White piedra (or tinea blanca) is a mycosis of the hair caused by several species of fungi in the genus "Trichosporon". It is characterized by soft nodules composed of yeast cells and arthroconidia that encompass hair shafts.

Many conditions affect the human integumentary system—the organ system covering the entire surface of the body and composed of skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment. The skin weighs an average of four kilograms, covers an area of two square meters, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. The two main types of human skin are: glabrous skin, the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. Within the latter type, the hairs occur in structures called pilosebaceous units, each with hair follicle, sebaceous gland, and associated arrector pili muscle. In the embryo, the epidermis, hair, and glands form from the ectoderm, which is chemically influenced by the underlying mesoderm that forms the dermis and subcutaneous tissues.

The epidermis is the most superficial layer of skin, a squamous epithelium with several strata: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. Nourishment is provided to these layers by diffusion from the dermis, since the epidermis is without direct blood supply. The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells. Of these, keratinocytes are the major component, constituting roughly 95 percent of the epidermis. This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. In normal skin, the rate of production equals the rate of loss; about two weeks are needed for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum.

The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary dermis and the reticular dermis. The superficial papillary dermis with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. Structural components of the dermis are collagen, elastic fibers, and ground substance. Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing.

The subcutaneous tissue is a layer of fat between the dermis and underlying fascia. This tissue may be further divided into two components, the actual fatty layer, or panniculus adiposus, and a deeper vestigial layer of muscle, the panniculus carnosus. The main cellular component of this tissue is the adipocyte, or fat cell. The structure of this tissue is composed of septal (i.e. linear strands) and lobular compartments, which differ in microscopic appearance. Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source.

Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as dermatoses, as well as many nonpathologic states (like, in certain circumstances, melanonychia and racquet nails). While only a small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described. Classification of these conditions often presents many nosological challenges, since underlying etiologies and pathogenetics are often not known. Therefore, most current textbooks present a classification based on location (for example, conditions of the mucous membrane), morphology (chronic blistering conditions), etiology (skin conditions resulting from physical factors), and so on. Clinically, the diagnosis of any particular skin condition is made by gathering pertinent information regarding the presenting skin lesion(s), including the location (such as arms, head, legs), symptoms (pruritus, pain), duration (acute or chronic), arrangement (solitary, generalized, annular, linear), morphology (macules, papules, vesicles), and color (red, blue, brown, black, white, yellow). Diagnosis of many conditions often also requires a skin biopsy which yields histologic information that can be correlated with the clinical presentation and any laboratory data.

One approach involves shaving the affected areas. Another approach involves the use of antifungal medication.

Piedra (also known as "Trichosporosis") is a hair disease caused by a fungus.

Types include:

- White piedra

- Black piedra

Hair diseases are disorders primarily associated with the follicles of the hair.

A few examples are

- Alopecia

- Bubble hair deformity

- Hair casts

- Hair loss

- hypertrichosis

- Ingrown hair

- Monilethrix

- Premature greying of hair

- Pattern hair loss

- Trichorrhexis invaginata

Many hair diseases can be associated with distinct underlying disorders.

Piedra are fungal diseases.

Hair disease may refer to excessive shedding or baldness (or both). Balding can be localised or diffuse, scarring or non-scarring. Increased hair can be due to hormonal factors (hirsutism) or non-hormonal (hypertrichosis). Scalp disorders may or may not be associated with hair loss.

Black piedra is a form of piedra caused by "Piedraia hortae".

Terbinafine has been used in the treatment.

Parasitic infestations, stings, and bites in humans are caused by several groups of organisms belonging to the following phyla: Annelida, Arthropoda, Bryozoa, Chordata, Cnidaria, Cyanobacteria, Echinodermata, Nemathelminthes, Platyhelminthes, and Protozoa.

- "Acanthamoeba" infection

- Amebiasis cutis

- Ant sting

- Arachnidism

- Baker's itch

- "Balamuthia" infection

- Bedbug infestation (bedbug bite, cimicosis)

- Bee and wasp stings

- Blister beetle dermatitis

- Bombardier beetle burn

- Bristleworm sting

- Centipede bite

- Cheyletiella dermatitis

- Chigger bite

- Coolie itch

- Copra itch

- Coral dermatitis

- Creeping eruption (cutaneous larva migrans)

- Cutaneous leishmaniasis (Aleppo boil, Baghdad boil, bay sore, Biskra button, Chiclero ulcer, Delhi boil, Kandahar sore, Lahore sore, leishmaniasis tropica, oriental sore, "pian bois, uta")

- "Cysticercosis" cutis

- Demodex mite bite

- Dogger Bank itch

- Dracunculiasis (dracontiasis, guinea worm disease, Medina worm)

- Echinococcosis (hydatid disease)

- Elephantiasis tropica (elephantiasis arabum)

- Elephant skin

- Enterobiasis (oxyuriasis, pinworm infection, seatworm infection)

- "Erisipela de la costa"

- Feather pillow dermatitis

- Funnel web spider bite

- Gamasoidosis

- Gnathostomiasis (larva migrans profundus)

- Grain itch (barley itch, mattress itch, prairie itch, straw itch)

- Grocer's itch

- Head lice infestation (cooties, pediculosis capitis)

- Hookworm disease (ancylostomiasis, ground itch, necatoriasis, uncinariasis)

- Human trypanosomiasis

- Hydroid dermatitis

- Irukandji syndrome

- Jellyfish dermatitis

- Ked itch

- Larva currens

- Latrodectism (widow spider bite)

- Leech bite

- Leopard skin

- Lepidopterism (Caripito itch, caterpillar dermatitis, moth dermatitis)

- Lizard bite

- Lizard skin

- Loaiasis (Calabar swelling, fugitive swelling, "loa loa", tropical swelling)

- Loxoscelism (brown recluse spider bite, necrotic cutaneous loxoscelism)

- "Mal morando"

- Millipede burn

- Mosquito bite

- Mucocutaneous leishmaniasis (espundia, leishmaniasis americana)

- Myiasis

- Nairobi fly dermatitis (Kenya fly dermatitis, Nairobi eye)

- Nematode dermatitis

- Norwegian scabies (crusted scabies)

- Onchocerciasis

- Ophthalmia nodosa

- Paederus dermatitis

- Pediculosis corporis (pediculosis vestimenti, Vagabond's disease)

- Pediculosis pubis (crabs, phthirus pubis, pthirus pubis, pubic lice)

- Pneumocystosis (often classified as fungal)

- Portuguese man-of-war dermatitis

- Post-kala-azar dermal leishmaniasis (post-kala-azar dermatosis)

- Protothecosis

- Pulicosis (flea bites)

- Reduviid bite

- Scabies (itch mite infestation, seven-year itch)

- Scorpion sting

- Sea anemone dermatitis

- Seabather's eruption (sea lice)

- Sea urchin injury

- Seaweed dermatitis

- Snake bite

- Sowda

- Sparganosis

- Spider bite

- Stingray injury

- Swimmer's itch (cercarial dermatitis, schistosome cercarial dermatitis)

- Tarantula bite

- Tick bite

- Toxoplasmosis

- Trichinosis

- Trichomoniasis

- Tungiasis ("bicho de pie", chigoe flea bite, jigger bite, "nigua, pique")

- Visceral leishmaniasis (dumdum fever, "kala-azar")

- Visceral schistosomiasis (bilharziasis)

- Viscerotropic leishmaniasis

- Wheat warehouse itch