Dermatology Flashcards
Discuss a general approach to an unknown rash
1: time of onset
2) historical features
- new potential allergens
- change over time
- progression waxing or waning
- Associated symptoms - pain pruritis, fever, sexual history, occupation or hobbies
3) medical hisotry
4) primary lesions
5) secondary lesions
6) distribution of the lesions
7) systemic illness
8) diagnoistic tests
9) category of rash
- infectious
- immune
- vascular
- allergic
- malignancy
10) treatment
Differentiate primary and secondary lesions
Primary lesions arise as a direct result of the disease process
Secondary lesions aris from subsequent factros such as scratching, treatment, healing or complicating infection.
Describe primary lesions
1) Macule - flat circumscribed pigmented area <0.5cm
2) Patch - flat circumscribed pigmented area >0.5cm
3) Papule -elevated solid palpable lesion variable colour - <0.5cm
4) plaque - elevated solid palpable lesions variable colour > 0.5cm
5) Nodule - solid palpable subcutaneous lesions <0.5cm in diameter
6) tumor - solid palpable subcutaneous lesiosn >0.5cm
7) vesicle elevated thin walled circumscribed clear fluid filled lesion <0.5cm in diamter
8) Pustule elevated circumscribed purulent fluid filled lesion
9) Petechia - flat eryhtematous or violaceous non blanching lesios <0.5cm in diamter
10) purpura - erythemaotus or violaceous non blanching leiosns may be palpable >0.5cm
Describe secondary lesions
1) Scale - thickened area of keratinized epithelium
2) Crust -dried area of plasma proteins resulting from inflamation
3) fissures - deep cracks in the skin surface extending into the dermis
4) Erosions - disruption of surface eiptherlium usually linear traumatic
5) ulcer deep erosion extending into dermis
7) scar dense collection of collagen
8) excoriation: linear erosions typically secondary to scratching or rubbing
9) Lichenification - abnormally dense layer of keratinzed epidermal cells
10) hyperpigmentation
Describe tinea corporis
Refers to superficial dermatophytic infection of the skin and or nails usually by the trichophyton organism.
Commonly referred to as ringworm infection presents as a sharply marginated annular lesion with raised or vesicular margins and central clearing
Usually respond well to topical antifungal creams such as clotrimazole
Ketoconazole 2% cream applied once dailey
Miconazole 2% cream twice dailey for 4 weeks
Describe tinea capitus
Fungal infection of the scalp. Although it is often seen in paediatric patients 6-10 years old tinea capitus is also seen in adults
Alopecia may be seen typically with thickned scaly scalp. Broken hairs resembling black dots near the saclp may be seen
May be transmitted by close child to child contact and contact with household pets hats, combs barber shears and similar items
Systemic therapy is required for tinea capitus due to fungal invasion of the hair follice.
Oral terbinafine 250mg orally OD for 4 weeks
-20-40 kg 125mg
>20kg -62.5mg
Describe Kerion
A kerion is a fungal infection affecting hair follicles that is characterized by intense inflammation and a boggy erythematous mass typically affecting the scalp
Most common in children and in African AMericans- local alopecia and scarring can ensure
Kerions are terated the same as tinea capitus with systemic antifungals agents for 6-8 weeks. If abcterial superinfection exists an antibiotic is added. Clinda if MRSA or Bactrim
Surgical drainage of Kerions are not helpful and should be avoided
Describe tinea unguium
Oncyomycosis
- loosening of the nail plate form the nail bed
- yellow discolouration of the nale
Describe tinea cruris
Groin and gluteal celft
Describe oral candidiasis
Most common climical expression of candida. It is common in newborns, elder persons, immunosuppressed or persons wearing dentures.
It appears as patches of white or gray friable material covering an erythematous base on the buccal mucosa gingiva toungue palate or tonsils.
DDX of candidiasis include lichen planus (which unlike candida is not easily scraped off) or hairly leukoplakia
Oral mucous membrane infection is an AIDS defining illness
Treatment for oral candidiasis may be undertaken with topical antifungal agents
-nystatin liquid 100000 units/ml 1ml topically than swallowed QID after feeding for 7-14 days
Oesophageal candidiasis will require systemic treatment
-fluconazole 200mg for first dose than 100mg dailey for 14-21 days
Discuss treatment of vulvovaginal candidiasis
Topical clotrimazole 1% vaginal cream once dailey at bedtime for 6 nights
or if not tolerating topical
One dose of fluconazole 150mg orally as a single dose
Discuss scabies infestations
Scabies mites can live off the human host for 3 days
Scabies present with intense pruritus and rash which usually develop after 1-8 weeks following exposure. Typically it is worst at night.
Clinical findings incldue small papules or pustules and small raised or flattened burrows. Distributed between the digital webs side of the fingers and volar aspects of the wrist and alteral palms, trunk elbows axillae scrotum penis and the areola in women.
In crusted sabies hyperkaratotic plaques develop diffusely often on the plamar and plantar regions. Immunodeficient patients are at risk for crusted scabies.
First line treatment of scabies is topical permethrin 5% – applied from the neck down covering all areas of the body including under the nails in the umbilicus around teh nipple and genitals. Face and scalp should be treated in infants and young children. Preferably it should be applied prior to bedtime left on overnight and then washed off 8-12 hours later. A second treatment should be administered in 1-2 weeks..
Equally important in the treatment is the decontamination of the clothing bed lines and towels by washing them in hot water and hot machine drying.
Permethrin 1% is also affective for headlice and genital lice
Discuss dermatitis
Inflammatory reaction of the skin to a chemical physical or biological agent which acts as an irritant or allergic sensitizer
Allergic contact dermatitis is a form of delayed hypersensitivty mediated by lymphocytes sensitized by the contact of the allergen to the skin. It is much less common than irritant contact
THe primary lesions of contact dermaitits are papules, vesciles and bullae on an erythematous base. Streaky linear intensely pruritic lesions are characteristic. Normally in a pattern in the region in contact with the allergne.
Treatment include avoidance of the irritant or allergen and treatment of inflammation. Low potency topical steroid creams may be applied to erythematous areas around natural orifices and medium potency can be used elsewhere.
Describe drug reactions
The most common eruptions are a morbilliform rash, urticaria, or fixed drug eruptions. More severe reaction may include vasculitis, erythema nodosum, angiooedema anaphylasis, stevens jhonson syndrome TEN, blistering dermatosis, drug induced lupus
Drug reactions often appear within 4-21 days after the drug is taken. Skin lesions may appear after a drug has been discontinued and may rowsen if the drug or metbaolite persist in the system.
Fixed drug reactions appear and recur at the same anatomic site after repeated exposure to the same drug
Treatment of drug eruptions beings with discontinuation of the inciting agent - most will fade wihtin 1 week of discontinuation, Antihistamines and steroids may be indicated.
Define morbilliform
The term morbilliform means measles-like because of the development of a maculopapular erythematous rash that becomes confluent
Discuss Atopic dermatitis
Eczema Atopic dermatits is an inflammatory skin condition. Diagnostic criteria include itchy skin plus three or more of the following -History of flexure involvement -generalised dry skin in the past year -histroy of asthma or hay fever -onset of rash before 2 years old -flexural dermatitis
Skin lesions generally appear as inflammatory thickened papular or papulovesicular lesions. The skin is typically dry and may b e scaly but in its acute phase may also be vesicular weeping or oozing.
Most common in antecubital or popliteal flexion areas, neck face and chest.
Intence pruritus is a hallmark of atopic dermaitits. During flares itch and failure of routine treatments are common presentation. Patients may also present with secondary infections. Repeated rubbing and scratching produce lichenifications.
Topical steroids are the cornerstone of therapy and are often best prescribed in ointment form. Approximately 80% of patients have improvement of symptoms with topical steroid treatment.
Skin dryness can be treated with lubricating ointments such as vaseline
Discuss disposition for eczema patients
Inpatient admission should be considered for those with generalized erythema and exfoliation or intractable itching in that skin breakdown and sever secondary abcterail or viral skin infections.
Patients with atopic dermatitis are suscepetiable to infection and colinization by a variety of organisms due to defective skin barrier and fucntion. Wide spread disseminated viral infections such as escema molluscum, vaccinatum or herpticum and recureent staph pustolosis are especially concerning and should be treated with antiinfectives as needed.
