Lichen planus has a unique microscopic appearance that is similar between cutaneous, mucosal and oral. A Periodic acid-Schiff stain of the biopsy may be used to visualise the specimen. Histological features seen include:

- thickening of the stratum corneum both with nuclei present (parakeratosis) and without (orthokeratosis). Parakeratosis is more common in oral variants of lichen planus.

- thickening of the stratum granulosum

- thickening of the stratum spinosum (acanthosis) with formation of colloid bodies (also known as Civatte bodies, Sabouraud bodies) that may stretch down to the lamina propria.

- liquefactive degeneration of the stratum basale, with separation from the underlying lamina propria, as a result of desmosome loss, creating small spaces (Max Joseph spaces).

- Infiltration of T cells in a band-like pattern into the dermis "hugging" the basal layer.

- Development of a "saw-tooth" appearance of the rete pegs, which is much more common in non-oral forms of lichen planus.

The differential diagnosis for OLP includes:

- Other oral vesiculo-ulcerative conditions such as Pemphigus vulgaris and Benign mucous membrane pemphigoid

- Lupus erythematosus, with lesions more commonly occur on the palate and appear as centrally ulcerated or erythematous with radiating white striae. In contrast, OLP and lichenoid reactions rarely occur on the palate, and the striae are randomly arranged rather than radial.

- Chronic ulcerative stomatitis

- Frictional keratosis and Morsicatio buccarum (chronic cheek biting)

- Oral leukoplakia

- Oral candidiasis

The disease often goes undiagnosed for several years, as it is sometimes not recognized and misdiagnosed as thrush or other problems and not correctly diagnosed until the patient is referred to a specialist when the problem does not clear up.

A biopsy of the affected skin can be done to confirm diagnosis. When a biopsy is done, hyperkeratosis, atrophic epidermis, sclerosis of dermis and lymphocyte activity in dermis are histological findings associated with LS. The biopsies are also checked for signs of dysplasia.

It has been noted that clinical diagnosis of LS can be "almost unmistakable" and therefore a biopsy may not be necessary.

Pemphigus is a group of autoimmune blistering diseases that may be classified into the following types:

The disease can last for a considerably long time. Occasionally, "spontaneous cure" may ensue, particularly in young girls.

Lichen sclerosus is associated with a higher risk of cancer. Skin that has been scarred as a result of lichen sclerosus is more likely to develop skin cancer. Women with lichen sclerosus may develop vulvar carcinoma. Lichen sclerosus is associated with 3–7% of all cases of vulvar squamous cell carcinoma. In women, it has been reported that 33.6 times higher vulvar cancer risk is associated with LS. A study in men reported that "The reported incidence of penile carcinoma in patients with BXO is 2.6–5.8%".

Pemphigus defines a group of autoimmune interepithelial blistering diseases that are characterized by loss of normal cell-cell adhesion (acantholysis), and by the presence of pathogenic (predominantly IgG) autoantibodies reacting against epithelial adhesion molecules. Pemphigus is further divided in two major subtypes: pemphigus vulgaris (PV) and pemphigus foliaceus (PF). However, several other disorders such as IgA pemphigus, IgE pemphigus, pemphigus herpetiformis, drug induced pemphigus, Senear Usher syndrome and endemic pemphigus foliaceus exist;recognized by a dermatologist from the appearance and distribution of the skin lesions. It is also commonly diagnosed by specialists practicing otolaryngology- head and neck surgery, periodontists, oral and maxillofacial surgeons and eye doctors, as lesions can affect the eyes and mucous membrane of the oral cavity. Intraorally it resembles the more common diseases lichen planus and mucous membrane pemphigoid. Definitive diagnosis requires examination of a skin or mucous membrane biopsy by a dermatopathologist or oral pathologist. The skin biopsy is taken from the edge of a blister, prepared for histopathology and examined with a microscope. The pathologist looks for an intraepidermal vesicle caused by the breaking apart of epidermal cells (acantholysis). Thus, the superficial (upper) portion of the epidermis sloughs off, leaving the bottom layer of cells on the "floor" of the blister. This bottom layer of cells is said to have a "tombstone appearance".

Definitive diagnosis also requires the demonstration of anti-desmoglein autoantibodies by direct immunofluorescence on the skin biopsy. These antibodies appear as IgG deposits along the desmosomes between epidermal cells, a pattern reminiscent of chicken wire. Anti-desmoglein antibodies can also be detected in a blood sample using the ELISA technique.

The diagnosis is normally made based upon the clinical appearance and history. Tissue biopsy is not usually indicated unless there are areas of ulceration or localized erythroplakia (red patches). The differential diagnosis is with other causes of white lesions (see leukoplakia for a more complete discussion). Specific conditions which can produce a similar appearance include Darier's disease, discoid lupus erythematosus, oral candidiasis, and oral lichen planus.

If a biopsy is taken, the histopathologic appearance is one of hyperkeratosis and acanthosis. There may be squamous metaplasia of excretory ducts, which results in the visible papules if the ducts become hyperplastic. Neutrophils may fill some ducts. It is characterized as a "fissured" or "dried mud" appearance from excess keratin production by cells. Dysplasia is rarely seen.

Leukoedema is a harmless condition, and no treatment is indicated. People may be alarmed by the appearance and benefit from reassurance.

Immunoprecipitation, immunoblotting and enzyme-link immunosorbent assay (ELISA)

Poot et al. 2013 determined that immunoprecipitation for antibodies against envoplakin and periplakin or alpha2-macroglobulin-like–1 is the most sensitive test. However, alpha2-macroglobulin-like-1 can also be detected in patients with toxic epidermal necrosis.

Bullous Pemphigoid, Cicatricial Pemphigoid, Drug Eruptions. Epidermolysis Bullosa, Epidermolysis Bullosa Acquisita, Erythema Multiforme, Lichen Planus, pemphigus vulgaris, Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis.

PNP is most commonly mistaken for pemphigus vulgaris, due to the extreme similarities of the lesions that develop. However, the difference lies in the specificity of the autoreactive antibodies in each case.

The classification of exfoliative dermatitis into Wilson-Brocq (chronic relapsing), Hebra or pityriasis rubra (progressive), and Savill (self-limited) types may have had historical value, but it currently lacks pathophysiologic or clinical utility.

Generally, lichen nitidus is asymptomatic and self-limited; therefore, no treatment is required. However, if persistent pruritus is present, or the appearance “...interferes with daily activities or outlook...” topical glucocorticoids may be tried. If the disease process is symptomatic, generalized and extensive, oral glucocorticoids may be indicated. Other reported treatments include PUVA, UVA/UVB phototherapy, astemizole, acitretin, and etretinate.

When appears with sun/humidity; air conditioning (cool dry air) reduces swelling and discomfort.

When the appearance is caused by heat, the lesion is usually completely reversible within a few weeks if the smoking habit is stopped. This is the case even if the condition has been present for decades. Without stopping smoking, spontaneous remission of the lesion is unlikely. If the lesion persists despite stopping smoking, this is usually then considered to be a true leukoplakia rather than a reactionary keratotis, and may trigger the decision to carry out a biopsy to confirm the diagnosis. Since this condition almost always develops in the setting of long term heavy smoking, it usually indicates the need for regular observation for cancers associated with smoking, e.g. lung cancer.

Actinic granuloma (also known as "O'Brien granuloma") is a cutaneous condition characterized histologically by a dermal infiltrate of macrophages.

Actinic granuloma is an asymptomatic granulomatous reaction that affects sun-exposed skin, most commonly on the face, neck, and scalp.

It is characterized by annular or polycyclic lesions that slowly expand centrifugally and have an erythematous elevated edge and a hypopigmented, atrophic center.

Advise to reduce exposure to the sun and to use sunscreen.

Treatment with topical halometasone cream, pimecrolimus cream.

You have to treat the primary cause or the exacerbation may persisist and reincide.

Topical steroids are the primary category of medications used to treat exfoliative dermatitis (ED). A sedative antihistamine may be a useful adjunct for pruritic patients, since it helps patients to sleep at night, thus limiting nocturnal scratching and excoriations. Antimicrobial agents often are used if an infection is suspected to be precipitating or complicating exfoliative dermatitis. Other drugs specifically indicated for management of underlying cause of exfoliative dermatitis may be necessary.

Fiddler’s neck does not usually form unless the musician is practicing or playing for more than a few hours each day, and only seems to develop after a few years of serious playing. Thus, when not infected or otherwise problematic, fiddler’s neck may be known as a benign practice mark and may be worn proudly as an indication of long hours of practice. Blum & Ritter (1990) found that 62% of 523 professional violinists and violists in West Germany experienced fiddler’s neck, with the percentage among violists being higher (67%) than among violinists (59%). Viola players are believed to be more predisposed to developing fiddler’s neck than violinists because the viola is larger and heavier, but this has not been empirically confirmed.

The development of fiddler’s neck does not depend on preexisting skin problems, and Blum & Ritter find that only 23% of men and 14% of women in their study reported cutaneous disorders in other parts of the face (mainly acne and eczema) that were independent of playing the violin or viola. Fiddler’s neck may exacerbate existing acne, but acne may also be limited solely to the lesion and not appear elsewhere. Nonetheless, musicians with underlying dermatologic diseases like acne and eczema are more endangered by fiddler’s neck than others. Males may develop folliculitis or boils due to involvement of beard hair.

Vaccinating girls with HPV vaccine before their initial sexual contact has been claimed to reduce incidence of VIN.

The differential diagnosis includes oral lichen planus, erythematous candidiasis, leukoplakia, lupus erythematosus, glossitis, and chemical burns. Atrophic glossitis is usually distinguished from benign migratory glossitis on the basis of the migrating pattern of the lesions and the presence of a whitish border, features which are not present in atrophic glossitis, which instead shows lesions which enlarge rather than migrate. Rarely, blood tests may be required to distinguish from glossitis associated with anemia or other nutritional deficiencies. Since the appearance and the history of the condition (i.e. migrating areas of depapillation) are so striking, there is rarely any need for biopsy. When biopsy is taken, the histopathologic appearance is quite similar to psoriasis:

- Hyperparakeratosis.

- Acanthosis.

- Subepithelial T lymphocyte inflammatory infiltrate.

- Migration of neutrophilic granulocytes into the epithelial layer, which may create superficial microabscesses, similar to the Munro's microabscesses described in pustular psoriasis.

It is self limiting condition

1.reassurence

2.steriod cream for local application

3.moisterizer lotion

The histology of lichen nitidus is significant for a "...localized granulomatous lymphohistiocytic infiltrate in an expanded dermal papilla with thinning of overlying epidermis and downward extension of the ridges at the lateral margin of the infiltrate, producing a typical 'claw clutching a ball' picture..."

Treatment for fiddler’s neck is unnecessary if it is painless and shows minimal swelling, particularly since minor cases are taken as a mark of pride. But fiddler’s neck may lead to worse disorders. The primary methods of treatment involve adjustments to playing of the instrument:

- good hygiene for the affected area and for the instrument

- use of a clean cotton cloth that is changed frequently

- use of a shoulder rest to reduce pressure below the jaw

- a suitable chin rest, especially one carved or molded for the individual

- Covering or changing potentially allergenic materials on the instrument.

- shifting the chin rest to the center of the body over the tailpiece

- smoothing coarse surfaces to reduce abrasion

- for males, growing a beard to avoid folliculitis

Surgery is necessary for sialolithiasis, parotid tumors, and cysts. Cervical lymph nodes that are larger than 1 cm must be biopsied. Connective tissue can be removed by excision when a non-inflamed mass is large, and there is generally little recurrence. Infections should be treated conservatively, and causative species should be identified through smear and culture for appropriate antibiotic selection. Reduction of playing time may be helpful for cases without inflammation, but in 30% of cases this did not improve the symptoms.

The diagnosis can typically be made from the clinical appearance alone, but not always. As candidiasis can be variable in appearance, and present with white, red or combined white and red lesions, the differential diagnosis can be extensive. In pseudomembraneous candidiasis, the membranous slough can be wiped away to reveal an erythematous surface underneath. This is helpful in distinguishing pseudomembraneous candidiasis from other white lesions in the mouth that cannot be wiped away, such as lichen planus, oral hairy leukoplakia. Erythematous candidiasis can mimic geographic tongue. Erythematous candidiasis usually has a diffuse border that helps distinguish it from erythroplakia, which normally has a sharply defined border.

Special investigations to detect the presence of candida species include oral swabs, oral rinse or oral smears. Smears are collected by gentle scraping of the lesion with a spatula or tongue blade and the resulting debris directly applied to a glass slide. Oral swabs are taken if culture is required. Some recommend that swabs be taken from 3 different oral sites. Oral rinse involves rinsing the mouth with phosphate-buffered saline for 1 minute and then spitting the solution into a vessel that examined in a pathology laboratory. Oral rinse technique can distinguish between commensal candidal carriage and candidiasis. If candidal leukoplakia is suspected, a biopsy may be indicated. Smears and biopsies are usually stained with periodic acid-Schiff, which stains carbohydrates in fungal cell walls in magenta. Gram staining is also used as Candida stains are strongly Gram positive.

Sometimes an underlying medical condition is sought, and this may include blood tests for full blood count and hematinics.

If a biopsy is taken, the histopathologic appearance can be variable depending upon the clinical type of candidiasis. Pseudomembranous candidiasis shows hyperplastic epithelium with a superficial parakeratotic desquamating (i.e., separating) layer. Hyphae penetrate to the depth of the stratum spinosum, and appear as weakly basophilic structures. Polymorphonuclear cells also infiltrate the epithelium, and chronic inflammatory cells infiltrate the lamina propria.

Atrophic candidiasis appears as thin, atrophic epithelium, which is non-keratinized. Hyphae are sparse, and inflammatory cell infiltration of the epithelium and the lamina propria. In essence, atrophic candidiasis appears like pseudomembranous candidiasis without the superficial desquamating layer.

Hyperplastic candidiasis is variable. Usually there is hyperplastic and acanthotic epithelium with parakeratosis. There is an inflammatory cell infiltrate and hyphae are visible. Unlike other forms of candidiasis, hyperplastic candidiasis may show dysplasia.

Chronic ulcerative stomatitis is a recently discovered condition with specific immunopathologic features. It is characterized by erosions and ulcerations which relapse and remit. Lesions are located on the buccal mucosa (inside of the cheeks) or on the gingiva (gums). The condition resembles Oral lichen planus when biopsied.

The diagnosis is made with Immunofluorescence techniques, which shows circulating and tissue-bound autoantibodies (particulate stratified squamous-epithelium-specific antinuclear antibody) to DeltaNp63alpha protein, a normal component of the epithelium. Treatment is with hydroxychloroquine.

Leukoedema is common. It occurs in about 70-90% of black skinned adults and about 50% of black skinned children. The prevalence in white skinned people is considerably less, but reports range from less than 10% to more than 90%, probably varying depending upon the population studied, and the methods used in the study, e.g. examination conditions and the diagnostic criteria. The ethnic variation may be explained by genetic factors or simply because black skinned people have greater amount of melanin in the mucosa, making it appear darker (termed racial or physiologic pigmentation). This darker mucosa may make the edematous changes more noticeable, whereas in the mucosa of people with lighter skin types leukoedema gives a milder presentation.

Subacute cutaneous lupus erythematosus (SCLE) is a clinically distinct subset of cases of lupus erythematosus that is most often present in white women aged 15 to 40, consisting of skin lesions that are scaly and evolve as polycyclic annular lesions or plaques similar to those of plaque psoriasis.

Characteristically the lesions appear in sun-exposed areas such as the vee of the neckline or the forearms, but not the face. It may be brought on by sun-sensitizing medications, but is usually associated with autoimmune disorders such as rheumatoid arthritis and Sjögren's syndrome.

Treatment generally involves sun avoidance and protection and topical corticosteroids. Sometimes systemic drug treatment is necessary. Besides corticosteroids other immunosuppressants such as methotrexate are also used.

Lesions of SCLE may have an annular configuration, with raised red borders and central clearing.