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

The dry scaling appearance is most noticeable during the winter as a result of dry air inside people's homes. During the summer, tanning of the surrounding normal skin makes the pale patches of pityriasis alba more prominent.

Individual lesions develop through 3 stages and sometimes are itchy:

1. Raised and red – although the redness is often mild and not noticed by parents

2. Raised and pale

3. Smooth flat pale patches

Lesions are round or oval raised or flat, of 0.5–2 cm in size although may be larger if they occur on the body (up to 4 cm), and usually number from 4 or 5 to over 20. The patches are dry with very fine scales. They most commonly occur on the face (cheeks), but in 20% appear also on the upper arms, neck, or shoulders.

The diagnostic differential should consider tinea and vitiligo amongst other causative factors.

The symptoms of this condition include:

- Occasional fine scaling of the skin producing a very superficial ash-like scale

- Pale, dark tan, or pink in color, with a reddish undertone that can darken when the patient is overheated, such as in a hot shower or during/after exercise. Tanning typically makes the affected areas contrast more starkly with the surrounding skin.

- Sharp border

Pityriasis versicolor is more common in hot, humid climates or in those who sweat heavily, so it may recur each summer.

The yeasts can often be seen under the microscope within the lesions and typically have a so-called "spaghetti and meatball appearance" as the round yeasts produce filaments.

In people with dark skin tones, pigmentary changes such as hypopigmentation (loss of color) are common, while in those with lighter skin color, hyperpigmentation (increase in skin color) is more common. These discolorations have led to the term "sun fungus".

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

Tinea versicolor is a condition characterized by a skin eruption on the trunk and proximal extremities. The majority of tinea versicolor is caused by the fungus "Malassezia globosa", although "Malassezia furfur" is responsible for a small number of cases. These yeasts are normally found on the human skin and become troublesome only under certain circumstances, such as a warm and humid environment, although the exact conditions that cause initiation of the disease process are poorly understood.

The condition pityriasis versicolor was first identified in 1846. Versicolor comes from the Latin, from "" to turn + color. It is also commonly referred to as Peter Elam's disease in many parts of South Asia.

The symptoms of this condition include:

- An upper respiratory tract infection may precede all other symptoms in as many as 69% of patients.

- A single, 2- to (rarely) 10-cm oval red "herald" patch appears, classically on the abdomen. Occasionally, the "herald" patch may occur in a 'hidden' position (in the armpit, for example) and not be noticed immediately. The "herald" patch may also appear as a cluster of smaller oval spots, and be mistaken for acne. Rarely, it does not become present at all.

- 7–14 days after the herald patch, many small (5–10 mm) patches of pink or red, flaky, oval-shaped rash appear on the torso. The more numerous oval patches generally spread widely across the chest first, following the rib-line in a characteristic "christmas-tree" distribution. Small, circular patches may appear on the back and neck several days later.

- In 6% of cases an "inverse" distribution may occur, with rash mostly on the extremities. In children, presentation can be atypical or inverse, and the course is typically milder.

- About one in four people with PR have mild to severe symptomatic itching. (Moderate itching due to skin over-dryness is much more common, especially if soap is used to cleanse the affected areas.) The itching is often non-specific, and worsens if scratched. This tends to fade as the rash develops and does not usually last through the entire course of the disease.

- The rash may be accompanied by low-grade fever, headache, nausea and fatigue.

Pityriasis alba is a common skin condition mostly occurring in children and usually seen as dry, fine-scaled, pale patches on the face. It is self-limiting and usually only requires use of moisturizer creams.

The condition is so named for the fine scaly appearance initially present (pityriasis) and the pallor of the patches that develop (while "alba" is Latin for white, the patches in this condition are not totally depigmented).

Cradle cap is seborrheic dermatitis that affects infants. It presents on the scalp as greasy patches of scaling, which appear thick, crusty, yellow, white or brown. The affected regions are not usually itchy and do not bother the child. Other affected areas can include the eyelids, ear, around the nose, and in the groin. Hair loss can also occur.

Pityriasis amiantacea (also known as "Tinea amiantacea") is an eczematous condition of the scalp in which thick tenaciously adherent scale infiltrates and surrounds the base of a group of scalp hairs. It does not result in scarring or alopecia.

Pityriasis amiantacea was first described by Alibert in 1832. Pityriasis amiantacea affects the scalp as shiny asbestos-like (amiantaceus) thick scales attached in layers to the hair shaft. The scales surround and bind down tufts of hair. The condition can be localised or covering over the entire scalp. Temporary alopecia and scarring alopecia may occur due to repeated removal of hairs attached to the scale. It is a rare disease with a female predilection.

Pityriasis amiantacea can easily be misdiagnosed due its close resemblance to other scalp diseases such as psoriasis, seborrhoeic dermatitis or lichen planus. However in pityriasis amiantacea the scales are attached to both the hair shaft and the scalp. Pityriasis amiantacea may be present with other inflammatory conditions such as atopic dermatitis or seborrhoeic dermatitis and sebaceous scales and alopecia can occur. According to the dermatology text Bolognia this condition is most often seen in psoriasis, but may also be seen in secondarily infected atopic dermatitis, seborrheic dermatitis, and tinea capitis.

Pityriasis lichenoides is a form of pityriasis.

Types include:

- Pityriasis lichenoides et varioliformis acuta

- Pityriasis lichenoides chronica

The bacteria staphylococci are present in the majority of cases. Treatment with systemic antibiotics and coal tar shampoo can completely clear the condition when Staphylococcus aureus bacteria are found. Fungal infections such as tinea capitis are known to mimic the symptoms of the condition and can be cleared with antifungal treatment.

Pityriasis rosea is a type of skin rash. Classically, it begins with a single red and slightly scaly area known as a "herald patch". This is then followed, days to weeks later, by a pink whole body rash. It typically lasts less than three months and goes away without treatment. Sometime a fever may occur before the start of the rash or itchiness may be present, but often there are few other symptoms.

While the cause is not entirely clear, it is believed to be related to human herpesvirus 6 (HHV6) or human herpesvirus 7 (HHV7). It does not appear to be contagious. Certain medications may result in a similar rash. Diagnosis is based on the symptoms.

Evidence for specific treatment is limited. About 1.3% of people are affected at some point in time. It most often occurs in those between the ages of 10 and 35. The condition was described at least as early as 1798.

Cradle cap is a yellowish, patchy, greasy, scaly and crusty skin rash that occurs on the scalp of recently born babies. It is usually not itchy and does not bother the baby. Cradle cap most commonly begins sometime in the first three months but can occur in later years. Similar symptoms in older children are more likely to be dandruff than cradle cap. The rash is often prominent around the ear, the eyebrows or the eyelids. It may appear in other locations as well, where it is called seborrhoeic dermatitis rather than cradle cap. Some countries use the term "pityriasis capitis" for cradle cap. It is extremely common, with about half of all babies affected. Most of them have a mild version of the disorder. Severe cradle cap is rare.

Tinea nigra (also known as "superficial phaeohyphomycosis," and "Tinea nigra palmaris et plantaris") is a superficial fungal infection that causes dark brown to black painless patches on the palms of the hands and the soles of the feet.

Pityriasis rotunda (also known as "Pityriasis circinata" and "Tinea circinata") is a disorder of keratisation of the skin that manifests as a perfectly circular, scaly patches on the torso and proximal portions of the extremities. It may be associated with diseases like hepatocellular carcinoma in racially predisposed groups.

Infections on the body may give rise to typical enlarging raised red rings of ringworm. Infection on the skin of the feet may cause athlete's foot and in the groin, jock itch. Involvement of the nails is termed onychomycosis, and they may thicken, discolour, and finally crumble and fall off. They are common in most adult people, with up to 20% of the population having one of these infections at any given moment.

Animals such as dogs and cats can also be affected by ringworm, and the disease can be transmitted between animals and humans, making it a zoonotic disease.

Specific signs can be:

- red, scaly, itchy or raised patches

- patches may be redder on outside edges or resemble a ring

- patches that begin to ooze or develop blister

- bald patches may develop, when the scalp is affected

- nails may thicken, discolour or begin to crack

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

A papulosquamous disorder is a condition which presents with both papules and scales, or both scaly papules and plaques.

Examples include psoriasis, lichen planus, and pityriasis rosea.

Occurring at any age these lesions appear as raised pink-red ring or bulls-eye marks. They range in size from . The lesions sometimes increase size and spread over time and may not be complete rings but irregular shapes. Distribution is usually on the thighs and legs but can also appear on the upper extremities, areas not exposed to sunlight, trunk or face. Currently EAC is not known to be contagious, but as many cases are incorrectly diagnosed as EAC, it is difficult to be certain.

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.

Fungi thrive in moist, warm areas, such as locker rooms, tanning beds, swimming pools, and skin folds; accordingly, those that cause dermatophytosis may be spread by using exercise machines that have not been disinfected after use, or by sharing towels, clothing, or footwear, such as rental bowling shoes, ski boots, ice skates or roller skates.

Erythroderma is generalized exfoliative dermatitis, which involves 90% or more of the patient's skin. The most common cause of erythroderma is exacerbation of an underlying skin disease, such as psoriasis, contact dermatitis, seborrheic dermatitis, lichen planus, pityriasis rubra pilaris or a drug reaction. Primary erythroderma is less frequent and is usually seen in cases of cutaneous T-cell lymphoma, in particular in Sézary's disease.

The most common causes of exfoliative dermatitis are best remembered by the mnemonic device ID-SCALP. The causes and their frequencies are as follows:

- Idiopathic - 30%

- Drug allergy - 28%

- Lymphoma and leukemia - 14%

- Atopic dermatitis - 10%

- Psoriasis - 8%

- Contact dermatitis - 3%

- Seborrheic dermatitis - 2%

Differential diagnosis in patients with erythroderma may be difficult.

This disease in humans is usually caused by "Demodex folliculorum" (not the same species affecting dogs) and is usually called demodicosis which may have a rosacea-like appearance. Common symptoms include hair loss, itching and inflammation. An association with pityriasis folliculorum has also been described.

Demodicosis is most often seen in folliculitis (inflammation of the hair follicles of the skin). Depending on the location it may be a small pustules (pimples or pustules) at the exit of hair, placed on inflamed, congested skin. Demodicosis is accompanied by itching, swelling and erythema of the eyelid margins, the appearance of scales at the base of the eyelashes. Typically, patients complain of eyestrain. Characteristic of view of the affected century: plaque on the edge of the eyelids, eyelashes stuck together, surrounded by crusts as a clutch.

Pityriasis lichenoides chronica is an uncommon, idiopathic, acquired dermatosis, characterized by evolving groups of erythematous, scaly papules that may persist for months.

Erythema anulare centrifugum (EAC), also known as deep gyrate erythema, erythema perstans, palpable migrating erythema and superficial gyrate erythema, is a descriptive term for a class of skin lesion presenting redness (erythema) in a ring form ("anulare") that spreads from a center ("centrifugum"). It was first described by Darier in 1916. Many different terms have been used to classify these types of lesions and it is still controversial on what exactly defines EAC. Some of the types include annular erythema (deep and superficial), erythema perstans, erythema gyratum perstans, erythema gyratum repens, darier erythema (deep gyrate erythema) and erythema figuratum perstans.