The human integumentary system consists of skin---the body's single largest organ---and derivatives of the skin, including toenails and fingernails, oil and sweat glands and hair, according to MedlinePlus. Most of the diseases that affect the integumentary system are dermatological and include such specific skin disorders or diseases as acne, psoriasis, athlete's foot, dermatitis, vitiligo and skin cancer. Diseases that affect the hair and nails include alopecia areata and paronychia.
Acne and Psoriasis
Acne, the most common skin disease, is seen most often in adolescence and can be either inflammatory or noninflammatory. The former is characterized by inflamed red pimples on the face, back and chest, while noninflammatory acne appears as whiteheads or blackheads. All acne pimples begin the same way, according to Acne.com, with a "comedo, an enlarged hair follicle plugged with oil and bacteria." Psoriasis is a chronic skin condition in which the body's immune system triggers an abnormally rapid skin cell growth cycle. The most common physical characteristics of the disease are raised red lesions that are covered by a scaly, silvery buildup of dead skin cells.
Dermatitis and Athlete's Foot
Dermatitis is a broad term that covers a wide variety of inflammatory skin conditions, almost all of which begin as an allergic reaction to a specific substance with which the skin comes in contact. The result is usually an itchy rash that is red or pink in color. Eczema is a form of dermatitis. Athlete's foot is a fungal infection that occurs most frequently between the toes. The proper medical term for athlete's foot is tinea pedis.
Vitiligo is a skin condition in which the loss of pigment results in the appearance of irregularly shaped, milky white-colored patches on the skin, according to an article by Oliver Pichay on NursingCrib.com. For obvious reasons, this condition is far easier to spot in people whose normal skin color is dark.
The most widely diagnosed cancer of all, skin cancer comes in a variety of forms, with basal cell carcinoma, squamous cell carcinoma and melanoma being the three most often seen. While both basal and squamous cell cancers are slow to spread and easily treated, melanoma is far more serious and is responsible for a high number of deaths each year.
This condition, which may be caused in part by some dysfunction in the autoimmune system, causes the loss of hair in patches. Sometimes the condition results in a total loss of hair. Treatment with ultraviolet light therapy, steroidal injections and topical application of corticosteroids may slow the advance of this disorder, but no fully effective remedy has yet been found.
Paronychia is an infection that develops in the soft tissue at the base of fingernails. It occurs in both acute and chronic forms and usually develops when the area between the base of the nail and the adjacent soft tissue is invaded by a bacterium or fungus. The affected soft tissue is usually very tender and sore to the touch.