* Oral lichen planus (OLP) affects about 50% of patients with skin lichen planus.
* May occur without skin lesions elsewhere.
* All areas inside the mouth can be affected, the commonest sites being the inner side of the cheeks (buccal mucosa), tongue, palate, gums and lips.
* There may be no symptoms but it can cause discomfort, severe pain and ulcers.
* Most cases are seen in middle-aged and much more common in women than in men (75% vs. 25%).
* Oral LP is stable but chronic, with less than 3% of patients having a spontaneous remission in an average 5-year follow-up.
* OLP has more prolonged course than the cutaneous form of the disease.

There are 3 clinical forms of OLP:
1. Reticular LP: symmetrical, asymptomatic, whitish papules in a lace-like pattern (network-like lesions). Occasionally, the papules coalesce forming large, irregular, whitish patches or plaques mimicking leukoplakia. It involves mainly the buccal mucosa (inner aspects of cheeks), and also the tongue or gums and may ulcerate. Plaque OLP is a form of reticular OLP and usually seen in smokers.
2. Erosive/ Ulcerative LP: a common variety usually presents as very painful red erosions often with a whitish border. It most often affects the gums and lips. SCC may complicate longstanding cases of this form of OLP.
3. Atrophic LP: is the rarest type presents as annular atrophic whitish patches.
* Many patients may have mixed types of OLP.
* LP may produce desquamative gingivitis which is particularly difficult to diagnose and often requires biopsy for both histology and DIF to confirm the diagnosis and exclude other autoimmune causes of desquamative gingivitis.
* Lichen planus may rarely (1%) lead to oral SCC which occurs only in patients with erosive/ ulcerative LP (doesn’t occur in the reticulate pattern). * Of the oral LP patients who develop oral SCC, about 45% have only one cancer. The majority develop multiple cancers, and close vigilance is recommended in these patients. So persistent oral ulcers should undergo biopsy.

Differential Diagnosis: The most important differentials are:
1. Oral Lichenoid Lesions (OLL) caused by medications (e.g. Gold), Dental Amulgum and Graft versus host disease.
2. Desquamative gingivitis caused by immunoblistering diseases.
3. Leukoplakia
4. SCC (Ulcerative LP)

Management of oral lichen planus: All available therapeutic modalities and options are unable to change the course of OLP. They may be useful in symptomatic relief or temporary clearance of the lesions.
I. Topical therapies:
(A) Topical numbing (LA) agents can be used to provide temporary relief for painful areas.

(B) Corticosteroids may reduce inflammation related to OLP. They may be given as a mouthwash, paste, ointment, gel or sprays applied directly to the mucous membrane (topical). Triamcinolone in an emollient dental paste or fluticasone nasal preparations are often prescribed. Intralesional triamcinolone injections may be used for focal unresponsive lesions.

(C) Retinoids: can be applied as a topical ointment, but they’re not commonly used to treat oral lichen planus. Topical treatment may irritate the mucous membranes of the mouth. Because topical retinoids also can cause birth defects, the drug shouldn’t be used by women who are pregnant or planning to become pregnant in the near future.

(D) Calcineurin Inhibitors: these can suppress or modify the immune response. They may be used as ointments, gels, or mouth rinse. Treatments that suppress immune system abnormalities may improve more severe lesions and lessen pain. Several reports have shown the effectiveness of topical calcineurin inhibitors in OLP. Examples of these topical medications include tacrolimus (Protopic) and pimecrolimus (Elidel). Topical tacrolimus 0.1% ointment has become standard treatment in erosive OLP. Burning may occur initially but can be reduced by concomitant use of topical steroids or initial use of a lower strength of tacrolimus ointment. Higher concentrations, up to 0.3%, also may be used. Most patients have a partial but significant response, with increased ability to eat with much less pain. Pimecrolimus can be used successfully in patients intolerant of topical tacrolimus. Sustained remissions are rare, and chronic use is usually required to maintain remission. Ciclosporine, another calcineurin inhibitor can be used as mouth rinse in OLP, however, it is ineffective.

II. Systemic therapies: are seldom used for OLP unless other parts of the body also are affected. However, when indicated (severe cases unresponsive to topical therapies or cases associated with involvement of other parts of the body), they may include:

(A) Systemic corticosteroids: 20-60 mg prednisone per day may control OLP but the main problem is the inevitable side effects.

(B) Systemic retinoids (acitretin or isotretinoin).

(C) Immunosupressives and Cytotoxics: Ciclosporine, Azathioprine, Cyclophsphamide, Mycophenolate mofetil and Methotrexate. All can induce remission in severe cases of cutaneous and oral LP.

(D) Heparin: Low-molecular-weight heparin (Enoxaparin), 3 mg injected subcutaneously once a week may result in remission of cutaneous and reticulate oral LP.

(E) Hydroxychloroquine in standard doses can be effective for cutaneous, oral, and genital LP.

(F) Thalidomide: 50–150 mg daily, can improve refractory oral and cutaneous LP.

(F) Others: Griseofulvin, Dapsone, Metronidazole.

(G) PUVA, photodynamic therapy, and 308-nm excimer laser have been effective in oral LP.

Mammary Paget disease
* Synonym: Paget disease of the breast and Paget disease of the nipple.

* An uncommon skin cancer characterized by a chronic eczema-like rash of the nipple and adjacent areolar skin. It is caused by the invasion of the epidermis by cells from an underlying intraductal carcinoma of the breast (Paget cells).

* Age: Most commonly between 50 and 60 years of age.
* Sex: women > men (very rare in men)
* Usually Mammary Paget disease is associated with an underlying breast adenocarcinoma.
* Between 1% and 4% of breast carcinomas present with PD.
* About 5% of patients have PD without confirmed evidence of underlying carcinoma, and the remaining 95% have either an invasive or an intraductal carcinoma.
* Sometimes it is difficult to detect underlying breast Ca on clinical examination or by mammogram.
* In rare cases, even when no underlying carcinoma is found on surgical removal, the sentinel node may be positive.

* Extramammary Paget disease is a similar condition that involves the skin of female and male genitalia.
Clinical Presentation:
* Most patients present with an itchy, burning erythematous rash on and around the nipple area. There may be swelling, oozing nipple discharge, bloody nipple discharge, scaling, ulceration and an inversion (retraction) of the nipple. The condition usually is sharply marginated and in most cases unilateral and recalcitrant to treatment (only one nipple is affected although rare cases of involvement of both nipples have been seen).
* In advanced cases, a subjacent mass and ipsilateral axillary adenopathy may be palpable.
* At times, PD may be hyperpigmented and may mimic melanoma.

Differential Diagnosis:
Clinically:
1. Eczema: Atopic eczema, contact eczema and LSC.
2. Papillary adenoma of the nipple.
3. Hyperkeratosis of the nipple and areola (Unilateral).
Histopathologically:
1. Pagetoid melanoma.
2. Bowen’s disease.

Diagnosis:
It is confirmed by skin biopsy of the lesion which reveals the presence of Paget cells: large, round, pale-staining cells with large nuclei. Intercellular bridges are absent. The cells appear singly or in small nests between the squamous cells. Atypical cells may be “spat out” into the stratum corneum. Frequently, a layer of basal cells separates the Paget cells from the basement membrane and is seen crushed beneath the nests of Paget cells. This histologic feature helps to distinguish PD from pagetoid melanoma and Bowen’s disease. In the dermis, an inflammatory reaction is often present.
Paget cells have characteristic staining profile being positive to many cell markers.
Skin biopsy may also determine whether there is underlying cancer, although some breast carcinomas are not seen because they are situated more deeply in the breast tissue.
A mammogram may accurately locate the underlying Ca prior to breast biopsy.

Treatment:
Mastectomy (removal of the breast) is often necessary. Alternatively, it can be widely locally excised along with samples of tissue taken from nearby lymph nodes in the armpit. Sometimes conservative treatment such as partial nipple excision, wedge excision, cone excision, radiotherapy, or a combination of these may be used in women with less advanced stages of the disease. However, recurrence is common in these cases.
* Prognosis: Depends on extent of tumor invasion.
Patients presenting with a palpable breast mass typically have more advanced disease and lower 5-year survival.

Pruritic Urticarial Papules and Plaques of Pregnancy (PUPPP).
Synonym: Polymorphic eruption of pregnancy
Rash:
* Erythematous papules and plaques that begin within the abdominal striae then spread over a few days to involve the abdomen, buttocks, thighs. The arms and legs are involved in some cases. Lesions on or above the breasts are rare i.e. the upper chest, face, and mucous membranes are generally spared.
* There is often a pale halo around the papules. These papules coalesce to form large red, urticarial plaques.
* Intense pruritus is characteristic.
* Most cases occur in primigravidas (75%).
* More common in those carrying twins or triplets.
* Begins late in the third trimester and resolves (remits) at or few weeks after delivery. Rarely, it may persist for longer (this may relate to retained placental products).
* Postpartum onset or exacerbation is uncommon.
* The well-being of the mother and fetus is not affected by PUPPP.
* Rarely the newborns manifest the rash of PUPPP but this soon fades.
* Rarely recurs with subsequent pregnancies. If it occurs, it is likely to be milder.
Histopathology:
* Mainly shows upper and mid-dermal perivascular lymphohistiocytic infiltrate with a variable number of eosinophils and dermal edema.
* DIF test shows negative or nonspecific results.
Differential diagnosis:
* The most important one is Pemphigoid gestationis.
* Other pregnancy related dermatoses.
Treatment:
* There is no curative treatment apart from delivery!. Symptoms can be controlled using:
1. Liberal amounts of emollients.
2. Topical steroids (potent) applied thinly twice daily are usually required.
3. Antihistamines – conventional antihistamine tablets appear safe in late pregnancy (though they may make the baby drowsy on delivery).
4. A few patients require prednisone.

Trichotillomania (Hair-pulling habit)
* A minor comfort habit in children like nail-biting and lip-licking.
* A type of traumatic localized non-scarring alopecia not uncommonly seen in children.
* Occurs more in girls than in boys.
* Affected individuals seldom have major psychiatric disorders, however some may have obsessive compulsive neurosis and when they are under the influence of psychological tension they develop and accustom the habit of twisting and pulling their hair resulting in localized non-scarring alopecia.
* Commonly involved sites are the sides of the scalp and the fronto-vertical area.
* A very important diagnosis-aiding feature is that hairs in the affected area are usually broken at different lengths from the scalp surface.
* The diagnosis can usually be made on the history, but some parents do not know what is going on.
The main differential diagnoses are:
1. Alopecia areata
2. Traction alopecia
3. Tinea capitis

* The bald areas in trichotillomania do not show the exclamation-mark hairs of alopecia areata, or the scaling and inflammation of scalp ringworm. The patches are irregular in outline and hair loss is never complete.

Management:
1. Reassurance
2. Explanation to the parents or the patient that it is due to the habit of hair pulling.
3. Tranquilizers may be given.
4. Referral to psychiatrist may be necessary in some cases.

Prognosis: trichotillomania is usually of little consequence as the habit often goes away most quickly if it is ignored. However, more severe degrees of hair-pulling are occasionally seen in disturbed adolescents and in those with learning difficulties; then the outlook for full regrowth is less good, even with formal psychiatric help.

PELLAGRA
Pellagra usually results from a deficiency of nicotinic acid (niacin, vitamin B3) or its precursor amino acid, tryptophan.
Causes:
1. Dietary deficiency: inadequate dietary niacin and/or tryptophan is seen mainly in developing countries or poverty stricken areas. Pellagra is associated classically with a diet almost entirely composed of corn, sorghum, or millet.
2. Chronic alcoholism: the most common cause in the developed countries.
3. Hartnup disease (impaired absorption of tryptophan).
4. Carcinoid tumors, which divert tryptophan to serotonin.
5. GI disorders: Crohn’s disease, ulcerative colitis and GI surgery.
6. Prolonged intravenous supplementation.
7. Psychiatric disorders including anorexia nervosa.
8. Medications: most often isoniazid, azathioprine (and its metabolite 6-mercaptopurine), 5-fluorouracil, ethionamide, and pyrazinamide. Rarely, the anticonvulsants (hydantoins, phenobarbital, and carbamazepine) may produce pellagra.

Clinical features
* Pellagra is a chronic disease affecting the GI tract, nervous system, and skin; thus the mnemonic of the “3 Ds”— diarrhea, dementia, and dermatitis. If left untreated, death is the usual outcome.
* At the onset, the patient has weakness, loss of appetite, abdominal pain, diarrhea (occurs in 50% of cases), mental depression, and photosensitivity.
* Skin lesions may be the earliest sign, with phototoxicity the presenting symptom in some cases.
* Neurologic and GI symptoms can occur without skin changes.
* In the later stages, the neurologic symptoms may predominate. Apathy, depression, muscle weakness, paresthesias, headaches, and attacks of dizziness or falling are typical findings. Hallucinations, psychosis, seizures, dementia, neurologic degeneration, and coma may develop.

* Phototoxic sun burn-like rash occurs on the face, neck, and upper chest (Casal’s necklace), extensor arms and backs of the hands. The rash is usually symmetrical with a clear edge between affected and unaffected skin. There may be itching or a burning sensation.
In severe cases, the eruption may be vesicular or bullous (wet pellagra). After several phototoxic events, thickening, scaling, and hyperpigmentation of the affected skin occur to have a copper or mahogany hue.

* The bridge of the nose is characteristically dull red with fine, yellow, powdery scales over the follicular orifices (sulfur flakes).

Management:
* If the characteristic skin findings are present, the diagnosis of pellagra is not difficult clinically.
* Pellagra can be effectively cured with intravenous or oral niacin or nicotinamide. Nicotinamide, 100 mg three times daily for several weeks, should be given. Within 24-48 h of niacin therapy initiation, the skin lesions begin to resolve, confirming the diagnosis.
* Dietary treatment to correct the malnutrition is essential. A high protein diet supplemented with B-group vitamins is needed for complete recovery.
* Fluid and electrolyte loss from diarrhea should be replaced, and in patients with GI symptoms possibly interfering with absorption, initial IV supplementation should be considered.
* Alcoholism and other factors that may have led to pellagra (secondary pellagra) must be corrected.

Dermogrphism
Synonyms: dermatographism, dermatographia and dermatographic urticaria.
Dermographism is an exaggerated whealing tendency when the skin is stroked and usually presents as a sharply localized edema or wheal, with a surrounding erythematous flare occurring in seconds to minutes after the skin has been stroked.
Dermographism is the most common form of physical urticaria, followed by cholinergic urticaria. It may occur with other types of urticaria including those due to cold or pressure.

Plane wart

* Flat warts may result in a considerable cosmetic concern and fear of spread and contagiousness.
* May represent a therapeutic challenge and occasionally dilemma especially in children with face involvement.
* Shaving and hair epilation should be abandoned if relevant areas are involved.
* Golden rule: with any treatment modality, at least 3 months of management is considered a reasonable therapeutic trial. So no treatment should be stopped too quickly.
* Put in mind that flat warts frequently undergo spontaneous remission, so
avoid potentially scarring therapies.
* For few lesions you may consider:
1. Light cryotherapy.
2. Topical salicylic acid products (up to 20% concentration).
3. Tretinoin cream once or twice daily, in the highest concentration tolerated to produce mild erythema of the warts.
4. Tazarotene cream or gel.
5. Imiquimod 5% cream used up to once daily can be effective. If the warts fail to react initially to the imiquimod, tretinoin may be used in conjunction.
6. 5-FU cream 5%, applied twice daily, may be effective (in resistant cases).
* For refractory lesions:
1. laser therapy in very low fluences or photodynamic therapy (PDT) might be considered before electrodesiccation because of the reduced risk of scarring.
2. Immunomodulatory therapy: Ranitidine, 300 mg twice daily or Cimetidine (25–40 mg/kg).
3. Immunotherapy: using:
* Dinitrochlorobenzene (DNCB)
* Squaric acid
* Diphencyprone
* Intralesional Candida or other antigens
These can be used on limited areas of flat warts, with the hope that the immune response will clear distant warts.
4. Oral isotretinoin therapy at 30 mg/day/ 3 months might be considered when the previous topical approaches have failed.

Dermatitis artefacta (DA) is a condition in which skin lesions are solely produced or inflicted by the patient’s own actions due to underlying psychological problem.
Synonym: (Factitial dermatitis)

What is the difference between DA and malingering?
DA is self-inflicted skin lesions with the intent to elicit sympathy, whereas malingering is self-produced lesions either to escape responsibility, or collect disability insurance (attempt to secure an insurance claim) i.e. the objective behind malingering is material gain while in DA there is an unconscious goal of gaining attention and assuming the sick patient role.

* DA is more common among females than males with a ratio of 3:1.
* It commonly occurs in teen’s age group or early adulthood.
* DA often is encountered among:
(a) Persons who are emotionally immature.
(b) Those having psychosocial or interpersonal difficulty.
(c) Persons with an attention seeking behavior.

How to expect a rash to be DA?
1. Lesions do not conform to those of known dermatoses. However, occasionally it may closely simulates a known dermatosis that it becomes very difficult to differentiate !
2. Lesions having bizarre shapes with irregular outlines in a linear or geometric pattern.
3. Lesions are usually clearly demarcated from surrounding normal skin.
4. The lesions usually present all of a sudden and do not evolve gradually without any prior signs or symptoms.
5. The lesions usually found on sites that are readily accessible to the patient’s hands e.g. face, hands, arms or legs. The lesions are rarely seen on the right hand, right wrist, or right arm, unless the patient is left-handed.
6. The patients will usually deny that the rash is self induced.
7. Often there is a “hollow” history and the patient isusually unable to detail how the lesions appeared or evolved.

Mechanism of induction: Lesions may be produced by a variety of mechanical or chemical means, including fingernails, sharp or blunt objects, lit cigarettes and application or injection of chemical irritants and caustics.

Clinically: The appearance of lesions varies depending on methods used to injure the skin. The lesions range from red patches, swelling, blisters, denuded areas, crusts, cuts, burns, gangrene and scars. At times the only sign may be the indefinitely delayed healing of an operative wound, which is purposely kept open by the patient.

Management
1. Avoid direct confrontation with the patient. Instead the doctor should create an empathetic and non-judgemental environment.
2. It is best not to reveal any suspicion of the cause to the patient and to establish the diagnosis definitively without the patient’s knowledge.
3. Consultation with an experienced psychiatrist is prudent, although this is often refused.
Prognosis: Resolution of the current underlying psychological problem will bring about a cure for the time being but dermatitis artefacta tends to wax and wane with the circumstances of the patient’s life.