Tutorial 3

 

These tutorials are particularly directed at third and fourth year registrars. They are meant to give you a broad introduction to clinical dermatology particularly aspects of differential diagnosis. They will use online atlases ,PubMed and eMedicine websites as resource materials as well as the cases in the Dermconsult website itself. The format is based on one used by Ken Paver some years ago.

Search eMedicine          Search Perplexity AI

Topics covered in this tutorial

1. The DD of papules.
2. Eyelid papules.
3. Acral papules.
4. Oral papules
5. Yellow papules
Questions will also be asked on the following disorders-

Lymphomatoid papulosis.
Sarcoidosis.
Pseudoxanthoma elasticum
Lipoid proteinosis
Lichen amyloid


The Diagnosis of Papular Diseases

These are probably best diagnosed by dividing them into papules on certain sites, papules with certain colours and papules with certain patterns. 

 The sites are namely the eyelids, the mouth, acral and follicular. The colours are yellow, blue black and skin coloured and the patterns are linear, circinate, single, multiple, symmetrical, those associated with bullae, scaling and non scaling.

Oral Papules The differential diagnosis includes oral florid papillomatosis, Darier's Disease, tuberous sclerosis, Cowden's Syndrome, acanthosis nigricans, multicentric reticulo histiocytosis, lipoid proteinosis, Goltz Syndrome, Heck's Disease.

Eyelid Papules Naevi, warts particularly mollusca, syringomas, sarcoidosis,  acnitis, amyloidosis, See this case of lipoid proteinosis.

Acral Papules Warts, acrokeratosis verruciformis, epidermodysplasia verruciformis, Gottron's papules, multicentric reticulo histiocytosis, sarcoidosis, lichen planus, granuloma annulare.

Asymptomatic labial papules in a teenager

The photo below is of lymphomatoid papulosis

Syndromes with Acanthosis Nigricans

These include Prader Wili, Sjogren Larsen, Rudd's, Down's, Lawrence Seip,  Leprechaunism, Wilson's Disease, Polyendocrine Syndrome. In the benign form of acanthosis nigricans most patients show features of obesity and insulin resistance. The malignant form of AN is far less common, and, in one study, only 2 of 12,000 patients with cancer had signs of AN.

GlobalSkinAtlas Acanthosis nigricans  eMedicine-Acanthosis nigricans eMedicine-Lawrence-Seip Syndrome

Symmetrical black plaques on the toes

Syndromes with Poikiloderma

The list includes Rothmund Thompson Syndrome, Bloom's Syndrome, Cockaynes, Dyskeratosis Congenita, Erythropoietic Proto Porphyria and Werner's Syndrome.

The age of onset of the poikiloderma is a good way of separating out these conditions.

Syndrome	Typical onset of poikiloderma	Key associated features in children	Malignancy risk
Rothmund–Thomson syndrome (poikiloderma congenitale, RECQL4)	Facial rash in infancy, evolving to poikiloderma by 3–5 yearsncbi.nlm.nih+1	Short stature, sparse hair/eyebrows, photosensitivity, juvenile cataracts, skeletal anomalies (radial/thumb defects, bone dysplasia), dental anomalies, GI symptoms, hypogonadism, possible developmental delaylink.springer+2	High risk of osteosarcoma in late childhood/adolescence and non‑melanoma skin cancers; other internal malignancies reportedonlinelibrary.wiley+1
Kindler syndrome (KIND1/FERMT1)	Poikiloderma appears in early childhood after infancy blisteringpmc.ncbi.nlm.nih+2	Acral trauma‑ and photosensitive blistering in infancy, photosensitivity, progressive poikiloderma on photoexposed sites, skin atrophy, mucosal fragility, strictures (oral, esophageal, urogenital), periodontitispmc.ncbi.nlm.nih+1	Increased risk of cutaneous squamous cell carcinoma in adulthood reportedjamanetwork
Poikiloderma with neutropenia (C16orf57/USB1)	Early childhood poikiloderma, often first years of lifeonlinelibrary.wiley+1	Chronic neutropenia with recurrent sinopulmonary and skin infections, nail dystrophy, palmoplantar hyperkeratosis, short stature, facial dysmorphism; bone marrow failure may evolvemedlineplus	Elevated risk of myelodysplastic syndrome and acute myeloid leukemiaonlinelibrary.wiley+1
Dyskeratosis congenita (telomere biology disorders)	Childhood or adolescent poikiloderma, often reticulated pigmentation on neck/upper chestonlinelibrary.wiley+1	Classic triad: abnormal reticulated pigmentation, nail dystrophy, oral leukoplakia; plus bone marrow failure, pulmonary and hepatic fibrosis, developmental delay in some subtypessciencedirect	High risk of bone marrow failure, myeloid malignancy, solid cancersonlinelibrary.wiley+1
Hereditary sclerosing poikiloderma (Weary type and related)	Early childhood onsetsciencedirect+1	Generalized or acral poikiloderma with progressive dermal fibrosis/sclerosis, flexion contractures, possible tendon/ligament involvement; usually little systemic malignancy risk reportedsciencedirect	Malignancy risk less well defined; not a classic cancer‑predisposition syndromeonlinelibrary.wiley+1
Hereditary fibrosing poikiloderma (e.g. POIKTMP/FAM111B)	Infancy/early childhood poikilodermaonlinelibrary.wiley+1	Progressive poikiloderma, tendon contractures, myopathy, lipodystrophy; systemic fibrosis may involve lungs, pancreas, and other organsonlinelibrary.wiley	Data limited; some reports of internal organ dysfunction rather than frank cancer predispositiononlinelibrary.wiley

Chronic plaques in a patient with ataxia telangiectasia

The photo below illustrates acanthosis nigricans on the neck  Click here to view this case

Cowden's Syndrome

In this condition there are often pearly papules on the palms and soles with also papules at the side of the lips and tricholemmonas on the face. This syndrome is associated with internal malignancies, particularly of the breast and thyroid. Note-If you see a patient with what you think are warts on the face have a close look at their gums and see if there are verrucous lesions there. Then look more carefully at the skin for lipomas, fibromas lymphangiomas and angiomas. The warty lesions on the skin will be trichilemmomas.

Other Central Facial Papules

Multiple trichilemmomas        Image
Multiple trichilemmomas
Adenoma sebaceum (multiple angiofibromas)
Darier disease
Syringomas (usually located under eyes as opposed to perinasally)
Fibrofolliculomas (in Birt-Hogg-Dube syndrome)    Image
eMedicine-Cowden's Syndrome
Multiple facial papules in an adult

Trichoepithelioma

Trichoepithelioma is a skin coloured papule found on the nasal labial folds and eyelids. It is worse at puberty. This should be compared with tuberous sclerosis which is better at puberty. Trichoepitheliomas are often found in association with cylindromas. It is due to the presence of an autosomal dominant gene on chromosome 9 which can show dimorphism and variable penetration. Linear and dermatomal forms of trichoepithelioma may sometimes be seen as well as a variant with a large hemifacial plaque.

eMedicine-Trichoepithelioma         Image

The photo below is a solitary desmoplastic trichoepithelioma

Lichen Amyloid

Lichen Amyloid is a papular disorder seen particularly on the lower limbs with the pathology being in the lower dermis. This can be compared with lichen myxedematosus where the lesions are usually seen in the upper limb and the pathology is in the upper dermis. The lesions of lichen amyloid are brown, slightly scaly, discrete papules but often they will join up to form infiltrated plaques, particularly over the shins. They are usually very itchy. The papules of lichen myxedematosus are often waxy, dome shaped or flat topped papules. They also can coalesce into plaques and linear forms are known.

GSA Lichen Amyloidosis      eMedicine-Lichen Amyloid

Skin induration with multiple flesh coloured papules

Kyrle's Disease

These are hyperkeratotic papules up to 1 cm in diameter with confluence sometimes producing polycyclic plaques. It spares the palms and soles. It is found especially on the legs in the 30 to 60 year age group.

eMedicine-Kyrle's Disease        Image

Question: Are mucosal lesions present in lichen myxedematosus?

Answer: Mucosal lesions are absent in lichen myxedematosus

The photo below is lichen amyloidosis

Itchy hyperkeratotic papules particularly on the lower legs

Lipoid Proteinosis

Note that this condition is often seen at birth and is associated with hoarseness in the newborn baby. This is due to an infiltrate in the vocal chords. The lesions typically affect the oral mucosae. The tongue is often like wood. Eyelid papules are commonly seen in this condition.

Globalskinatlas- Lipoid Proteinosis          eMedicine-Lipoid Proteinosis

Buschke-Ollendorff Syndrome

Buschke-Ollendorff Syndrome is an autosomal dominant disorder with widespread dermal papules and plaques, mainly asymmetrically on the trunk and limbs. Osteopoikilosis is seen in the long bones. Connective tissue naevi are also seen in tuberous sclerosis and because at least 50% of cases of this condition are new mutation, every patient with a connective tissue naevus should be checked for evidence of tuberous sclerosis.

eMedicine-Buschke-Ollendorf Syndrome         Image

Widespread pea sized papules and gooseflesh plaques in a 44 years old woman

Question 1: What skull x-ray features are pathognomonic for lipoid proteinosis?

Question 2: Early stage lipoid proteinosis may produce bullae and pustules which heal with acne like scars. What other condition may this simulate?

Question 3: What two features are common to both tuberous sclerosis and lipoid proteinosis?

Answer 1: Sickle-shaped calcifications found dorsal and lateral to the sella turcica in skull x-rays are pathognomonic.

Answer 2: Erythropoietic Protoporphyria.

Answer 3: Both have cerebral calcification and papules on the eyelids.

Angiofibromas of tuberous sclerosus

Periungual fibroma

Cutaneous fibroma plaque

Sarcoidosis

The skin involvement of sarcoid is either specific showing granulomas on histology or non-specific, mainly reactive such as erythema nodosum. Skin lesions appear before systemic disease in 20% of cases, there is a simultaneous appearance in 50% and in 30% the skin lesions may occur up to 10 years after the systemic disease, often when oral steroids are withdrawn in pulmonary sarcoidosis. Papular sarcoid is particularly common on the face.

Global Skin atlas - Sarcoidosis              eMedicine-Sarcoidosis

Off-Centre Fold Recurrent Pruritic papules in a 74 years old man An Unusual cause of hair loss Erythroderma in a patient with arthritis,uveitis and dyspnoea Hypopigmentation of the extremities

The photo below is annular sarcoidosis 

Small sarcoidal papules looking like granulomatous rosacea

Question 1: What are the various patterns of sarcoidosis and where may they be found?

Question 2: What systemic features may be seen with lupus pernio?

Question 3: Do you get sarcoidosis in the mouth?

Answer 1: Annular - the face and forehead.
Papular - the face
Nodular - the trunk
Angiolupoid - the eyelids
Chilblain-like - the ears, the nose, the cheeks
Scar like - needless to say in scars
Ulcerative - on the legs
Hypopigmented - on the trunk
Erythrodermic - all over the body
Ichthyosiform - particularly the trunk
Alopecia - obviously the scalp
Answer 2: 75% of cases have respiratory tract involvement, 40% have granulomas in bones with punched out cysts, generally on the fingers. Eye lesions occur in about 40% of cases.

Answer 3: Yes, there may be pinhead sized papules, particularly on the hard palate, tongue and buccal mucosa but they may coalesce to form a plaque.

Yellow Papules

Yellow Papules

A mnemonic for yellow papules is SEXI Grannies. S stands for sebaceous, E for elastotic disorders, X for xanthomas, I for infiltrates, particularly lipoid proteinosis, lichen amyloid, EPP and colloid milium. Grannies stands for granulomas.

GSA - Pseudoxanthoma elasticum                eMedicine-Pseudoxanthoma elasticum

Multiple light yellow papules

Pseudoxanthoma Elasticum

The photo below is of colloid milium.The pale area has been lasered with a CO2 laser.

Question: What are angioid streaks?

Answer: They are breaks in the elastic membrane of Bruch at the back of the eye. Eight five percent of PXE patients will show these. These lesions appear earlier than the skin changes and may be the only sign of the disease for years. Angoid streaks are not diagnostic for PXE and may be seen in several other skin diseases and Paget's Disease of bone and Sickle Cell Disease. The papules in PXE are yellowish to cream coloured, the skin is crepe like, lax with redundant folds, the so-called plucked chicken skin. It is often seen on the neck or the inside of the upper arms.

Cowden's Syndrome

Trichilemmomas are a specific cutaneous marker for Cowden's Syndrome. These lesions particularly occur on the head and neck. Patients with Cowden's Syndrome have a marked increase in carcinoma of the breast, thyroid and colon. Other benign features include acral keratotic papules and oral mucosal papules.

Multiple facial papules in an adult

The photo below is of perifollicular fibromas

Question: How would you differentiate histologically between a fibro folliculoma and a perifollicular fibroma?

Answer: In fibro folliculoma there is proliferation of the follicular epithelium as strands extending into a well circumscribed mantle of connective tissue. In perifollicular fibroma the hair follicle is generally unaltered but the follicles are surrounded by a concentric arrangement of collagen fibres. Both lesions are seen in the autosomal dominant disorder known as the Birt-Hogg-Dube Syndrome. Individuals with this syndrome and their relatives should have abdominal tomography for renal cancers, ultrasound screening for renal tumours

Lymphomatoid Papulosis

These lesions usually occur in crops anywhere on the body. There may be very few lesions. The lesions are similar to those of pityriasis lichenoides et varioliformis acuta except that they have a greater tendency to necrosis. Some of the lesions have a tendency to heal spontaneously. The lesions often heal with scarring.

GSA - Lymphomatoid Papulosis        eMedicine-Lymphomatoid Papulosis

Red nodules on the arm of a patient with breast cancer

The photo below is lymphomatoid papulosis .This subsequently evolved into a CD 30 positive T cell lymphoma 

Question: What is the most common associated lymphoma with lymphomatoid papulosis?

Answer: Mycosis fungoides in 40% a CD 30-positive T cell lymphoma in 30% and Hodgkin's Disease in 25%. Note that the presence of clonal rearrangement in lymphomatoid papulosis lesions is not predictive of the behaviour of that lesion or the case in general.

What are the skin signs of Dermatomyositis?

Periocular violaceous erythema with ragged cuticles and periungual capillary dilatation. There are often violaceous papules on the legs like lichen planus and erythema, particularly on the dorsal surfaces of the knees and elbows. Photo sensitivity is often seen. Calcification occurs particularly in children.

A patient with dermatomyositis and linear streaks on the back Dermatomyositis-Practical aspects

Finger Pulp Ulcers and Scars

These can be due to Raynaud's Disease, perniosis, scleroderma, systemic lupus, cryoglobulinemia, rheumatoid arthritis and sub acute bacterial endocarditis.

Cause category	Key mechanisms / examples	Notes / typical context
Poor blood flow (digital ischemia)	Raynaud’s phenomenon, prolonged vessel narrowing, ischemia of fingertip skin	Fingers may change colour with cold or stress; can progress to “digital” ulcers.
Systemic sclerosis / scleroderma	Scarring and narrowing of small arteries, recurrent tip ulcers	Often very painful ulcers at tips or under nails; common in scleroderma.
Trauma and pressure	Repetitive minor trauma (tapping, tools, instruments, sports, biting/picking)	Dry or thin skin splits; in poor circulation, small injuries become chronic ulcers.
Infection	Paronychia, felon, infected hangnails, other local finger infections	Can ulcerate if untreated; recurrent infections may leave pitted or thickened scars.
Connective tissue / vasculitic disease	Lupus, rheumatoid arthritis, vasculitis affecting small vessels	Vessel inflammation and occlusion → fingertip ulcers, sometimes in multiple digits.
Metabolic / vascular risk factors	Diabetes, smoking, high blood pressure, high cholesterol	Microvascular disease and poor healing increase ulcer risk and delay recovery.
Occupational / chemical exposure	Irritants (detergents, solvents), wet work, vibration tools	Skin cracking and splitting, Raynaud-like changes in some workers using vibrating tools.
Neurological / behavioural factors	Neuropathy (numbness), habitual picking or self-injury	Injuries go unnoticed or are self-inflicted, become chronic wounds and scars.

Ragged cuticles of dermatomyositis

Tutorial 31

 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.

Axillary granular parakeratosis

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.

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.

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.

Pellagra back of hand

The image below is pellagra of the face. 

Some other points

 In non-addisonian generalised pigmentation the mnemonic is DAMN. (Drug Autoimmune Metabolic and Nutritional) The metabolic ones are due to porphyria, hemochromatosis or pellagra. 

Note also in the lesions of secondary syphilis the scale is all over the lesion compared with the peripheral scale of pityriasis rosea and the scale of candidiasis is right on the outside.

 If at any time you seem to have a unilateral seborrhoeic dermatitis on the face be aware of Bowen’s disease and a superficial BCC in the nasal labial fold leading you astray.