Scabies - Dx and Rx

Pathogenesis
infestation --> immune system sensitised to mite and mite-related products incl eggs
--> symptoms appear

Mite count usually 10-15, but can reach thousands in Norwegian (Crusted) Scabies

Dx
clinical
v itchy
bilateral
wrists, ankles, groin/genitals/buttocks, waist etc
often no burrows to see, especially in warm climate

Rx
2 Rx, one week apart
topical
"Lyclear" (permethrin cream)
OK from 2 months old but must be > 15 kg
Head-to-toe at bedtime. Wash off in the morning.
oral
ivermectin ("Stromectol")
150-200 mcg per kg
100kg = 15 - 20 mg
=> 5 or 7 tablets (each 3mg)
"Ready-reckoner" -  adults 15 mg; children 6 mg

Hot wash bed linen, towels, clothing
Rx family and close contacts
(significant incidence of asymptomatic cases => carriers)

Pets don't harbour human mites
=> can't give you scabies; no need to Rx

Response to Rx usually within 3 days (most resolved in 2 weeks), 
but pruritus can remain for up to 2 months

Dx Tinea (corporis) vs Granuloma Annulare

Tinea => border is scaly


Granuloma Annulare => border is non-scaly

Dx Acne Vulgaris vs Acne Rosacea

Vulgaris => comedones (keratin plugs in pilosebaceous unit) - white or black (if oxidised)


Rosacea => no comedones


NB:
Important DDx of (white heads) comedones = Milia  |  Usually found in infra-orbital/cheek regions

Milia = keratin "bleb" vs keratin "plug" in vulgaris (forming a comedone)

Parapsoriasis - What Is It?

A continuum is thought to exist: 

Chronic dermatitis ---> Parapsoriasis ---> T cell lymphoma (mycosis fungoides)

Parapsoriasis may be defined thus

1. Plaque-type (usually elderly and on legs; circinate patches may be red, yellow, brown, pink; plaques tend to be thin)

    (sometimes called chronic scaly superficial dermatitis)

.. Small plaque

.. Large plaque

2. Lichenoid

.. Pityriasis lichenoides

.... acute

.... chronic

Most cases aren't painful or itchy

If this is part of DDx -> consider punch biopsies to exclude a T cell lymphoma

Else histology changes tend to be non-specific

Emollients very important to hydrate skin

Otherwise,Rx tends to be that for dermatitis, including topical c.steroids and UV therapy

Always a good reference site, I find ...

Parapsoriasis - Medscape Reference

emedicine.medscape.com/article/1107425-overviewApr 19, 2013 - Parapsoriasis describes a group of cutaneous diseases that can be characterized by scaly patches or slightly elevated papules


DDx includes
- dermatitis (particularly circinate/nummular type)
- psoriasis (plaque or guttate form)
- T cell lymphoma (mycosis fungoides)
- Pityriasis rosea
- Syphylis (secondary)

--> biopsies

--> ?syphylis serology

Skin Grafts

Two Broad Types

1. Full thickness
= epidermis + dermis (all of it)
Note!
Don't include fat

2. Partial ("split") thickness
= epidermis + part of dermis
And, again: no fat!

Skin Closure after Surgical Excision of Skin Lesion

Techniques to consider in order of preference (a guide only):
Most common technique
= primary closure
[Don't forget secondary closure - not 2nd on list, but not to be forgotten]
Then
- skin graft (split/not full thickness)
Flaps
- advancement
- rotational
- transformational
Finally
- skin graft (full thickness)

Dry Skin May Only Require Hydration with Emollients rather than Topical C.steroids

Dry skin is not necessarily inflamed

Emollients (good [greasy] ones) are essential and may be all that is required

However, [appropriately potent] topical c.steroid should be available