The following topics are discussed in this Tutorial.
White spots DD, Bites, Lymphedema DD, Pigmentation, Molluscum bodies, Bywaters lesions, Subcorneal pustular dermatosis, Ehlers Danlos,Sclerodermoid changes, Sinuses, Verrucous elbows,
Differential Diagnosis of White Spots
The mnemonic for congenital causes is WANT A DIP (of COLOUR) and then SIGN DIP. Remember albopapuloid epidermolysis bullosa, Degos disease, lichen sclerosis et atrophicus, halo nevi, vitiligo, anetoderma, follicular atrophoderma, idiopathic guttate hypomelanosis and drugs. Try searching in GSA under hypopigmentation
The image below is extragenital lichen sclerosus
Bites
Caterpillars tend to give lots of lesions, they are grouped and there may be associated urticaria. Ticks give few lesions, nodules with necrotic centres. Spiders tend to give few lesions, with pain, induration and necrosis. Bird mites are often on the top of the body and look for a central punctum. The Centipede has a single bite like a spider. Scabies gives multiple urticarial lesions sometimes with burrows particularly in the web spaces, axillae and groin and myiasis are found in a wound with maggots or as cutaneous myiasis presenting as boils with discharge or as a creeping eruption.
The image below is of a centipede bite
Pediculosis
Pediculosis capitis tends to present with an itchy scalp. Pediculosis corporis presents with urticarial bites and pediculosis pubis presents with eczema, infection and sometimes pigmentation.
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| Pediculosis pubis |
Differential Diagnosis of Lymphedema
There is primary and secondary lymphedema. The congenital type is due to hypoplasia or absence of lymphatic vessels. The acquired type can follow infection, tumour, irradiation, surgery, frostbite or worms.
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| Congenital lymphedema and secondary skin changes |
The mnemonic is DAMN ANNE. Non Addisonian pigmentation is DAMN standing for drugs, autoimmune, metabolic and nutritional. Addisonian pigmentation is ANNE standing for autoimmune, neoplastic, nutritional and endocrine.
Pigmented Spots in a White Area
Pigmented spots in a white area is due to vitiligo with repigmentation or piebaldism.
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| Piebaldism |
Blotchy Hypopigmentation of the Skin
Consider incontinentia pigmenti, post inflammatory hypopigmentation and pinta
The image below is post inflammatory hypopigmentation
Thickening of Folds
This is present in scleromyxedema, it is bound down in scleroderma and smoothed out in scleredema.
The Melkerson-Rosenthal syndrome is bilateral on the cheeks. The lips are always swollen top and bottom. It can occasionally be unilateral on the cheeks.
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| Melkerson Rosenthal syndrome Swollen lip red face |
Sycosis barbae tends to give a plaque type of erythema with deep inflammed follicles. It leaves scarring. In the lupoid form you tend to have active papules and pustules around a pink atrophic scar.
Hereditary Haemorrhagic Telangiectasia
In hereditary haemorrhagic telangiectasia the telangiectasia can be linear or punctate. Note the pulmonary arteriovenous anastamoses or shunts.
Molluscum Bodies
This is not a good term. It can be associated obviously with molluscum contagiosum but it is usually in association with neurofibromatosis although these lesions can also be seen in the Ehlers-Danlos syndrome and acrodermatitis chronica atrophicans.
Bywaters Lesions
Bywaters lesions( small ulcers on finger pulps) are seen in rheumatoid arthritis whereas Janeway lesions( non tender macules, papules or nodules present on the palms and soles) are seen in subacute bacterial endocarditis.
Types of Pustular Psoriasis Subcorneal pustular dermatosis has pustules at the edge, the mouth is not involved and neither are the nails. You can get it in the scalp. It is not painful. Watch for an IGA gammopathy and typically it will present with flaxid oval vesicles. Sometimes with a meniscus line in the pustule. Compare with pustular psoriasis of the Von Zumbusch’s type where the patient is toxic and the mouth and perioral areas and nails are all involved. There is a fiery red background and it is painful. Remember also the various localised types of pustular psoriasis including palmar plantar and acropustulosis of Hallopeau.
Leprosy Morphologies Macules are seen in all stages. Indeterminate is always and only macular. Borderline tuberculoid has a sharp inner edge to an annular lesion. Tuberculoid has a sharp outer edge. Borderline tuberculoid also has annular and has bands. Xanthomas Eruptive show an increase in triglycerides, xanthelasma shows an increase in cholesterol, tendinous show Type 2 lipids, tuberous Type 3 and palmar Type 2. Psoriatic Arthropathy It is usually distal, can be mutilating, its rheumatoid like, it is facetal in the spine and it can also be ankylosing spondylitis like. With spondylitis it is HLAB 27, in distal psoriatic arthropathy it is HLA B13, 17 and 37. The image below is of Tuberous Xanthomas  Ehlers-Danlos Syndrome There are nine types. One to three are autosomal dominant, four to eight are autosomal recessive but five and nine are x-linked recessive. The skin signs are an increase in elasticity with a soft velvety feel, joint hyper mobility, bruising, keloids and elastosis perforans serpiginosa. There may be pseudotumors and small nodules on the shins and the palms and soles may show very lax skin. Sclerodermoid Changes in the Lower Leg Seen in stasis, morphoea, scleroderma, Werner’s syndrome, scurvy, acrogeria and localised graft versus host. Also in lipodermatosclerosis. The Image below is Ehlers Danlos  Causes of Acanthosis Nigricans The mnemonic is BLACK SPOT. Blooms, Leske’s, Lawrence-Seip, ataxia telangiectasia, Cruzons disease, Sjogren Larsen, Prader-Willi, poly endocrine, Rudds and Downs Syndrome. Infected Lesions with Sinuses Conditions to consider include botryomycosis, scrofuloderma, others forms of TB, ischiorectal abscesses, amoebiasis, actinomycosis, Madura foot, osteomyelitis, lymphogranuloma venereum, pasturella multicida. Note a pyogenic granuloma like lesion on the cheek is a dental abscess. Verrucous Lesions on the Elbows These are seen as psoriasis, epidermal nevus, dermatomyositis, pityriasis rubra pilaris, lipoid proteinosis and epidermo dysplasia verruciformis. The image below is a montage of acanthosis nigricans  | |||
