Physicians can often diagnose keratosis pilaris simply by examining the skin; tests are usually not needed. However, a dermatologist can use dermoscopy to confirm the diagnosis and assess if a person with KP is responding to treatment. Physicians will often consider family history and the presence of symptoms when making the diagnosis. Those with this condition are generally encouraged to contact a physician if the bumps are bothersome and do not improve with over the counter lotions.

Tinea versicolor may be diagnosed by a potassium hydroxide (KOH) preparation and lesions may fluoresce copper-orange when exposed to Wood's lamp.

The differential diagnosis for tinea versicolor infection includes:

- Progressive macular hypomelanosis

- Pityriasis alba

- Pityriasis rosea

- Seborrheic dermatitis

- Erythrasma

- Vitiligo

- Leprosy

- Syphilis

- Post-inflammatory hypopigmentation

The patches of pityriasis alba may last from 1 month to about one year, but commonly on the face last a year. However it is possible that the white patches may last for more than 1 year on the face.

There are several different types of keratosis pilaris, including "keratosis pilaris rubra" (red, inflamed bumps which can be on arms, head, legs), "keratosis pilaris alba" (rough, bumpy skin with no irritation), "keratosis pilaris rubra faceii" (reddish rash on the cheeks), and related disorders. Keratosis pilaris is commonly described in association with other dry skin conditions, such as ichthyosis vulgaris, xerosis and atopic dermatitis, including those of asthma and allergies.

Keratosis pilaris does not bear any known, long-term health implications, nor is it associated with increased mortality or morbidity. It is not related to goose bumps, which results from muscle contractions, except that both occur in the area where the hair shaft exits the skin.

In most patients, the condition lasts only a matter of weeks; in some cases it can last longer (up to six months). The disease resolves completely without long-term effects. Two percent of patients have recurrence.

No treatment is required and the patches in time will settle.

The redness, scale and itch if present may be managed with simple emollients and sometimes hydrocortisone, a weak steroid, is also used.

As the patches of pityriasis alba do not darken normally in sunlight, effective sun protection helps minimise the discrepancy in colouration against the surrounding normal skin. Cosmetic camouflage may be required.

Tacrolimus has been reported as speeding resolution.

In exceptionally severe cases PUVA therapy may be considered.

Experienced practitioners may make the diagnosis clinically. If the diagnosis is in doubt, tests may be performed to rule out similar conditions such as Lyme disease, ringworm, guttate psoriasis, nummular or discoid eczema, drug eruptions, other viral exanthems.The clinical appearance of pityriasis rosea is similar to that of secondary syphilis, and rapid plasma reagin testing should be performed if there is any clinical concern for syphilis. A biopsy of the lesions will show extravasated erythrocytes within dermal papillae and dyskeratotic cells within the dermis.

A set of validated diagnostic criteria for pityriasis rosea is as follows:

A patient is diagnosed as having pityriasis rosea if:

1. On at least one occasion or clinical encounter, he / she has all the essential clinical features and at least one of the optional clinical features, and

2. On all occasions or clinical encounters related to the rash, he / she does not have any of the exclusional clinical features.

The essential clinical features are the following:

1. Discrete circular or oval lesions,

2. Scaling on most lesions, and

3. Peripheral collarette scaling with central clearance on at least two lesions.

The optional clinical features are the following:

1. Truncal and proximal limb distribution, with less than 10% of lesions distal to mid-upper-arm and mid-thigh,

2. Orientation of most lesions along skin cleavage lines, and

3. A herald patch (not necessarily the largest) appearing at least two days before eruption of other lesions, from history of the patient or from clinical observation.

The exclusional clinical features are the following:

1. Multiple small vesicles at the centre of two or more lesions,

2. Two or more lesions on palmar or plantar skin surfaces, and

3. Clinical or serological evidence of secondary syphilis.

To help with cradle cap, parents can gently massage their baby's scalp with their fingers or a soft brush to loosen the scales. They may want to shampoo the baby's hair more frequently (no more than once a day), and after shampooing gently brush the baby's scalp with a soft brush or a terrycloth towel. Oil remedies can be used by rubbing a small amount of pure, plant-derived oil (coconut oil, pure olive oil, almond oil) on the baby's scalp and leaving it on for 15 minutes. After 15 minutes, gently comb out the flakes with a fine tooth comb or brush. Be sure to wash out all of the oil to avoid making the cradle cap worse.

For infants: in cases that are related to fungal infection, such as Tinea capitis, doctors may recommend a treatment application of clotrimazole (commonly prescribed for jock itch or athlete's foot) or miconazole (commonly prescribed for vaginal yeast infections).

For toddlers: doctors may recommend a treatment with a mild dandruff shampoo such as Selsun Blue or Neutrogena T-gel, even though the treatment may cause initial additional scalp irritation. A doctor may instead prescribe an antifungal soap such as ketoconazole (2%) shampoo, which can work in a single treatment and shows significantly less irritation than over-the-counter shampoos such as selenium disulfide shampoos, but no adequate and controlled study has been conducted for pediatric use as of 2010.

For adults: see the article on seborrheic dermatitis (the adult version of cradle cap).

A skin biopsy can be performed to test for EAC; tests should be performed to rule out other possible diseases such as: pityriasis rosea, tinea corporis, psoriasis, nummular eczema, atopic dermatitis, drug reaction, erythema migrans and other rashes.

For demodectic mange, properly performed deep skin scrapings generally allow the veterinarian to identify the microscopic mites. Acetate tape impression with squeezing has recently found to be a more sensitive method to identify mites. It was originally thought that because the mite is a normal inhabitant of the dog's skin, the presence of the mites does not conclusively mean the dog suffers from demodex. Recent research, however, found that demodex mite can hardly be found on clinically normal dogs, meaning that the presence of any number of mites in a sample is very likely to be significant. In breeds such as the West Highland White Terrier, relatively minor skin irritation which would otherwise be considered allergy should be carefully scraped because of the predilection of these dogs to demodectic mange. Skin scrapings may be used to follow the progress of treatment in demodectic mange.

Alternatively, plasma levels of zinc and copper have been seen to be decreased in dogs suffering with demodicosis. This may be due to inflammation involved in the immune response of demodicosis which can lead to oxidative stress resulting in dogs suffering from demodicosis to exhibit higher levels of antioxidant productivity. The catalases involved in the antioxidant pathway require the trace minerals zinc and copper. Dogs with demodicosis show a decrease in plasma copper and zinc levels due to the increased demand for antioxidant activity. Therefore, this may be considered as a potential marker for demodicosis.

Treatments for tinea versicolor include:

- Topical antifungal medications containing selenium sulfide are often recommended. Ketoconazole (Nizoral ointment and shampoo) is another treatment. It is normally applied to dry skin and washed off after 10 minutes, repeated daily for two weeks. Ciclopirox (Ciclopirox olamine) is an alternative treatment to ketoconazole, as it suppresses growth of the yeast "Malassezia furfur". Initial results show similar efficacy to ketoconazole with a relative increase in subjective symptom relief due to its inherent anti-inflammatory properties. Other topical antifungal agents such as clotrimazole, miconazole, terbinafine, or zinc pyrithione can lessen symptoms in some patients. Additionally, hydrogen peroxide has been known to lessen symptoms and, on certain occasions, remove the problem, although permanent scarring has occurred with this treatment in some sufferers. Clotrimazole is also used combined with selenium sulfide.

- Oral antifungals including ketoconazole or fluconazole in a single dose, or ketoconazole for seven days, or itraconazole can be used. The single-dose regimens, or pulse therapy regimens, can be made more effective by having the patient exercise 1–2 hours after the dose, to induce sweating. The sweat is allowed to evaporate, and showering is delayed for a day, leaving a film of the medication on the skin.

Typical medical advice is to use diluted baby shampoo on a cotton swab to cleanse the eyelid. There is no agreement on the dilution, which ranges from a few drops to a half cup warm water, to a 50/50 mix.

It is not contagious and currently there is no cure for the disease, although the lesions can be treated with ultraviolet therapy as well as topical steroids and antibiotics.

Treatment often involves multiple therapies that address the immune system and bacterial, viral, or dermatological causes.

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.

Diagnosis of tinea nigra causing fungus is made on microscopic examination of skin scrapings, mixed with potassium hydroxide (KOH). The KOH the nonfungal debris.

No treatment is usually needed as they usually go away anywhere from months to years. The lesions may last from anywhere between 4 weeks to 34 years with an average duration of 11 months. If caused by an underlying disease or malignancy, then treating and removing the disease or malignancy will stop the lesions. It usually doesn't require treatment, but topical corticosteroids may be helpful in reducing redness, swelling and itchiness.

Some supported and not supported methods of having an effect on EAC include:

- Photosensitive so it can be moved/reduced with appropriate sunlight.

- Vitamin D

- Immune system - hence it will increase in size/number when the immune system is low or overloaded.

- Hormone Drugs

- Disulone

- Stress reduction

- Topical calcipotriol - a topical vitamin D derivative has been known to be beneficial

Treatment consists of topical application of dandruff shampoo, which contains selenium sulfide, over the skin. Topical antifungal imidazoles may also be used, such as ketoconazole. This is the same treatment plan for tinea or pityriasis versicolor.

There is no standard treatment for PLC. Treatments may include ultraviolet phototherapy, topical steroids, sun exposure, oral antibiotics, corticosteroid creams and ointments to treat rash and itching.

One study identified the enzyme bromelain as an effective therapeutic option for PLC.

In cases of extensive vitiligo the option to de-pigment the unaffected skin with topical drugs like monobenzone, mequinol, or hydroquinone may be considered to render the skin an even colour. The removal of all the skin pigment with monobenzone is permanent and vigorous. Sun-safety must be adhered to for life to avoid severe sunburn and melanomas. Depigmentation takes about a year to complete.

Types include:

- Pityriasis alba

- Pityriasis lichenoides chronica

- Pityriasis lichenoides et varioliformis acuta

- Pityriasis rosea

- Pityriasis circinata

- Pityriasis rubra pilaris

- Pityriasis versicolor

- Dandruff, historically called "Pityriasis capitis"

- Pityriasis amiantacea

Advice often given includes:

- Avoid sharing clothing, sports equipment, towels, or sheets.

- Wash clothes in hot water with fungicidal soap after suspected exposure to ringworm.

- Avoid walking barefoot; instead wear appropriate protective shoes in locker rooms and sandals at the beach.

- Avoid touching pets with bald spots, as they are often carriers of the fungus.

In mild cases, vitiligo patches can be hidden with makeup or other cosmetic camouflage solutions. If the affected person is pale-skinned, the patches can be made less visible by avoiding tanning of unaffected skin.

It is commonly misdiagnosed as chickenpox or rosacea. Pleva is also often misidentified as a form of staph. The most accurate way to diagnose it is by biopsy. This disease has not been known to be life-threatening. However, there may be mutations of the disease that can cause ulcers on the exterior.

Pityriasis commonly refers to flaking (or scaling) of the skin. The word comes from the Greek πίτυρον "bran".

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.