Chapter III - Dermatology

COMMON SKIN CONDITIONS AND PATHOLOGY

Hope, by far you must have known a little more about our skin, its functions, its use, its anatomy and physiology. There is still much to know and much to write about but we will first make a quick note of some of the common skin conditions and diseases that come across during routine transcription.

So lets now have a sneak preview of some of the few pathological conditions of the skin.

COMMON SKIN CONDITIONS AND PATHOLOGY

Albinism
Albinism is a genetic and/or hereditary pig­ment disorder in which melanocytes, cells that produce chemical called melanin and that are responsible for giving color to the skin, are present but they do not produce melanin. Characteristics of people with this disorder are white hair, pale, very light skin and pink eyes. Because of improper melanin formation, such individuals are very susceptible to skin cancers as skin and melanic act as an ultraviolet light filter for the body. Though medical science has advanced, but for albinism there is no medical treatment available still.

Basal cell and squamous cell carcinoma:
Basal cell carcinoma is the most prevalent type of skin malignancy. It arises from the malignancy of the basal cell layer of the lowest part of epidermis. Exces­sive exposure to sun's ultraviolet rays is the most common cause of basal cell carcinoma. It may appear as a skin sore or firm lump that does not heal. Basal cell carcinoma progress slowly and hence, is readily cur­able if detected early. Squamous cell carci­noma originates in the cells that form the skin's outer surface. It may appear as a scaly or crusty patch that may develop most often on the rim of the ear, mouth, or scalp. Squamous cell carcinoma can sometimes also in­vade nearby organs.

Decubitus ulcers (bed sores, pressure sores)
People who are bedridden, confined to the wheelchair, lacking sensation because of paralysis, and who cannot or do not change their posi­tions every few hours, their blood flow is reduced consequent to prolonged pressure. This results in cell death, skin thickening, consequently leading to blis­ters and open sores and, finally to skin ulceration called bedsores or pressure sores. These ulcers occur mostly at places where the bone is close to the skin, such as heels, ankle, hip, shoulder, elbow, and base of the spine. Advance bedsores may require debridement to remove dead tissue, whereas in early stages, they can be treated with spe­cial gels or antibiotics.

Eczema
Eczema is an inflammatory skin disease with lesions that may be erythematous, scaly, blis­tering, thickened, crusty, oozing, or itchy. These symptoms may exist in combination or singly. Anti-inflammatories are often pre­scribed in their treatment. Topical medications may include coal tar and a cortisone cream, hydrocortisone. If bacterial infection has set in as a result of scratching, then an­tibiotics may be prescribed.

Impetigo
Impetigo is a contagious skin infection caused by either staphylococcal or strepto­coccal bacteria, characterized by many small, isolated, itchy blisters, some of which may contain pus. When these blisters break, a characteristic yellow crust forms. Diagnosis can be made by inspecting the lesions and confirmed by scraping off a sample of cells from the sores for laboratory exam. Impetigo is most common among in infants and children. This infection in early stages affects only a small area and hence, can be treated with topical antibiotic ointments, such as mupirocin (Bactroban). In certain cases, oral antibiotics like penicillin and cephalosporins may be prescribed.

Kaposi’s sarcoma
Kaposi’s sarcoma is a cancer in which malignant cells appear as red and purple patches under the skin or mucous membranes. The lesions of Kaposi’s sarcoma originate mostly on the leg and then may spread to lungs, liver, intestinal tract, or lymph nodes. The skin le­sions themselves are painful. They can be accompanied by swelling, edema, and low-grade fever.

Melanoma
Melanoma is most lethal form of cancerous growth. It develops when the melanocytes (pigment cells) undergo malignant changes. Melanoma can frequently me­tastasize to other organs such as liver, brain, lungs, and other internal organs. Sunlight exposure is considered to be a leading con­tributing factor of this disease. Surgery is the most effective treatment for this disease. Chemotherapy and radiation therapy are used in addition to surgery to treat mela­noma.

Miliaria
Miliaria, also known as heat rash or prickly heat, is a skin condition characterized by clusters of tiny blisters filled with perspira­tion, mostly on the armpits and groin, sometimes also on chest, waist, and back. These blisters are formed when pores become blocked and sweat cannot be released from them. The heat rash is itchy. Remedies that alleviate itching and cool the skin work well for miliaria.

Pruritus
Pruritus is an itching sensation in the skin. It can be caused by a number of local factors ranging from insect bites, allergic reaction, dry skin, eczema to infectious diseases, or systemic problems.

Psoriasis
Psoriasis is a chronic skin disorder in which patches of skin become red and covered with dry silvery scales. The skin makes new cells so fast with psoriasis that they form silvery scales. The psoriatic patches form initially on the scalp, behind the ears, on the back of neck, on the elbows and knees, and near the nails of fingers and toes. The cause of psoriasis is unknown. In some cases, psoriasis is characterized by blisters usually on palms, and soles and is called pustular psoriasis.

Purpura
Any vascular bleeding disorder characterized by hemorrhage in the tissue, particularly be­neath skin tissue and showing up as bruises, ranging from tiny reddish or purplish spots called petechia to large hemorrhagic patches called ecchymosis is called pur­pura. Most types of vascular bleedings or purpuras are due to temporary change in the blood composition of platelets or rupturing of blood vessel walls because of deterioration of tissue making the vessel wall. Several types of purpura are purpura simplex (mostly hereditary), senile purpura (due to aging), aller­gic purpura (due to allergy), and idiopathic cytopenic purpura. Acute idiopathic cytopenic purpura affects children and follows a viral infection that has a reduced number of plate­lets, which are instrumental in blood clotting. Chronic idiopathic thrombocytic purpura af­fects mostly women in the age group 20-40 and is an autoimmune disorder in which plate­lets are destroyed.

Scabies
Scabies is a contagious, intensely itchy and highly infectious parasitic skin disease caused by itch mite, Sarcoptes scabiei. The mite is most often transferred by direct skin contact, especially during sexual activity, and less of­ten by indirect contact like sharing clothing or a towel. The female mite looks for places in skin, which are thickest, especially at the palms and soles to reproduce. It burrows a tunnel under the skin in which she deposits her eggs. Larvae hatch within 2 to 4 days. The charac­teristic itchy rash is caused perhaps due to hy­persensitivity to eggs, or waste products or mites and larvae. Potent parasite-killer medi­cations like gamma benzene hexachloride and lindane are used to destroy mites and their eggs. However, nowadays, milder but equally effective drugs such as permethrin are used.

Skin lesions
Lesions are the pathological conditions re­sulting from a wound or injury. Primarily, the skin lesions can be classified into the following

· Macule: A circumscribed lesion of any size, which is flat and discolored and which is nonpalpable.
· Papule: A small, solid, raised skin lesion less than 1 cm in size.
· Nodule: Palpable raised skin lesion, 1-2 cm in diameter that is larger than pap­ule
· Vesicle: Elevated skin lesion that con­tains fluid, less than 0.5 cm.
· Bulla: Elevated lesion containing fluid greater than 0.5 cm; blisters containing clear fluid. Pustule: Elevated skin lesion contain­ing pus; abscess.
· Tumor: Elevated skin lesion greater than 2 cm in diameter.
· Scale: Excessive dry exfoliation from the upper layer of skin.
· Wheal: A raised, red lesion, usually ac­companied by itching.
· Fissure: Small break in epidermis, arack-like sore exposing the dermis.
· Ulcer: Lesion caused on the surface of the skin or mucosa caused by superficial loss of tissues accompanied by in­flammation.

Tinea (Ringworm Infection)
Tinea is any fungal skin infection, caused by dermatophytes. The name of the fungus indicates the body part it affects. The fungi can infect the scalp (Tinea calpitis), the beard (Tinea barbae), the skin (Tinea corporis), the groin area (Tinea cruris), the feet (Tinea pedis a.k.a. athlete foot), or fingernails or toenails (Tinea unguium). Tinea infections can be identified by the distinctive appear­ance of their lesions. As they most often produce round lesions, hence, the name ring­worm. Most Tinea infections can be treated with antifungal drugs like clotrimazole, nystatin, and miconazole.

Urticaria (Hives)
Urticaria is an allergic skin disorder, characterized raised pink or pale red lesions with a flat top. Hives are warm and itchy to touch and normally range in size from one-fourth of inch to 1-1/2 inch. Hives are most often caused by food allergies. They can also de­velop in response to certain drugs, such as penicillin, aspirin, etc; or in response to con­tact with insect bites, cats, exposure to de­tergents or dry cleaning chemicals on clothes. Skin tests performed by an allergist can help in identifying the substance responsible for hives. Hives usually disappear on their own within one to seven days. To alleviate the symptoms, itching, antihistamines, such as diphenhydramine, hydroxyzine, and cyproheptadine are prescribed. In severe cases, corticoster­oids, such as prednisone may be prescribed.

Vitiligo
Vitiligo is a pigment disorder characterized by area of hypopigmentation, which develop when melanocytes are damaged. Hypopigmentation may range from small patches to large sections that cover most of the body. Combination of drug and light therapy is used, in which a drug is ad­ministered and followed by exposure to the ultraviolet light. This drug is activated by light and stimulates re-pigmentation by in­creasing the availability of melanocytes at skin surface. If vitiligo consists of only small, scattered patches, drugs to stimulate pig­mentation may be applied directly to the af­fected skin and areas then exposed to the sunlight. In those with vitiligo covering more than half the body, depigmentation is done by bleaching the rest of the skin.

Warts
Warts are epidermal growths caused by strains of HPV (human papilloma virus), which infect the epithelial cells of skin and then prompt them to multiply. The virus can spread abnormally and very fast from one person to another by direct contact. Veruccae vulgaris, the most prevalent form, develops on fingers, elbows, face and knees. Other types of warts are filiform, flat, pedun­culated, periungual, plantar, venereal, and laryngeal. Majority of the warts are benign. Warts can be quickly removed by burning them with electrocautery, laser surgery, cryosurgery, but about one-third may recur.

A many of the common skin pathology has been covered above. So now lets learn about a few of the common and widely performed skin procedures in the next chapter.