Some Common Skin Diseases Of The Scalp
Seborrhoeic Dermatitis (Dandruff)
The cause of seborrhoeic dermatitis is unknown. There are two types of seborrhoeic dermatitis: (i) infantile seborrhoeic dermatitis (Fig. 1) - commonly seen in newborns and babies, (ii) adult seborrhoeic dermatitis - commonly seen in middle-aged adults.
Seborrhoeic dermatitis presents with yellowish, greasy scales on the scalp. The underlying scalp skin is red. In mild disease only patchy areas of the scalp are affected. In more severe cases, there may be diffuse scaliness and redness. Seborrhoeic dermatitis may affect the skin over the eyebrows, inner cheeks, chest, back and the groin. The condition may or may not be itchy. Seborrhoeic dermatitis is not a fungal infection although yeast infections have been reported to be associated with seborrhoeic dermatitis. Patients with HIV infection may develop very severe seborrhoeic dermatitis.
Treatment of seborrhoeic dermatitis consists of mild antiseptic or antifungal shampoos and mild topical steroid lotion or gel. The condition tends to be recurrent.
Psoriasis Of The Scalp
Psoriasis is an inflammatory skin disease characterized by an increased rate of skin cell turnover. It presents as plaques with thick scales appearing on the skin and scalp. The skin lesions appear as discrete scaly plaques on the scalp (Fig. 2) and along the hairline and often extend to the skin of the forehead and sides of the scalp (Fig. 3). The plaques are pink and covered by silvery scales. Psoriasis is usually non-itchy. Nail changes may occur.
Psoriasis of the scalp is treated with coal tar shampoo and coal tar ointment or topical steroid spray or gel.
Contact Dermatitis and Skin Allergies
Contact dermatitis is an inflammatory condition caused by an external agent. Irritant contact dermatitis of the scalp can occur from overuse of medicated shampoo, chemicals e.g. bleaching lotion, perm lotion and excessive heat applied to the scalp. Many topical preparations for hair and scalp can cause skin allergies. The commonest cause of allergic contact dermatitis of the scalp is hair dye allergy (Fig. 4). Other possible allergens are fragrance in hair lotion, chemical in perm lotion and medicaments/preservatives in shampoos and hair/scalp lotion.
Dermatitis presents as itchy scaly red patches on the scalp, hairline and ears. In the acute phase, vesicles and swelling may occur. Eyelid swelling may be seen.
You should consult your doctor if you have symptoms of contact dermatitis for treatment and investigations to ascertain the cause of the dermatitis. Preventive measures can be taken to prevent relapse. A patch test to ascertain the cause of allergy may be necessary.
Lichen planus is an inflammatory disorder of the skin, which can cause bald scarring patches on the scalp. The cause of lichen planus is unknown. On the scalp it starts off as a reddish purplish patch or plaque, which may enlarge with loss of hair (Fig. 5). On resolution, the affected skin is scarred and bald. The skin lesions are often itchy, and involvement of the oral mucosa and nails may be seen. On other parts of the body, lichen planus presents as bluish scaly patches, which are itchy. Lichen planus usually burns itself out spontaneously after a few years.
Lichen planus of the scalp should be treated early to prevent scarring and permanent balding. The treatment of choice is topical steroids or intralesional injection of steroids on the affected skin.
Discoid Lupus Erythematosus (DLE)
This is an autoimmune disease affecting predominantly the skin. It presents as bald, scaly red patches on the scalp. The skin is thinned out and prominent capillaries may be seen on the patches. Hair loss in these scarred patches are obvious and is often permanent (Fig. 6). The skin lesion is painless and not itchy. Other areas of the skin e.g. the face and ears are often affected. Such skin lesions are often sun-sensitive. Laboratory tests including a skin biopsy are required to confirm the diagnosis.
DLE should be treated immediately to prevent progressive scarring and balding of the scalp. There are effective treatments for the disease but scarred lesions are usually not responsive to treatment. Occasionally, the disease leading to a condition called systemic lupus erythematosus may affect the internal organs e.g. the lungs, kidneys and heart. Hence, regular check-up by your doctor is necessary if you suffer from DLE.
This is an autoimmune disease of the skin. The scalp is often affected. It presents as one or more bald patches on any part of the scalp. It is often not preceded by any redness or associated with itch. Bunches of hair just fall off suddenly over a few days leaving behind completely bald patches (Fig. 7). The underlying skin appears perfectly normal. The cause of alopecia areata is unknown. Most patients recover spontaneously after several months. In severe cases, the whole scalp may be affected leading to complete baldness. The disease is rarely associated with other skin disease e.g. thyroid disease.
Treatment consists of intralesional injections of steroid or painting the affected skin with chemicals that induces allergic reaction at regular intervals. You should consult your doctor for early treatment. Fig. 7 Smooth, non-scarring area of hair loss is seen. Fig. 6 A patch of scarring alopecia is seen. Fig. 5 Diffuse erythema of the scalp with areas of scarring alopecia. You should consult your doctor if you have symptoms of contact dermatitis for treatment and investigations to ascertain the cause of the dermatitis. Preventive measures can be taken to prevent relapse. A patch test to ascertain the cause of allergy may be necessary.
Naevus sebaceous are birthmarks originating from the oil glands of the skin. They are present at birth, initially as a faint yellowish patch that becomes raised and rough and wart-like as the child grows older (Fig. 1). It usually appears on the scalp, but can occur on the face and neck occasionally. The lesion is asymptomatic. It often enlarges at puberty, and there is a very small risk of cancer developing on the birthmarks during adulthood. Surgical removal is the treatment of choice.
Seborrhoeic Keratoses (Seborrhoeic Warts, Age Spots)
These are benign growths on the scalp or on any part of the body. They appear as discrete, sharply demarcated brownish to black patches (Fig. 2) or raised flat-topped lumps of various sizes. They have a smooth or rough surface. They usually occur in older adults and are very common in persons over 50 years old. The lesions often appear on the face, but some may occur on the scalp (Fig. 3). These lesions are benign and not associated with any symptoms. They do not need treatment.
The lesions can be destroyed and removed by liquid nitrogen applications, electrosurgery or shave excision or laser surgery for cosmetic reasons.
Solar keratoses are pre-cancerous skin lesions on sun-exposed skin of the face and scalp. On the scalp they occur on balding individuals where chronic sun exposure occurs (Fig. 4). They are often seen in fair skinned individuals who have had exposure to sunlight for many years. They often occur in middle-aged and older individuals. Solar keratoses present as ill-defined red scaly patches on the skin. The surface of the lesion looks and feel rough (akin to fine sandpaper). The lesion is painless and not itchy. If left untreated solar keratosis may develop into skin cancer.
Solar keratoses must be destroyed to stop cancerous transformation. It is usually destroyed with liquid nitrogen applications or topical anticancer cream e.g. 5-fluorouracil. Patients with solar keratoses must avoid further sun exposure. Patients should avoid mid-day sun exposure and use sunscreen cream daily. He should consult his doctor regularly to get treatment whenever new lesions occur. A skin biopsy may be necessary to ascertain if a cancer has developed.
This is a rare blood vessel cancer of the skin. It tends to appear on the scalp, face and ears (Fig. 5). It usually occurs in elderly patients, and it commonly presents as single or grouped bluish-red nodules or plaques on the scalp, face or ears. The lesions may occasionally be mildly tender but are often painless. Early diagnosis is essential to improve the prognosis of such patients. A skin biopsy is essential to confirm the diagnosis.
Patients with angiosarcoma are referred to the oncologist for treatment. Localised lesions can be removed by surgery, but large lesions need radiotherapy. The prognosis of angiosarcoma is poor generally.
Fungal Infection (Ringworm, Tinea Capitis)
Ringworm infection of the scalp is caused by a fungal infection. Ringworm infection of the scalp is more common in children than in adults. Fungal infection of the scalp presents in a variety of ways, depending on its severity and source of infection. In mild cases, the fungal infection appears as itchy scaly patches on the scalp. The hair follicles and hair are infected. The infected hairs are irregularly broken and fall off leaving bald patches (Fig. 6). The underlying skin may be red and inflamed. In severe infection (often infected from infected pets), the scalp skin becomes very red, tender and boggy. Pus may exude from the inflamed skin and boils/abscesses (called kerion) may form. Infected hair falls off and crusting may be present.
Fungal infections of the scalp can be effectively treated with oral antifungal drugs and good hair care. The source of infection e.g. pets should be treated simultaneously to prevent recurrence. Early recognition and treatment of the fungal infection will prevent permanent scaring and balding. Consult your doctor immediately if you suspect you have fungal infection of the scalp.
Bacteria Infections Of The Hair Follicles (Folliculitis, Boils)
Bacterial infection of the hair follicles causes folliculitis, or inflammation of the hair follicles/pores (Fig. 7). Folliculitis presents as pimple-like eruptions on the scalp. The small, discrete red lumps are painful and tender and are often scattered on different areas of the scalp. Pustules may be seen. Some individuals are more susceptible to such infection than others. If the infection becomes too frequent, tests should be carried out to ascertain if there is any abnormality in their immune system.
Folliculitis can be effectively treated with appropriate oral antibiotics. Good hygiene, regular washing of the scalp and hair with mild antiseptic shampoo will help prevent recurrences. Occasionally long term oral antibiotics may be necessary to suppress infections.
Shingles (Herpes Zoster)
Shingles is caused by a viral infection. This virus also causes chickenpox. Patients with shingles always have past chickenpox infection. Shingles represent a reactivation of the chickenpox virus. It is often seen in individuals with lower immunity e.g. following a viral infection, cancer, etc. The skin eruptions appear in a linear pattern following the distribution of a branch of the nerve. There is often preceding pain and itch just before the appearance of skin eruptions. It presents as a very painful blistering rash followed over the next week by erosions and crusting over affected areas of the skin e.g. on the forehead and anterior scalp, or the neck and back of the scalp (Fig. 8). The condition is self-limiting and should clear after about 2 weeks. However, severe pain may persist for months after the skin lesions have cleared. The elderly are at a higher risk of developing post herpetic neuralgia. Patients with shingles should see their doctor and may require investigation for any underlying cause of lowered immunity.
Shingles can be effectively treated if appropriate antiviral drugs are taken very early (within 48 hours of appearance of symptoms). Oral antiviral drugs can reduce the duration and severity of shingles. Consult your doctor immediately if you suspect you have shingles. Fig. 8 Vesicles, erosions and crusted areas seen affecting one side of face & scalp.