Dermatology

Question 1

Pityriasis versicolor is caused by which organism?

Answer 1

Malassezia furfur

Features
• Most commonly affects trunk, neck or arms
• Patches may be hypopigmented, pink or brown (hence versicolor)
- May be more noticeable following a suntan
• Scale is common
• Mild pruritus

Tx topical ketoconazole

Question 2

Which ulcerating skin lesion is associated with UC?

Answer 2

Pyoderma gangrenosum is a rare, non-infectious, inflammatory disorder. It is an uncommon cause of very painful skin ulceration. It may affect any part of the skin, but the lower legs are the most common site.

Small red papule which later became a deep, red, necrotic ulcer with a violaceous border

Question 3

Most common causes of erythema multiforme?

Answer 3

Causes

viruses: herpes simplex virus (the most common cause)
idiopathic
bacteria:Mycoplasma,Streptococcus
drugs: penicillin, sulphonamides, carbamazepine, allopurinol, NSAIDs, oral contraceptive pill, nevirapine
connective tissue disease e.g. Systemic lupus erythematosus
sarcoidosis
malignancy

Question 4

Eczema herpeticum (EH) is a disseminated cutaneous infection with herpes simplex virus that develops in a patient with atopic dermatitis.

What are classic findings?

Answer 4

EH typically presents as a sudden onset eruption of monomorphic vesicles and “punched-out” erosions with hemorrhagic crusts over eczematous areas

Esp HSV1

Medical emergency; most cases require IV antivirals as systemic dissemination and viremia can occur especially in immunocompromised patients

Question 5

A 26-year-old woman presents with a recurrent, intensely itchy rash on the palms of her hands… On examination, there are bilateral vesicles on the palms and the sides of the fingers. The palms look dry with areas of skin peeling. The rest of her body is spared.

What is the most likely diagnosis?

Answer 5

Pompholyx eczema (also known as dyshidrotic eczema) is a type of vesicular hand dermatitis

Question 6

Most common form of melanoma in people with darker skin?

Answer 6

Acral lentiginous melanoma: Pigmentation of nail bed affecting proximal nail fold suggests melanoma (Hutchinson’s sign)

Question 7

Hypertrichosis vs. hirsutism

Answer 7

Question 8

What are 3 conditions associated with HLA DR3?

Answer 8

dermatitis herpetiformis
Sjogren’s syndrome
primary biliary cirrhosis

Question 9

Pityriasis rosea is associated with which viral infections?

Answer 9

Reactivation of herpesviruses 6 and 7
- Herald patch

Question 10

Percentage differentiating SJS vs. TEN?

Answer 10

SJS 10-30%
TEN >30%

Question 11

Lesions in tuberous sclerosis?

Answer 11

A: “Ash-leaf” hypopigmented macules (most common)
B: Shagreen patch
C: Periungual fibroma (Koenen tumor)

Question 12

Painless (usually solitary) genital ulcer with raised borders and regional inguinal lymphadenopathy makes you think?

Answer 12

Primary syphilis chancre
- Treat with ben pen

Question 13

Non-pruritic blistering in both skin and mucosa affecting mouth, nose, throat, eyes, and genitals makes you think?

Nikolsky (leaves red mark) and Asboe-Hansen positive

Answer 13

Pemphigus vulgaris
- IgG against desmoglein 1 and 3
- Treat with steroids +/- rituximab

Question 14

Bullous pemphigoid features

Answer 14

Question 15

An itchy rash which starts with an oval patch first makes you think?

Answer 15

Pityriasis rosea
- Herald patch