe cases may require systemic corticosteroids for 2 weeks (tapered)

-Burrows solution on wet dressing may be helpful

-Atopic Dermatitis-

-Type I Hypersensitivity reaction

-Lesions may be present for months to years

-Poorly defined erythematous patches

-Chronically the lesions may have some lichenification with excoriation marks

-Fissured areas with painful areas are possible

-May have associated allergic rhinitis or asthma

-Topical anti itch lotions are helpful

-Patients may need low potency steroid ointment at times

-Wet dressings

-UVA and UVB light may be helpful for chronic and subacute

-Dyshidrosis-

-sweating does not play a role

-rash presents as vesicles in clusters in early phases

-later phases scaling and painful fissures and crusting

-80% on hands and feet

-Treatment involves high potency topical glucocorticoids for 1-2 weeks

-Burrow’s solution maybe helpful with wet dressings in early stages

-For severe cases systemic glucocorticoids is necessary over 1-2 weeks (tapered)

-Lichen Simplex Chronicus-

-Predilection of the skin that responds to trauma by epidermal hyperplasia

-Skin becomes hypersensitive and nerves and epidermis proliferate

-Itches

-Solid plaque of of lichenification from a confluence of small papules

-Scaling is minimal

-Skin feels thickened

-Areas of distribution scalp, ankles, lower thighs, exterior forearms, vulva, neck , scrotum and groin

-Occlusive dressings are helpful

-Can inject with triamcinolone 

-Combination of crude tar in zinc oxide and topical glucocorticoids is helpful