Papular, eczematous and pruritic eruptions

Question 1

Verruca vulgaris etiology

Answer 1

caused by HPV
transmitted by skin-to-skin contact
breaks in stratum corneum facilitate epidermal infection
Risk factors: immunocompromised, meat handlers

Question 2

Verruca vulgaris histology

Answer 2

papillomatosis (undulation of epidermis)
hyperkeratosis and parakeratosis
blood/serum in the stratum corneum
coarse keratohyaline granules
perinuclear vacuolation

Question 3

Verruca vulgaris clinical features

Answer 3

Firm hyperkeratotic papules with dull, clefted surface and vegetations
Red or brown dots caused by thrombosed capillary loops
Minimally elevated flat papules: verruca plana

Question 4

Molluscum Contagiosum etiology

Answer 4

caused by a pox virus
spread through skin to skin contact
common in children and HIV patients
also in genital areas of sexually active adults

Question 5

Molluscum Contagiosum clinical features

Answer 5

skin coloured umbilicated papules
central punctum/depression pearly appearance
Mollusca undergoing spontaneous regression may have an erythematous halo
Molluscum often have surrounding eczema

Question 6

Scabies etiology

Answer 6

hypersensitivity to mite (Sarcoptes scabiei)
can take 6 weeks from exposure to develop
Pruritus is often nocturnal
Spares head and neck except in infants and elderly
Spread through skin to skin contact and fomite

Question 7

Norwegian scabies

Answer 7

heavy infestation of scabies mite in immunocompromised hosts

Highly contagious and require repeated treatments

Question 8

Scabies clinical features

Answer 8

Widespread pruritic eczematous eruption
Burrows: serpiginous track with spot at end - scrape for diagnosis
Nodules: red-brown nodules in axillary area and groin which can persist after clearing infection

Question 9

Scabies Dx

Answer 9

Clinical: web space burrows and nodules in axillary and groin areas
Skin scraping: for confirmation. Place the dark spot at the end of the burrow on slide
Finding of mite confirms, finding of eggs/feces is suspicious
Skin biopsy can also be suggestive but can have very few mites on body

Question 10

Pediculosis corporis etiology

Answer 10

Louse infestation (pediculosis humanus humanus)
secondary infection common
Crowded conditions, poverty
Can transmit other infections: trench fever and epidemic typhus

Question 11

Pediculosis corporis clinical features

Answer 11

no primary lesions
secondary eczematous erruptions only
Look in seams of clothing for louse and nits

Question 12

Intertrigo

Answer 12

rash of body folds

Question 13

Tinea cruris etiology

Answer 13

caused by TInea rubrum and Tinea mentagrophytes

Risk factors: warm weather, obesity, tight clothing, topical steroid use, male, tinea pedis or tinea unguium

Question 14

Tinea cruris histology

Answer 14

hyperkeratosis and parakeratosis
numerous inflammatory cells in the dermis and epidermis
sparse fine branching hyphae

Question 15

Tinea cruris clinical features

Answer 15

well-marginated scaling red plaques with central clearing
papules and pustules may present at margins
occurs in inguinal region and on thighs

Question 16

Tinea cruris Dx

Answer 16

DDx erythrasma, inverse psoriasis, candida

Diagnosis by KOH showing hyphae and culture

Question 17

Candida intertrigo etiology

Answer 17

found in moist environment

risk factors: immunocompromised, topical steroids, diabetes

Question 18

Candida intertrigo clinical features

Answer 18

erythematous plaques with satellite papules and pustules

Question 19

Candida intertrigo Dx

Answer 19

DDx: contact dermatitis, seborrheic dermatitis, inverse psoriasis, dermatophyte infection
Dx: swab for gram stain and culture

Question 20

Erythrasma etiology

Answer 20

caused by Corneybacterium minutissimum

adults, humid weather, obesity, tight clothes

Question 21

Erythrasma clinical features

Answer 21

sharply marginated patch
no satellite papules/pustules
Body folds: toe web spaces, groin, axillae, intergluteal, inframammary

Question 22

Erythrasma diagnosis

Answer 22

coral red fluorescence on wood’s light, bacterial culture

absence of fungi on KOH