Topics discussed in this Tutorial
Squamous diseases DD, Purpuric blisters, Intertrigo non healing, Earlobe infiltrates, Interesting Slides, Papules Acral, Penile plaques, Vegetating lesions dd, Desquamation, Angular cheilitis, Ear fissures, Seborrhoeic dermatitis, Photosensitivity,
The next few sections will cover the differential diagnosis of squamous disorders, of purpuric blisters and axillary erythematous squamous rashes.
The Differential Diagnosis of Squamous Diseases
The three Ps, the three Ls and the keratoses. The three Ps are psoriasis, the pityriasis types and post inflammatory. The three Ls are lichen planus, lupus and the loose epidermis of bullae as in pemphigus foliaceus and Grover’s disease. The keratoses - punctate keratoses, the ichthyoses, the porokeratoses and Norweigian scabies.
The image below is of a patient with generalised scabies and erythroderma
Purpuric Blisters
Generally indicates sub basal lamina lucida split. You can see them with vasculitis and infection. They can be traumatic or factitial or other blistering disorders in someone with a bleeding problem. Blood in blisters is also commonly seen in EBA , PCT , cicatricial pemphigoid and surprisingly sometimes in bullous pemphigoid. Of these four conditions bullous pemphigoid blisters occur on a red inflamed base. The other three occur on normal coloured skin.
Intertrigo That Will Not Heal
Consider the diagnosis is actually Hailey Hailey or Darier's disease. Consider also Sneddon-Wilkinson disease and secondary infection with candida. Axillary granular parakeratosis is a more modern persistent contact irritant reaction that might present as a non healing intertrigo. It may be a contact allergy to some medication being applied.
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| Axillary granular parakeratosis |
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| Hailey Hailey disease |
Symmetrical Lividity
Seen in young men with cold sweaty cyanotic extremities with some hyperkeratosis. The hyperhidrosis can follow tinea.
The image below is of Hailey Hailey disease
Infiltrates in the Earlobe
If there is a squamous reaction as well consider lupus vulgaris but the differential diagnosis is leprosy, sarcoid, lupus, chilblains and lymphocytoma cutis.
This is an image of leprosy of the earlobe
Other Slides of Interesting Features
Acropustulosis of Hallopeau (sometimes called acrodermatitis). It involves the fingers and the nails are also involved.
Soft corn presents as a white intertriginous area between the fourth and fifth toes.
Scabies may present as keratotic lesions in and on the ears especially in the Norwegian scabies.
Psoriasis, note the salmon pink colour, the three types of scale, the abrupt edges and it is monomorphic. Consider also psoriasis over the sacrum versus lichen simplex chronicus. The latter is usually itchy and may show superficial features of lichenification. Psoriasis in a child can be atypical.
Pityriasis rosea, note the papular variant. Often you get three crops of pityriasis rosea.
When pityriasis rubra pilaris affects the scalp you have an early scaling stage before the more typical thick psoriasiform scale will occur. Fine scale on the scalp is due to atopy, ichthyosis, pityriasis rubra pilaris or a fungus or seborrhoeic dermatitis.
Secondary syphilis on the soles of the foot is a lovely copper colour with a very fine scale.
Acanthosis nigricans presenting as angular cheilitis is often not black but you have the wart like thickening.
Scabies of the nipple present as excoriated dermatitis of the nipple.
Candidiasis of the vulva can be papular but it is still itchy.
Watch xantho erythroderma, which is a variant of large plaque parapsoriasis with yellow splashed on lesions, which can look digitate.
Levido with summer ulceration. There is usually an associated venous stasis with fibrinolytically exhausted vessels leading to thrombosis and ulceration.
Cat scratch disease may present with a sore on the face and big glands in the neck.
Annular lesions on the forehead are due to sarcoid, necrobiosis lipoidica, granuloma annulare and leprosy.
The image below is of Acropustulosis of Hallopeau The atrophy and loss of the nails are the features that distinguishes this condition from pustular dyshidrotic eczema.
The Differential Diagnosis of Papules on the Palms and Soles
Papules include Reiter’s disease, yaws, arsenic, syphilis and porokeratoses. Squamous disorders include psoriasis, pityriasis rubra pilaris, lichen planus and tinea. If you suspect tinea on the palms of the hands look on the back of the hands and look for follicular inflammation.
Other Observations Pityriasis rosea is often atypical in children. Often it is on the face or acral and it can be papular.
The papules of secondary syphilis are seen at the angles of the mouth and the nose.
Paronychia in Reiter’s disease is painless.
In PRP of the face look for the overall erythema and fine scale.
In Darier’s disease there is no real erythema.
In seborrheic dermatitis there is a greasy scale that is easy to remove and in pityriasis rubra pilaris there is erythema with an acuminate scale and keratin.
In the secondary stage of syphilis look for the pigmentation, especially the late secondary stage, as a measure of the inflammatory process.
Remember that oval lesions on the chest can be seen in pityriasis lichenoides as well as pityriasis rosea.
The image below is vasculitis of palms
Red Plaques on the Penis
Consider Erythroplasia of Queyrat, syphilis, Reiter’s, psoriasis, candidiasis and Bowen’s disease.
Compare tinea barbae with bacterial folliculitis. In tinea barbae the hairs fall out and it is often in a country worker whereas in bacterial folliculitis the pustule is around the hair follicle and it is usually painful and the hairs are often intact.
The image below is of psoriasis on the glans.
Vegetating Lesions
On the legs these are often deep mycoses, psoriasis, lichen planus, Darier’s and secondary to lymphedema.
On the flexures consider all the pemphigus types, pemphigoid, Darier’s, Hailey Hailey disease and iododerma. Pemphigus vegetans when it affects the mouth is often worse at the edges. Epidermodysplasia verruciformis can give psoriasis like plaques on the arms but curiously it can also give small white hypopigmented spots like plane warts.
The image below is Darier's disease
Desquamation
Desquamation is really non-recurring exfoliation. Consider the bullous diseases such as staph scalded skin syndrome, toxic epidermal necrolysis and epidermolysis bullosa. Secondly consider dermatitis particularly pompholyx and post dermatitis. Thirdly consider drugs particularly the Retinoids and Vitamin A and fourthly consider toxins as in scarlatina, toxic shock syndrome and staph scalded skin. Palms and soles can take up to 56 days to re epithelialise the epidermis.
The image below is bullous impetigo
Causes of Angular Cheilitis
Consider the mnemonic VISA. The V stands for vitamin deficiency particularly Iron, acrodermatitis enteropathica, agranulocytosis, leukemia and Downs syndrome. The I stands for infection, candida, staph, strep and syphilis. The S stands for other skin diseases including atopic dermatitis, lichen planus, pemphigus and acanthosis nigricans and A for anatomical which simply means a drop in the vertical dimensions of the face due to resorption of the gums with aging. This is probably one of the commonest causes in the elderly of angular cheilitis.
In younger individuals on oral retinoids for acne, this problem is particularly common.
Fissures Around the Ear
Consider granuloma fissuratum due to glasses that are ill fitting. Note that 30% of atopic children have a superolateral fissure behind the ear and also consider seborrheic dermatitis and psoriasis behind the ear causing fissures. Darier’s disease when it is severe can cause fissures here as well but the keratotic papules are usually quite obvious.
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| Probably better named acanthoma fissuratum |
Lupus Vulgaris
90% of cases occur on the face. They are usually symmetrical plaques with brown colour with scarring. The other types that can be seen include plaques, which ulcerate or tumour like or vegetating and there are multiple small papule type, sometimes known as acnitis. The lesions are soft and should show the apple jelly sign. In non-bullous ichthyosiform erythroderma the erythema tends to persist whereas in bullous ichthyosiform erythroderma the erythema goes first. So if you see marked erythema it is non bullous.
Seborrhoeic Dermatitis
Crusting is superficial and greasy with an underlying erythema. If you are considering seborrhoeic dermatitis of the groins check just beyond the erythema for the typical scale. The types of seborrhoeic dermatitis are the petaloid, annular with a finer scale on the inside area, seborrhoeic dermatitis of the scalp gives erythema and starts around a hair follicle, Darier’s disease of the scalp gives no erythema and a pit is left when the scale or papule is removed. Follicular seborrhoeic dermatitis gives an acne like rash on the back. Note that seborrhoeic dermatitis morphologically can be eczematous, psoriasiform, pityriasis like or generalised with erythema. Note that seborrhoeic dermatitis on the body is mainly central and symmetrical. Consider how you would separate Darier’s disease and seborrhoeic dermatitis. Consider the nature of the scale, erythema, the nails, the palms, the mouth and also the white macules you may see in Darier’s.
The image below is mild seb derm
Poikiloderma
Note the types of poikiloderma. Check for a lack of pigment around the follicles on the neck. In dyskeratosis congenita and Fanconi’s syndrome you do get poikiloderma. In dyskeratosis congenita the nails are involved early. You start to get paronychia at 8 to 10 years of age. You may get leukoplakia and form bullae in the mouth and it is an X linked recessive.
Poliosis
Consider the Alezzandrini syndrome giving unilateral vitiligo, retinitis which is unilateral and bilateral deafness.
Compare nevus anemicus and nevus depigmentosis. In nevus depigmentosis the hair is white and in nevus anemicus the stroke test to reduce surrounding erythema will cause the lesions to look the same as surrounding skin.
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| Nevus anaemicus |
Photosensitivity Disorders Such as Pellagra
Note the distribution of this rash particularly in sun exposed areas on the back of the hands, the V of the neck and the face. The eroded split skin dermatitic look of it and if anyone has a light eruption always look in the mouth and see if there is any evidence there. In pellagra the tongue is involved.
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| Pellagra back of hand |
The image below is pellagra of the face.
In non-addisonian generalised pigmentation the mnemonic is DAMN. (Drug Autoimmune Metabolic and Nutritional) The metabolic ones are due to porphyria, hemochromatosis or pellagra.
