Dermatology

Question 1

What is the cause of xeroderma pigmentosum?

Answer 1

Defective excision repair mechanism for UV damaged DNA (mutation in endonuclease), leads to formation of thymine dimers. Causes extreme sensitivity to light.

Question 2

Leser-Trelat Sign

Answer 2

Sudden appearance of multiple seborrheic keratoses. Indicates an underlying malignancy of the GI tract

Question 3

Which skin layer is affected in scalded skin syndrome? (s. aureus)

Answer 3

Stratum granulosum

Question 4

Which inflammatory dermatosis has a saw tooth appearance at the dermal-epidermal junction?

What virus can this be associated with?

Answer 4

Lichen Planus
Pruritic, purple, polygonal, planar, papules/plaques

Chronic Hep C infection

Question 5

Auspitz Sign

Answer 5

Seen in psoriasis
Pinpoint bleeding after picking off the silvery scale (due to elongated dermal papillae and thinning of epidermis above the papillae)

Question 6

What virus is associated with erythema multiforme

Answer 6

Herpes Simplex Virus

See targetoid lesions

Question 7

What virus is associated with molluscum contagiosum?

Answer 7

Poxvirus

See flesh colored papules that are umbilicated
On histo there are cytoplasmic inclusion bodies

Question 8

Lips and skin cancer

Answer 8

“This is a bunch of BS”
Upper lip: basal cell carcinoma (papule with teleangectasia and palisading)
Lower lip: squamous cell carcinoma (nonhealing ulcer, keratin pearls)

Question 9

Sturge Weber Disease

Answer 9

Port wine stain on face due to capillary malformations
Ipsilateral leptomeningeal angiomatosis (vascular malformations within the meninges)
Seizures

Question 10

Risk factors for SCC (different from BCC)

Answer 10

Arsenic exposure
Immunosuppressive therapy
Chronic inflammation

Question 11

What skin cancer is a patient on immunosuppressive therapy at risk for?

Answer 11

Squamous cell carcinoma

Question 12

What is chronic lymphedema a risk factor for?

Answer 12

Stewart Treves syndrome - development of cutaneous angiosarcomas

Question 13

What mutation is seen in melanoma? What other disorder is this mutation seen in?

Answer 13

Mutation in BRAF (protein kinase) causes proliferation of melanocytes.

Also seen in Hairy Cell Leukemia

Question 14

Cause of albinism

Answer 14

due to defect in tyrosine hydroxylase enzyme or tyrosine transport (tyrosine = aromatic amino acid)

Question 15

What skin disorder is associated with celiac disease?

Answer 15

Dermatitis herpetiformis

Pruritic blisters on extensor surfaces, IgA deposits, and microabscesses

Question 16

Birbeck granules

Answer 16

Seen in Langerhans cells:
dendritic cells of the skin derived from the myeloid cell line that have racquet-shaped intracytoplasmic granules called Birbeck granules

Question 17

Types of exocrine glands

Merocrine

Apocrine

Holocrine

Answer 17

Merocrine: cells secrete via exocytosis (ex. Apocrine/eccrine sweat glands, salivary glands)

Apocrine: cells secrete via membrane bound vesicles (ex. Mammary glands)
*vesicles look like apples (apples = breasts)

Holocrine: cell lysis releases entire contents of the cell (ex. Sebaceous glands, meibomian glands)
* release w”hol”e contents of cell

Question 18

What is the cause of male patterned baldness? How do you treat this?

Answer 18

Due to excess DHT (dihydrotestosterone)

Treatment is with 5a reductase inhibitors such as Finasteride to reduce the conversion of testosterone to DHT

Question 19

Neurofibromatosis Type 1 vs Type 2

Answer 19

Type 1: von Recklinghausen (chromosome 17, “17 letters in von Recklinghausen). Cafe au lait spots, cutaneous neurofibromas, pheos, Lisch nodule (pigmented iris hamartomas)

Type 2: (chromosome 22) Bilateral acousitc schwannomas, juvenile cataracts, meningiomas, ependymomas

Question 20

What is acanthosis nigricans associated with?

Answer 20

Insulin resistance

Malignancy (gastric carcinoma)

Question 21

Sandpaper rash

What causes this?

Answer 21

Scarlet fever

Erythrogenic toxin

Question 22

Vesicles in different states of healing

Answer 22

Varicella Zoster

Question 23

What type of collagen is secreted by the basal keratinocytes?

Answer 23

Type VII collagen

Question 24

Nikolsky sign

Answer 24

Separation of the epidermis upon manual stroking of the skin

Positive in pemphigus vulgaris (flaccid blisters)
Negative in bullous pemphigus (tense blisters)

Question 25

Destruction of desmosomes

Answer 25

Pemphigus vulgaris (fish net immunofluorescence) IgG

Question 26

Destruction of hemidesmosomes

Answer 26

Bullous Pemphigoid (immunofluorescence along basement membrane) IgG

Question 27

Patient presents with an ulcer above the medial malleolus and a hx of chronic LE edema

Answer 27

Stasis dermatitis (common complication of chronic lower edema secondary to venous stasis)

Question 28

Pellagra is due to what? | How does it present?

Answer 28

Niacin deficiency causing the 3 D's: Diarrhea Dementia Dermatitis *Niacin can be endogenously formed from tryptophan

Question 29

What cytokine is involved in normal wound healing?

Answer 29

TGF B Responsible for fibroblast migration, proliferation, and connective tissue synthesis

Question 30

Strawberry hemangioma

Answer 30

Appears in first few weeks of life -- will rapidly grow and then will spontaneously regress by age 5-8. DO NOT SURGICALLY REMOVE

Question 31

Xeroderma pigmentosum is caused by a defect in what enzyme?

Answer 31

Endonuclease

Question 32

Blueish tender lesion under fingernail

Answer 32

Glomus tumor -- arises from modified smooth muscle cells of the thermoregulatory glomus body

Question 33

Treatment of psoriasis

Answer 33

topical vitamin D analogs (Calcipotiene, calcitriol, and tacalcitol) bind to and activate the vitamin D receptor, a nuclear transcription factor that causes inhibition of keratinocyte proliferation and stimulation of keratinocyte differentiation Can also use TNF a inhibitors such as Enteracept or Infliximab

Question 34

What is thought to be the cause of atopic dermatitis (eczema) and what will labs show?

Answer 34

o Thought to be caused by mutations affecting filaggrin which causes impairment of the skin’s barrier function o High serum IgE, peripheral eosinophilia, and high levels of cAMP phosphodiesterase in their leukocytes o At risk of developing allergic rhinitis and asthma

Question 35

What skin layer is increased in psoriasis?

Answer 35

Stratum spinosum (Acanthosis)

Question 36

What cell layer has desmosomes?

Answer 36

Stratum spinosum

Question 37

What are liver angiosarcomas associated with?

Answer 37

Arsenic and vinyl chloride exposure

Question 38

Proteins that make up gap junctions? Function?

Answer 38

Connexins Intercellular communication

Question 39

Proteins that make up tight junctions? Function?

Answer 39

Claudins, occludin Paracellular barrier

Question 40

Proteins that make up adherens junctions? Function?

Answer 40

Cadherins Cellular anchor

Question 41

Proteins that make up desmosomes? Function?

Answer 41

Cadherins Cellular anchor

Question 42

Proteins that make up hemidesmosomes? Function?

Answer 42

Integrins Cellular anchor

Question 43

What happens when there is a defect in cadherin (e-cadherin)

Answer 43

Loss of E-cadherin promotes metastasis