dermatology Flashcards
How are the vesicles in herpes differentiated from incontinentia pigmenti?
Incontinentia pigments has vesicles in a linear pattern and without an erythematous base
What would be found on Wright stain in a patient with herpes simplex ?
Multinucleated giant cells and eosinophilic intranuclear inclusions
What diagnosis presents as multiple pustules on non erythematous base with vesicles and brown macules in a newborn?
Neonatal pustular Melanosis
What is seen on tzanck smear in a patient suspected of neonatal pustular melanosis?
Neutrophils
What diagnosis presents as yellow pustules on erythematous base and occasional vesicles in a newborn ?
Erythema toxicum
What is seen on tzanck smear in a patient with erythema toxicum?
Eosinophils with occasional neutrophils
When does erythema toxicum neonatorum typically appear? What parts of the body should be free of the rash?
Not present at birth but presents shortly after
Spares the palms and soles
What diagnosis presents as lichenification with scratching behind the knees and elbows ?
Atopic dermatitis
How can you differentiate tinea pedis from atopic dermatitis of the foot?
Tinea is scaling and peeling whereas atopic dermatitis is dry and scaly
Tinea spares the dorsal foot which would also be involved if atopic dermatitis
How would you treat eczema that is not improving with emollients and steroids?
Antibiotics against staph aureus
What foods should be eliminated in patients with atopic dermatitis ?
food elimination is not recommended
What diagnosis presents as acute eczema that is not responding to antibiotics and presents with vesicles and crusted erosions?
Eczema herpeticum
What diagnosis presents as greasy yellow patches on scalp, face and skin folds in the first 2 months of life?
Seborrheic dermatitis
What is the appropriate treatment for seborrheic dermatitis ?
Topical antifungal or topical steroids
What diagnosis presents with lesions similar to seborrheic dermatitis with ear discharge and increased urine output ?
Histiocytosis x
What type of hypersensitivity reaction (types 1-4) is poison ivy? How can a rash be prevented after exposure?
Type 4
Washing with soap and water & removing infected clothes
What type of desensitization treatment can be used against poison ivy rash?
None
What diagnosis presents as red plaques with thick scales on the elbows or knees with pinpoint bleeding? What are these bleeding spots called?
Psoriasis
Auspitz sign
What diagnosis presents as small oval scaling plaques that are thick and parallel to the lines of skin stress?
Pityriasis rosea
What is the treatment for pityriasis rosea?
Exposure to sun
What diagnosis presents as dry skin with thin scales and a pasted on appearance?
Ichthyosis vulgaris
What are the 3 treatment options for ichthyosis vulgaris?
Keratolytic agents (ammonium lactate)
Alpha hydroxy acid
Urea containing emollients
How can you distinguish tinea corporis from granuloma annulare?
Annulare is not scaly but tinea is
What is the infectious agent to consider in a patient with a chronic painful papular lesion on the sole of the foot after swimming ?
Atypical mycobacterium
What treatment should you use in an 8 year old female with an itchy rash on the soles of her feet with minimal scaling with spares the interdigital skin, thickened skin and hyperlinearity of the soles?
Triamcinolone cream (Rx for juvenile plantar dermatosis)
What is the cause of granuloma annulare?
Cause unknown - it is a benign inflammatory condition without epidermal involvement
How can you confirm diagnosis of either Ssss or TEN?
Skin biopsy
How can you differentiate TEN from SSSS based on clinical exam?
SSSS is superficial and exfoliated skin will not be red whereas TEN is full thickness involvement and red
What diagnosis would you consider in a well-appearing child with maculopapular rash with central clearing of some lesions and a few lesions on the mouth ?
Erythema multiform minor (not Stephens Johnson because child is well appearing)
What diagnosis should you consider in a patient with fever and rash as well as hypotension ?
Toxic shock syndrome
What presents as boggy blue ulcers with a necrotic base?
Pyoderma gangrenosum
What diagnosis presents as linear erythematous papules on the wrists, Scilla and groin? What is the treatment?
Scabies - permethrin
What is the treatment for head lice?
Permethrin cream (repeat in one week) in all household members or malathion
What should you do if a patient diagnosed with lice continues itching after treatment with premethrin?
Steroid cream - this is an inflammatory reaction and does not indicate treatment failure
What diagnosis presents with blue-gray macules on abdomen and inner thigh?
Pubic lice (crabs)
How long can Pubic lice last without a blood meal? How long can fresh eggs last on the hair shaft before hatching ?
36 hours without a blood meal
10 days until eggs hatch
What are the 2 first line treatment options for pubic lice?
Permethrin or pyrethrin
What are two alternative Pubic lice treatments and why are they not first line choices?
Malathion (flammable and irritating)
Lindane (neurotoxicity)
What is the treatment of pubic lice on the eyelashes ?
Petroleum jelly TID x 10 days
What is the diagnosis in a toddler with 2 months of recurrent pruritic rash of clustered red papules that tend to erupt at night. No one else in the family has a similar rash.
Popular urticaria
What is the appropriate treatment for popular urticaria?
Eliminate causative agent (ex. bug bite)
What diagnosis should you consider in a child with perioral dermatitis with alopecia and poor growth ?
Acrodermatitia enteropathica (zinc deficiency)
What is the inheritance pattern of acrodermatitis enteropathica?
Autosomal recessive
How can you differentiate zinc deficiency from biotin deficiency?
Biotin deficiency also has oral rash and alopecia but also presents with ataxia
What are closed comedones?
Whiteheads - follicles that are plugged but covered with epithelium
What are open comedones?
Blackheads - plugged follicles with no epithelial covering (black color is due to melanin NOT dirt)
What should you do in a 7 y/o patient who presents with acne? Why?
This could be a sign of precocious puberty and needs to be worked up
What are the 4 stages of acne development ?
Abnormal follicle keratinization
Excessive sebum production
Bacterial proliferation
Inflammation
What is the cause of excessive sebum production?
Androgen production
What are the 2 main types of acne ?
Inflammatory and noninflammatory
What is the cause of inflammation in a patient with acne?
Bacteria triggers the complement pathway
What may be the diagnosis in a patient with “acne” that is resistant to treatment? Exam shows red papules on the nose and cheeks
Adenoma sebaceum (angiofibromas)
What are two medications that may lead to acne?
Steroids and anticonvulsants
What are 4 main topicals used for acne and how do they work?
Benzoyl peroxide - bacteriocidal
Clinda / erythromycin - bacteriocidal and anti-inflammatory
Azelaic acid - for post inflammatory hyperpigmentation
Tretinoin - vitamin A derivative that prevents acne by halting hair follicle plugging
What would be the indication to use PO antibiotics for acne?
Severe inflammatory acne especially in trunk
What is the mechanism of action of isotretinoin (accutane) in treatment of acne?
Antibacterial
Reduces sebum production
Anti inflammatory
What are side effects of isotretinoin use and what needs to be monitor before and during use?
Dry skin/nosebleeds/headache
Teratogenic - rule out pregnancy!
What diagnosis presents as black dots on the scalp (aka broken hairs) and tender boggy areas of induration (kerions)?
Tinea capitis
What is the gold standard of diagnosis and treatment for tinea capitis?
Fungal culture
Griseofulvin 6-12weeks (routine labs not indicated)
What 3 conditions should you consider in a patient who presents with alopecia totalis?
Nutritional deficiency
Hypothyroidism
Lupus or other chronic systemic illness
What is the cause of hair loss which presents with different lengths of hair shafts ?
Trichotillomania
What is the cause of sudden complete areas of hair loss in round patches but no inflammation on exam?
Telogen effluvium - triggered by stressful events
You are presented with a child with areas of complete hair loss and nail pitting in a patient who presents with her hair in braids, what is the diagnosis and treatment?
Alopecia areata - reassurance or corticosteroids
What diagnosis presents as pigmented lesions that turn into hives and develop into blisters with rubbing? What is that “sign” called?
Urticaria pigmentosa
Darien sign
What is the treatment/recommendations for patients with urticaria pigmentosa?
No treatment - avoid narcotics, NSAIDs and radiocontrast
What is the underlying problem in patients with xeroderma pigmentosa ? How is it inherited ?
Enzyme deficiency prevents UV damaged DNA repair leading to high rates of skin cancer
Autosomal recessive
What diagnosis should you consider in a patient with port wine stain on the face along the trigeminal nerve distribution who also has cognitive deficits and seizures? What test should be done ?
Sturge weber - MRI to find venous leptomeningeal angiomatosis (does not correlate to size of port wine stain)
Other than dermatological and neurological findings, what else is associated with sturge weber?
Glaucoma
What are the diagnostic criteria for neurofibromatosis type 1?
Two of the following: >6 cafe au lait spots (>5 mm) Lisch nodules Neurofibroma Optic nerve glioma Freckling (axillary/inguinal) Bony defects Family hx of NF1
What is the inheritance of neurofibromatosis type 1?
Autosomal dominant but 50% are spontaneous mutations in chromosome 17
What are the causes of HTN often seen in patients with neurofibromatosis type 1?
Pheochromocytoma or renal artery stenosis
How is neurofibromatosis type 2 different from type 1?
Presents with acoustic neuromas (schwannoma) which causes hearing loss or tinnitus
Also the defect is on chromosome 22 not 17
What are the criteria for diagnosis of tuberous sclerosis ?
Presence of 2 of the following: Ash leaf spots x 3 Periventricular tubers Sebaceous gland hyperplasia Shagreen patch Subungal fibrous Cardiac rhabdomyoma Retinal nodular hamartomas Renal angiomyolipoma
What is the typical progression of capillary hemangiomas?
Present at birth and gradually get larger but resolve by age 9
What is kasabach Merritt syndrome ?
Rapidly progressive hemangioma due to platelet sequestration causing low platelets
Which type of congenital Nevus is most likely to transform into a melanoma?
Giant congenital nevi
What virus causes erythema infectious and what’s another name for this disease?
Parvovirus - fifth disease
What is the cause of erythema chronicum migrans and what other 3 symptoms are commonly seen?
Lyme disease - carditis, arthritis and neuritis
What is the name of the rash associated with rheumatic fever?
Erythema marginatun
