Cutaneous infection & infestation (2)

Question 1

Management of genital warts

Answer 1

• topical podophyllum or cryotherapy are commonly used as first-line treatments depending on the location and type of lesion. Multiple, non-keratinised warts are generally best treated with topical agents whereas solitary, keratinised warts respond better to cryotherapy
• imiquimod is a topical cream which is generally used second line
• genital warts are often resistant to treatment and recurrence is common although the majority of anogenital infections with HPV clear without intervention within 1-2 years

Question 2

Management of warts (in general)

Answer 2

• generally not treated
• may resolve in 2 years
• difficult to treat

*if very severe case → laser treatments (plastic surgeon)

Question 3

Spot diagnosis

Answer 3

Molluscum Contagiosum

Question 4

Molluscum contagiosum

• pathophysiology
• transmission
• epidemiology

Answer 4

Molluscum contagiosum

• a common skin infection
• caused by molluscum contagiosum virus (MCV), a member of the Poxviridae family
• transmission occurs directly by close personal contact, or indirectly via fomites (contaminated surfaces) such as shared towels and flannels
• the majority of cases occur in children (often in children with atopic eczema), with the maximum incidence in preschool children aged 1-4 years

Question 5

Features of molluscum contagiosum

Answer 5

• characteristic pinkish or pearly white papules with a central umbilication, which are up to 5 mm in diameter
• lesions appear in clusters in areas anywhere on the body (except the palms of the hands and the soles of the feet)
• in children, lesions are commonly seen on the trunk and in flexures, but anogenital lesions may also occur
• in adults, sexual contact may lead to lesions developing on the genitalia, pubis, thighs, and lower abdomen
• Rarely, lesions can occur on the oral mucosa and on the eyelids

Question 6

Self-care advice in molluscum contagiosum

Answer 6

Self care advice:

• molluscum contagiosum is a self-limiting condition
• Spontaneous resolution usually occurs within 18 months
• lesions are contagious, and it is sensible to avoid sharing towels, clothing, and baths with uninfected people (e.g. siblings)
• encourage people not to scratch the lesions. If it is problematic, consider treatment to alleviate the itch
• exclusion from school, gym, or swimming is not necessary

Question 7

Management of molluscum contagiosum

Answer 7

Treatment is not usually recommended.

If lesions are troublesome or considered unsightly, use simple trauma or cryotherapy, depending on the parents’ wishes and the child’s age:

• Squeezing (with fingernails) or piercing (orange stick) lesions may be tried, following a bath. Treatment should be limited to a few lesions at one time
• Cryotherapy may be used in older children or adults, if the healthcare professional is experienced in the procedure
• Eczema or inflammation can develop around lesions prior to resolution. Treatment may be required if:
• → Itching is problematic; prescribe an emollient and a mild topical corticosteroid (e.g. hydrocortisone 1%)
• → The skin looks infected (e.g. oedema, crusting); prescribe a topical antibiotic (e.g. fusidic acid 2%)

Question 8

Referral in molluscum contagiosum

Answer 8

Referral may be necessary in some circumstances:

• For people who are HIV-positive with extensive lesions urgent referral to a HIV specialist
• For people with eyelid-margin or ocular lesions and associated red eye urgent referral to an ophthalmologist
• Adults with anogenital lesions should be referred to genito-urinary medicine, for screening for other sexually transmitted infections

Question 9

Spot diagnosis

Answer 9

Ringworm → tinea corporis

Question 10

Tinea Corporis

• cause
• description
• treatment

Answer 10

• causes include Trichophyton rubrum and Trichophyton verrucosum (e.g. from contact with cattle)
• well-defined annular, erythematous lesions with pustules and papules
• may be treated with oral fluconazole

Question 11

(3) main types of infection with dermatophyte

Answer 11

Tinea is a term given to dermatophyte fungal infections

Three main types of infection are described depending on what part of the body is infected

• tinea capitis - scalp
• tinea corporis - trunk, legs or arms
• tinea pedis - feet

Question 12

Tinea capitis

• cause
• management

Answer 12

Tinea capitis (scalp ringworm)

• a cause of scarring alopecia mainly seen in children
• if untreated a raised, pustular, spongy/boggy mass called a kerion may form
• most common cause is Trichophyton tonsurans in the UK and the USA
• may also be caused by Microsporum canis acquired from cats or dogs
• diagnosis: lesions due to Microsporum canis green fluorescence under Wood’s lamp*. However the most useful investigation is scalp scrapings
• management: oral antifungals: terbinafine for Trichophyton tonsurans infections and griseofulvin for Microsporum infections. Topical ketoconazole shampoo should be given for the first two weeks to reduce transmission

Question 13

What’s that?

Answer 13

Tinea pedis (athlete’s foot)

• characterised by itchy, peeling skin between the toes
• common in adolescence

Question 14

Management of tinea pedis

Answer 14

• General measures should be first-line, including meticulous drying of feet, especially between the toes, avoidance of occlusive footwear, and the use of barrier protection (sandals) in communal facilities.
• Topical antifungal therapy once or twice daily is usually sufficient. These include azoles, allylamines, butenafine, ciclopirox, and tolnaftate. A typical course is 2 to 4 weeks, but single dose regimes can be successful for mild infection
• For those who do not respond to topical therapy, an oral antifungal agent may be needed for a few weeks. These include:
• Terbinafine
• Itraconazole
• Fluconazole
• Griseofulvin

Question 15

If we suspect fungal infection what are we going to do?

Answer 15

Skin scrappings → send to microbiology

Question 16

Do we need LFTs while using terbinafine?

Answer 16

• need for oral (not for topical)
• only if treatment for longer than 3 weeks

Question 17

Potential causes (infective agents) of fungal nail infections

Answer 17

Onychomycosis is fungal infection of the nails. This may be caused by:

• dermatophytes - mainly Trichophyton rubrum, accounts for 90% of cases
• yeasts - such as Candida
• non-dermatophyte moulds

Question 18

Risk factors for fungal nail infections

Answer 18

Risk factors include for fungal nail infections include diabetes mellitus and increasing age

Question 19

Features of nail fungal infection

Answer 19

• ‘unsightly’ nails are a common reason for presentation
• thickened, rough, opaque nails are the most common finding

Question 20

Investigations for nail fungal infections

Answer 20

• nail clippings
• scrapings of the affected nail
• the false-negative rate for cultures are around 30%, so repeat samples may need to be sent if the clinical suspicion is high

Question 21

Management of nail fungal infections

Answer 21

• do not need to be treated if it is asymptomatic and the patient is not bothered by the appearance
• diagnosis should be confirmed by microbiology before starting treatment
• dermatophyte infection:
  
  • oral terbinafine is currently recommended first-line with oral itraconazole as an alternative
  • 6 weeks - 3 months therapy is needed for fingernail infections whilst toenails should be treated for 3 - 6 months
  • treatment is successful in around 50-80% of people
• Candida infection:
  
  • mild disease should be treated with topical antifungals (e.g. Amorolfine) whilst more severe infections should be treated with oral itraconazole for a period of 12 weeks
• if topical treatment is given treatment should be continued for 6 months for fingernails and 9-12 months for toenails

Question 22

Pathophysiology of scabies

Answer 22

• Scabies is caused by the mite Sarcoptes scabiei and is spread by prolonged skin contact
• It typically affects children and young adults
• The scabies mite burrows into the skin, laying its eggs in the stratum corneum. The intense pruritus associated with scabies is due to a delayed-type IV hypersensitivity reaction to mites/eggs which occurs about 30 days after the initial infection

Question 23

Features of scabies

Answer 23

• widespread pruritus
• linear burrows on the side of fingers, interdigital webs and flexor aspects of the wrist
• in infants, the face and scalp may also be affected
• secondary features are seen due to scratching: excoriation, infection

Question 24

Management of scabies

Answer 24

• permethrin 5% is first-line
• malathion 0.5% is second-line
• pruritus persists for up to 4-6 weeks post eradication
• avoid close physical contact with others until treatment is complete
• all household and close physical contacts should be treated at the same time, even if asymptomatic
• launder, iron or tumble dry clothing, bedding, towels, etc., on the first day of treatment to kill off mites

Question 25

Advice on how to apply insecticides

Answer 25

The BNF advises to apply the insecticide to all areas, including the face and scalp, contrary to the manufacturer's recommendation. Patients should be given the following instructions: * apply the insecticide cream or liquid to cool, dry skin * pay close attention to areas between fingers and toes, under nails, armpit area, creases of the skin such as at the wrist and elbow * allow to dry and leave on the skin for 8-12 hours for permethrin, or for 24 hours for malathion, before washing off * reapply if insecticide is removed during the treatment period, e.g. If wash hands, change nappy, etc * repeat treatment 7 days later

Question 26

* Diagnosis * Management

Answer 26

***Crusted (Norwegian) scabies*** * Crusted scabies is seen in patients with suppressed immunity, especially HIV * The crusted skin will be teeming with hundreds of thousands of organisms ***Ivermectin*** is the treatment of choice and isolation is essential

Question 27

What's head lice? (pathophysiology)

Answer 27

**Head lice** (also known as pediculosis capitis or 'nits') * common condition in children caused by the parasitic insect *Pediculus capitis*, which lives on and among the hair of the scalp of humans * Head lice are small insects that live only on humans, they feed on our blood * Eggs are grey-brown and about the size of a pinhead. The eggs are glued to the hair, close to the scalp and hatch in 7 to 10 days * Nits are the empty eggshells and are white and shiny * They are found further along the hair shaft as they grow out

Question 28

The spread of head lice

Answer 28

Head lice * spread by direct head-to-head contact and therefore tend to be more common in children because they play closely together * they cannot jump, fly or swim! * when newly infected, cases have no symptoms but itching and scratching on the scalp occurs 2 to 3 weeks after infection * There is no incubation period

Question 29

Diagnosis of head lice

Answer 29

fine-toothed combing of wet or dry hair

Question 30

Management of head-lice

Answer 30

* treatment is only indicated if living lice are found * a choice of treatments should be offered - malathion, wet combing, dimeticone, isopropyl myristate and cyclomethicone * household contacts do not need to be treated unless they too are affected School exclusion is not advised for children with head lice