The epidermis consists mainly of a stratified squamous keritanized epithelium. From the dermis outward, the epidermis consists of five layers of keratin-producing cells. The stratum basale (stratum germinativum) consists of a single layer of columnar or cuboidal cells resting on the basal lamina at the dermal- epidermal junction. The stratum spinosum consists of cuboidal, polygonal, or slightly flattened cells covered with desmosomes. These filaments are thought to play a role in maintaining cohesion among cells and resisting the effects of abrasion.
All the mitosis is confined to the malpighian layer which consists of the stratum basale and the stratum spinosum. The stratum granulosum is characterized by 3 - 5 layers of flattened polygonal cells. Their cytoplasm if filled with coarse basophilic granules called keratohyalin granules. The cells of this layer produce a substance that acts as a barrier to penetration of foreign materials and provides an important sealing effect in the skin. The stratum lucidum, which is more apparent in thick skin, is composed of a thin layer of flattened eosinophilic cells. The stratum corneum consists of 15 - 20 layers of flattened nonnucleated keratinized cells. After keratinization, the cells consist of only fibrillar and amorphous proteins and thickened plasma membranes; thus they are called horny cells. Renewal of the epidermis under normal conditions occurs every 15 - 30 days and is due to the mitotic activity in the germinativum and spinosum layers. Other cells within the epidermis include melanocytes, Langerhans' cells, and Merkel's cells. Eumelanin is a dark brown pigment produced by the melanocytes which are found beneath or between the cells of the stratum basale and in the hair follicles. They are derived from neural crest cells and produce melanin. Once formed, melanin is transferred to the cells of the germinativum and spinosum layers through the melanocyte's cytoplasmic extensions. The ratio of melanocytes to basal cells is 1 to 5 on the face and 1 to 20 on covered sites of the body.
The differences in skin color are due mainly to differences in the number of melanin granules in the keratinocytes. Langerhans' cells (star-shaped) are found mainly in the stratum spinosum. These cells are believed to be responsible for the processing and presenting cutaneous antigens to lymphoid cells in the epidermis. Merkel's cells are generally present in the thick skin of palms and soles. Free nerve endings that form an expanded terminal disk are present at the base of the Merkel's cells. These cells may serve as sensory mechanoreceptors.
The dermis is composed of connective tissue that supports the epidermis and binds it to the subcutaneous tissue. Two layers with rather indistinct borders have been described in the dermis. They are the outermost papillary layer and the deeper reticular layer. The papillary layer is thin and is composed of loose connective tissue and composes the major part of the dermal papillae. This layer is in intimate contact with the epidermis through the basement membrane and its adhesion is strengthened by the interdigitation of the dermal rete pegs. The reticular layer is thicker, composed of irregular dense connective tissue, and therefore has more fibers and less cells than the papillary dermis. The dermis contains a network of elastic fibers in which the thicker fibers are found in the reticular layer. A rich capillary network in the papillary layer surrounds the epidermal ridges and functions in regulating body core temperature and nourishing the overlying epidermis. There is a rich supply of nerves in the dermis which innervate the mechanoreceptors ( Meissner and Pacinian corpuscles ) as well as supply the vasculature and hair follicles with sympathetic autonomic nerve fibers. The subcutaneous tissue consists of loose connective tissue with a predominance of fat cells.
The skin appendages include the pilosebaceous unit, the eccrine sweat glands, and the apocrine glands. The pilosebaceous unit consists of the hair follicle, one or more sebaceous glands, and the arrector pili muscle. The sebaceous glands are holocrine glands because its products of secretion are released with remnants of dead cells which together are called sebum. The function of sebum is largely unknown , however it may have some antibacterial and antifungal properties. Sweat glands are widely distributed in the skin. The eccrine sweat glands are simple, coiled tubular glands whose ducts open at the skin surface and are a responsive part of the thermoregulatory apparatus. Another type of sweat gland, the apocrine glands, is present in the axillary, areolar, and anal regions. These glands produce a viscous secretion that is initially odorless, but which acquires its distinctive odor by bacterial decomposition. Apocrine glands are innervated by adrenergic nerve fibers. The glands of Moll in the margins of the eyelid and the ceruminous glands of the external auditory canal are modified sweat glands.
Primary lesions include:
Secondary lesions include:
Also during the physical examination one should determine and describe the arrangement and configuration of the lesions (linear, reticular, annular, serpiginous, herpetiform, or grouped) as well as the location and distribution of the lesions (symmetrical, flexor, extensor, exposed skin or, nonexposed skin). A look at the patients hair and nails should also be performed.
After the history and physical examination has been complete, the lesions should be further examined using some cutaneous diagnostic procedures. A hand lens can be used to magnify the lesion and see greater detail of the skin changes. A potassium-hydroxide mount should be done when there are dry scaling lesions or missing and broken hair. To prepare, the edges of the skin lesions are scraped and placed on a slide. Then two drops of 20% KOH is placed followed by a coverslip. The slide is then gently heated and examined under a microscope. If a fungal infection is suspected, a fungal culture should be obtained. For bullous or vesicular lesions, a Tzanck smear should be done. Using a scalpel, the fresh blister is unroofed and the base is scraped. This material is smeared onto a slide and air-dried. Wright's or Giemsa stain is then applied and the slide is examined under the microscope. When there is severe pruritis which is worse at night or excoriated papules and burrows in the skin, then a scabies preparation should be done. An unexcoriated papule or burrow is scraped and then smeared onto a slide. Mineral oil is applied and a microscopic exam is done.
A Wood's light examination should be done when there is a suspicion of tinea or pigmentary disorders. The skin is cleansed of soap, cosmetics, and deodorants. The room is darkened and the lamp is held 4 - 6 inches away from the lesion. A golden yellow color suggest tinea versicolor, a bright yellow-green color suggest Microsporum, a pale green suggest Trichophyton schoenleini, and no color suggest Trichophyton tonsurans. Immunofluorescence stains should be done when there are bullous diseases, vasculitis, or connective tissue diseases. Direct immunofluorescence exam is the identification of the antibody or other proteins bound in tissue, whereas the indirect exam involves the identification of the antibody in the body fluids. A biopsy of the lesion should be taken from the active border of the lesion. This will yield the best chance for making a diagnosis.
In the biopsy specimen a variety of pathology can be seen. The definitions for some basic cutaneous pathology need to be defined. These include:
Staphylococcal scalded skin syndrome is characterized by tender skin and a red scalded appearance to the skin. The skin may slough off with light lateral pressure and cause an intraepidermal separation of the skin. This occurs mainly in infants and children. Staph. aureus elaborates an epidermolytic toxin which cleaves the epidermis longitudinally at the level of the stratum granulosum. Treatment is with oral penicillinase resistant PCN. Folliculitis is the inflammation or infection of the hair follicles. Characteristically there is pain, itching, burning, and pustules in the hair follicles. The scalp and extremities are favored sites. Treatment includes mixed ointment preparations and antistaph antibiotics.
Furunculosis and carbunculosis are characterized by tender round subcutaneous nodules that are usually fluctuant or capped with a small pustule. They typically spontaneously rupture. Carbuncles tend to be deeper and extremely painful infections. Clinically, they present as boils and are caused by Staph. aureus. Treatment includes moist heat and surgical drainage.
Erysipelas is characterized by red, tender, and edematous skin. The erythema is sharply defined with or without vesicles. Fever, chills, and malaise are common. It involves an acute infection of the skin and subcutaneous tissues as well as the lymphatics. Common sites of involvement are the face, scalp, hands, legs, and genitalia. Causative organism is group A beta hemolytic Strep. and is treated with PCN, aspirin, bed rest, and hot packs. Cellulitis is a diffuse inflammation of loose connective tissue, particularly the subcutaneous tissue. It is characterized by rapidly spreading erythema and brawny edema that is tender with poorly defined borders. The causative organism is usually beta hemolytic Strep. and the treatment involves PCN.
Scarlet fever is characterized by a bright red exanthem of tiny red dots and 1 - 2 day history of severe pharyngitis. It usually follows Strep. tonsillitis or pharyngitis and is caused by group A Strep. that produces an erythrogenic toxin. Other symptoms include fever, malaise, and a strawberry tongue, which is a tongue coated white with prominent bright red papillae particularly on the lateral margin. The exanthem begins as an erythematous blush on the neck beneath the ear, on the chest, and in the axilla quickly spreading to the abdomen, extremities, and face. Treatment includes benzathine PCN G and oral PCN.
Kawasaki's disease (Mucocutaneous Lymph Node Syndrome) is characterized by fever, conjunctival inflammation, mucous membrane changes, erythema, and edema of the hands and feet with desquamation, erythema multiforme-type reaction, and lymphadenopathy. It is more common in children and the etiology is unknown. Actinomycosis is caused by Actinomyces and Arachnia which are normal flora of the mouth and tonsillar crypts. It is an infection of endogenous origin that occurs when organisms normally found in the mouth are introduced into traumatized tissue. There are three types with the cervicofacial being the most common. It develops slowly beginning with swelling of the soft tissues and darkening of the overlying skin. The swelling continues to a "wooden" type of hardness and the surface appears uneven or lumpy. Abcesses can develop with multiple draining sinuses. The diagnosis is made with visualization of granules in the pus under microscopic examination and with anaerobic culture. The treatment is surgical drainage and PCN.
Skin tuberculosis is produced by direct inoculation or by lymphatic or hematongenous spread. The course begins as a localized inflammatory nodule ( tuberculous chancre ) which is accompanied by regional lymphadenopathy and lymphangitis. In scrofuloderma, the tuberculous lymph node extends to the skin resulting in the development of ulcers and numerous fistulas.
Warts are hyperkeratotic, skin-colored papules with velvety verrucous surfaces that are caused by the human papilloma virus. They are usually asymmetrical and the lesions assume a variety of shapes. Multiple flat warts are common on the face, neck, forearms, and knees. Filiform warts are slender, finger-like warts that are common on the face, particularly around the eyes and on the eyelids. Warts commonly occur in areas of trauma. The differential diagnosis includes actinic keratosis, seborrheic keratosis, squamous cell carcinoma, skin tags, and lichen planus. The treatment is cryotherapy. Rubeola is characterized by a cough, coryza, conjunctivitis, high fever, and a generalized morbilliform exanthem. Koplik's spots precede the rash and are irregular, blue-white pinpoint elevations of the mucosa, usually on the buccal mucosa near the second molar. It is caused by the paramyxovirus and is more likely in the winter or spring. The rash begins over the forehead and face then spreads down over the neck and trunk.
Rubella is characterized by a morbilliform eruption that initially involves the face then spreads to the neck, arms, and trunk. It then fades from the face and upper body before it reaches the feet. The rash lasts 1 - 2 days in any anatomic spot. There are also mild systemic symptoms, as well as generalized lymphadenopathy. It is caused by the rubivirus. There also may be red, pinhead sized punctate macules over the soft palate. Erythema infectiosum is characterized by circumoral pallor, red patch on the face ("slapped cheek"), and a reticulated eruption of the arms and upper trunk after 1 - 4 days. It is caused by the parvovirus and is more common in the winter and the spring. The treatment is symptomatic.
Hand, foot, and mouth disease is caused by the coxsackie virus A16. Following an incubation period of 5 - 7 days, fever and stomatitis develop. One to three mm vesicles on erythematous bases appear on the buccal mucosa, tongue, and other areas in the oral cavity. Cutaneous vesicles on the palms and soles then follow. The lesions lasts approximately 3 - 7 days. The treatment is symptomatic.
Molluscum contagiosum is caused by the pox virus. It is characterized by the formation of several papules on areas likely to have been scratched. Papules are dome-shaped, flesh-colored, and waxy with a central umbilication. The lesions erupt 2 - 7 weeks after exposure and lasts several months to years. The treatment includes cryotherapy, excision, TCA, or no therapy.
Piedra (trichosporosis) is a distinctive condition of the hair shaft characterized by firm, irregular nodules composed of the elements of the causative fungus. White nodules are caused by Piedraia hortai and black nodules are caused by Trichosporon cutaneum. The treatment is clipping of the affected hairs. Tinea corporis is most commonly caused by Trichophyton rubrum. The lesions are characterized by erythematous scaling with central clearing or large geographic papulosquamous plaques. On KOH preparation there is branching septate hyphae. The treatment is with antifungal creams. Tinea capitus, most commonly caused by Trichophyton tonsurans, is characterized by tender, oozing, weeping, pustular eruptions in the scalp that lead to bald patches and scaling skin. The treatment is with oral griseofulvin.
Candidiasis is caused by Candida albicans and is characterized by erythema of the skin with or without satellite pustules. Moisture, heat, irritation, and immunocompromised status of the patient all promote infection. Involvement of the mouth is termed perleche. The treatment includes nystatin or miconazole topically. Chronic mucocutaneous candidiasis is defined as oral candidiasis for greater than three months or chronic and persistent candida infections of the mucous membranes, skin, and nails. The treatment includes oral Ketoconazole followed by a maintenance schedule. Parasitic Infections
Pediculosis capitus is usually found in children. It is head lice found on the scalp, behind the ears, and on the posterior neck. Whitish nodules (nits) are found on the hairs of the posterior scalp. Treatment is with lindane 1% shampoo for four minutes, environmental cleaning, and a nit comb.
Latent syphilis is characterized by no systemic signs or symptoms, but there is positive serology. Tertiary syphilis occurs 2 - 20 years after the primary infection. The skin lesions are brownish-red nodular lesions in arcuate patterns. These gummas are found arising on the face, shoulders, and extremities and can ulcerate. Twenty percent develop neurosyphilis and thirty percent develop aortic dilatation with valvular incompetency and aneurysm formation. The diagnosis is made using darkfield microscopy of a fresh lesion. The RPR is used for screening and the FTA-ABS is drawn if the RPR is positive. The treatment includes Benzathine PCN 2.4 million units IM for primary, secondary, or early latent syphilis. PCN G 6 - 9 million units IM over 3 - 4 weeks for tertiary syphilis. Retesting should be done at 3, 6,and 12 month periods after treatment.
Disorders of Pigmentation Solar lentigo has its onset after puberty and usually after age 40. There is a history of chronic exposure to solar radiation with the lesions being confined to sun-exposed areas. They are also called liver spots or old age spots. They are characteristically dark brown and large (often greater than 1 cm ) with irregular borders. The epidermis is atrophic. They do not fade in the winter or darken in the summer. Histologically, there is an increased basilar pigmentation with an increased number of melanocytes. Neurofibromatosis is characterized by the presence of 6 or more café-au-lait macules that are greater than 1.5 cm in diameter and neurofibromas. The neurofibromas are soft, pedunculated, flesh-colored papules and nodules. Peutz-Jeghers syndrome is an autosomal dominant disorder with pigmented cutaneous/mucosal macules and intestinal polyposis. In childhood, the small pigmented macules arise on perioral skin, lips, oral mucosa, elbows, and fingertips. Facial pigmentation may fade with time, but the mucosal pigmentation persists. The polyps are not considered premalignant. The treatment is for signs or symptoms of bleeding or obstruction.
Melasma is the hyperpigmentation occurring on the forehead, upper lip, chin, and nose, as well as the malar regions, temples, and mandibular rami. It is seen most commonly in pregnancy. The pigmentation is mottled and macular. Adrenal insufficiency is characterized by an excess production of ACTH and MSH which causes hypotension, altered mental status, weakness, nausea and vomiting, diarrhea, and the hallmark, diffuse hyperpigmentation of skin and mucous membranes. This hyperpigmentation is accentuated in creases, sun-exposed sites, and genitalia. The treatment is glucocorticoid and mineralocorticoid replacement.
Rosacea is an inflammatory disease affecting the sebaceous follicles of adults. It is most common in women greater than 40, but is more severe in men. A ruddy complexion characterized by vascular dilatation with or without acneiform papules and pustules. It preferentially affects the central face and involvement of the nose leads to rhinophyma. These patients are prone to flushing which may occur when drinking hot coffee or tea. The treatment includes avoidance of flare factors, oral tetracycline, and surgery for rhinophyma.
Apocrine chromohidrosis is a disorder of the sweat glands of the face and axilla. There is characteristically a blue-black discoloration of the sweat that fluoresces under the Wood's light. Miliaria occurs with keratinous sweat duct obstruction. Miliaria crystallina is asymptomatic, transparent, superficial minivesicles on uninflamed skin, often in intertriginous areas. Miliaria rubra is characterized by pruritic, 1 - 3 mm in diameter, erythematous macules that are extrafollicular and may be pustular. They are common on the neck and trunk. Miliaria profunda is commonly associated with the heat stress syndrome and is characterized by white papules of 1 - 3 mm in diameter without erythema.
Pseudofolliculitis barbae occurs primarily among blacks who shave. Papules and pustules arise on the jawline, chin, and neck. Hyperpigmentation and keloid scarring may result from infection. The treatment involves discontinuing shaving or switching to an electric razor.
This reaction is mediated by IgE and occurs within minutes to seconds of exposure to some foreign material which the patient has been previously sensitized. Symptoms include laryngeal edema and/or bronchospasm, erythema, pruritis, urticaria, angioedema, vomiting, cramps, diarrhea, hypotension, cardiac arrthymias, or shock. The treatment includes the ABC's of resuscitation. Epinephrine 1:1000 is given subcutaneously (0.3 - 0.5 ml in adults and 0.01 mg/kg in a child) and can be repeated every 15 minutes as needed. Also, diphenhydramine IV, airway supplies, tourniquet, and scalpel are needed. Angioedema and urticaria are caused by the release of histamines. Physical causes include cold, dermatographism, pressure, and hereditary causes. It is characterized by wheals and pink papules sometimes with pale centers and without epidermal changes. The individual wheals disappear within 24 hours and often as quickly as within minutes. The wheals enlarge quickly and may appear annular or arcuate. With angioedema, the lesions are usually larger than in urticaria.
Reactive erythemas are characterized by pink or red wheals, papules, plaques, or nodules without alteration of the epidermis. The epidermal skin markings usually traverse the skin lesions without any disruption. Erythema multiforme is considered a hypersensitivity reaction to an inciting agent (bug or drug) with resulting circulating immune complexes. Typical initiating substances include herpes simplex, PCN, sulfa drugs, barbiturates, carcinoma, and lymphoma. The lesions tend to be annular erythematous plaques, urticarial papules, or target lesions. They have a tendency to involve the extensor forearms, legs, palms, and soles with mild or absent pruritis. A severe clinical variant is Stevens- Johnson syndrome with involvement of mucous membranes, fever, headache, and malaise. Bullae in the mucous membranes rapidly erode to leave ulcerative lesions. The treatment involves the removal of the underlying cause, symptomatic therapy with viscous lidocaine, and corticosteroids for severe cases. Erythema chronicum migrans (Lyme disease) is caused by Borrelia burgdorferi from a tick bite. The incubation period is 3 - 32 days. There are usually mild symptoms including headaches, fever, and aching. The skin lesion is a red macule that expands peripherally and clears centrally that develops at the site of the bite. Secondary lesions include blotchy erythema, annular plaques, malar rashes, or urticaria. The disease can lead to arthritis and neurologic or cardiac abnormalities. The treatment is doxycycline.
Behcet's syndrome is characterized by oral ulcers, genital ulcers, and iritis or uveitis. Tender subcutaneous nodules and pustules at the site of trauma are often present. The oral lesions are erythematous or edematous macules or papules that enlarge and ulcerate. The ulcers are 2 - 10 mm and punched out, often covered by a pseudomembrane.
Seborrheic dermatitis is a chronic or subacute eczematous dermatitis involving the regions of high sebaceous gland density. These areas are located on the scalp, ears, eyebrows, nasolabial folds, and midchest. There is usually mild pruritis and the scales may have a greasy quality, or yellow or orange hue. Common associative problems are bilateral otitis externa and diffuse dandruff with erythema of the scalp. The differential diagnosis includes tinea facei, atopic dermatitis, psoriasis, and SLE. The treatment involves using shampoo containing tar, sulfur, salicylic acid, or selenium. Topical corticosteroids usually controls the disease on the face, neck, and chest.
Lichen planus is flat topped, violaceous, pruritic papules in symmetric distribution with a fine whitish network covering the surface (Wickham's striae). Lesions are common on the flexor surfaces and involvement of the mucous membranes consists of lacy white patches. Oral lesions may be the only findings. Resolution of oral and skin lesions occurs in months to years. The differential diagnosis includes drug eruptions and discoid lupus erythematosis. Histologically, there is hyperkeratosis without parakeratosis and the rete ridges are elongated and pointed, like the teeth of a saw. The treatment is topical corticosteroids, reassurance, and antihistamines.
Pemphigus erythematosus also has intradermal cleft formation within or just below the granular layer. This is a less severe form of the disease and is usually confined to the face and scalp. The scaling and crusting are pronounced. Histopathologically, there is a defective cohesion of epidermal cells which lose their intercellular attachments, round up, and float off into the epidermal cavity. The intradermal cleft and blister formation is suprabasilar. Immunologic studies such as direst immunofluorescence staining reveals IgG deposition in the intercellular spaces of the epidermis in lesional and perilesional skin. The treatment involves local measures for patient comfort, such as bathing in antimicrobial soap, viscous lidocaine, and topical corticosteroids. Systemic corticosteroids are the mainstay of therapy and are started at doses high enough to suppress new blister formation.
Bullous pemphigoid is characteristic of cleft and blister formation at the dermal-epidermal junction which results in subepidermal blister formation. These tense large bullae occur on erythematous plaques, but can occur on normal appearing skin. There is no or only mild involvement of mucous membranes. Deposition of IgG and C3 occurs at the dermal-epidermal junction. Serum antibodies form against the basement membrane zone to an antigen in the lamina lucida. The disease usually begins with urticarial and erythematous plaques and after several days to weeks blisters form. When the blisters break they leave an erosion that heals with hyperpigmentation, but no scarring. Histopathology reveals the formation of a subepidermal blister. Immunopathology shows deposition of IgG and C3 in a linear band at the epidermal basement membrane zone of perilesional skin. Bullous pemphigoid differs from pemphigus because of the presence in the former of tense blisters, lack of erosions, negative Nikolsky's sign, infrequency of oral lesions, and general well-being of the patient. The treatment involves topical measures including the prevention of bacterial superinfections and systemic corticosteroids.
Cicatricial pemphigoid is a variant of bullous pemphigoid that is characterized by tense blisters and erosions of mucous membranes especially in the oral cavity, eyes, nose, and pharynx. There is a pronounced tendency for scarring and strictures. There is also subepidermal blister formation and deposition of IgG, IgA, and C3 at the basement membrane zone. The lesions are symptomless and the oral mucosal blisters may resists rupture. The eye lesions heal by forming adhesions that eventually lead to obliteration of the conjunctival sac and entropion. There is no good therapy available. Epidermolysis bullosa is an eruption that consists of subepidermal blisters on the trunk and extremities, mainly at the sites of major and minor trauma. The bullae eventually break, resulting in denuded areas that heal slowly, leaving hyperpigmentation and milia, but no scarring. The oral mucosa is often involved. Deposition of IgG along the basement membrane zone is similar to that found in bullous pemphigoid. The treatment is to avoid trauma, local care, topical antibiotics, and high doses of Vit. E. It does not respond to systemic corticosteroids.
Dermatitis herpetiformis (Duhring's disease) is characterized by intense pruritis and small grouped papules, vesicles, blisters, and erosions on erythematous plaques. It is usually distributed symmetrically over the extensor surfaces, neck, shoulders, frontal hairline, and scalp. Deposition of IgA in a granular fashion subepidermally along the basement membrane zone and in the tips of the dermal papillae are found. Iodides may induce flares and the disease is associated with gluten sensitive enteropathy. The treatment is with Dapsone or sulfapyridine orally and a gluten free diet. Topical and systemic corticosteroids are not effective.
Black hairy tongue is characterized by brown or black patches on the dorsal surface of the tongue usually caused by hyperplasia of the filiform papillae. It is associated with heavy tobacco use, fungi, and bacterial overgrowth from antibiotics.
Chelitis is an exfoliative condition of the lips. Angular chelitis is usually secondary to accumulation of moisture locally. Infections with Candida are common, The treatment includes correction of underlying cause, topical nystatin, miconazole, or clotrimazole.
Geographic tongue is characterized by red, denuded areas on the dorsal tongue forming polycyclic patches, each with yellow-white borders. The lesions may change configuration from day to day and a burning sensation is frequently noted. Fordyce's condition is tiny yellowish papules on the lips, buccal mucosa, or gingivae. Each lesion represents an ectopic sebaceous gland.
Epidermoid cyst have two different types: epidermal cyst and pilar cyst. The epidermal cyst can be single or multiple and are most likely on the face, neck, back, and upper chest. They are rounded dermal or subcutaneous swellings that contain epidermal debris, surrounded by an epidermal wall that resembles normal surface epithelium. They are usually asymptomatic, but may become infected or rupture. The treatment is surgical excision. Pilar cysts involve the hair follicles and occur on the face, neck, and trunk. They are lined by epithelium that more closely resembles hair follicle epithelium. The treatment is surgical excision.
Keratoacanthoma is caused by UV light, chemical carcinogens, genetics, and viruses. It is a rapidly enlarging nodule with a central keratin plug and usually occurs over sun-exposed skin. They are a benign, spontaneously regressing tumor, that does not invade deeper tissues. When they regress, they usually leave an atrophic scar. They need to be differentiated from carcinomas. The treatment is simple excision or intralesional 5-FU. Trichoepithelioma are solitary or multiple papules or nodules of the face that need to be differentiated from BCCA. The treatment is surgical excision.
Sebaceous hyperplasia is yellowish papules and small nodules in the face with frequently associated telangiectasias and a central punctum. The treatment is surgical excision to differentiate them from BCCA. Actinic keratosis are red or brown rough flat type papules that occur on sun damaged skin. They are caused by epithelial dysplasia and 20 - 25% ultimately transform into SCCA. The treatment is with curettage with electrodesication, cautery, or cryotherapy with liquid nitrogen.
Leukoplakia is an abnormal hyperplastic response of mucosal epithelium with excessive keratinization. Approximately 10% develop SCCA of that area.
Bowen's disease is intraepidermal SCCA and is caused by sunlight exposure and ingestion of inorganic arsenic. The lesion is papulosquamous and appears somewhat erythematous, rough surfaced, and sharply defined with variable scaling. The treatment is surgical excision.
Dermatomyositis is an acquired inflammatory disorder affecting striated muscle and skin. There is progressive muscle weakness, with myalgia and atrophy, that occurs first in the proximal muscle groups of the extremities. Physical muscle involvement follows and eventual cardiac and respiratory failure may occur. The cutaneous lesions may precede, accompany, or follow the development of polymyositis. An erythematous macular eruption often appears on the face, neck, and upper trunk. Edema, scaling, telangiectasias, and variable pigmentation changes are a part of the spectrum of skin findings. "Heliotrope" eyelids, edema, and a violaceous color of the periorbita and eyelids are characteristic. The diagnosis is made by biopsy, serum enzyme levels (increased SGOT, CPK, and LDH), and barium swallow. Morphea is a localized sclerosis of the skin and underlying tissues. It begins as an erythematous macule that becomes an ivory-colored, smooth, indurated plaque. The lesion can occur on the trunk, face, or extremities. The lesions lasts 4 - 5 years then resolves, leaving residual pigmentation or atrophy.
Hypothyroidism causes the skin to become cold, dry, and thickened. Protuberant lips and an enlarged tongue are characteristic. The hair is coarse and often sparse and the eyebrows will have thinning of hair. There can also be nonpitting edema of the face and hands. The treatment is thyroid hormone replacement. Hyperthyroidism has pink, erythematous plaques or nodular deposits in the pretibial areas (pretibial myxedema) which are the hallmarks of the disease. The treatment is a reduction of the thyroid hormone levels and intralesional corticosteroids for pretibial myxedema.
Porphyria cutanea tarda is characterized by blistering in sun-exposed areas and elevated porphyrin levels in the urine and stool. In addition to blistering, other manifestations include hypo- or hyperpigmentation of the face, hypertrichosis, and scarring alopecia.
Xanthelasma is characterized by yellowish plaques on the upper eyelids especially near the medial canthi. These patients may have normal or elevated plasma lipid levels. The treatment is scissor excision and treatment of any underlying hyperlipidemia.
Gardner's syndrome is an autosomal dominant disorder with benign skin tumors and premalignant colonic polyps. Multiple epidermal cysts, especially about the face, develop during childhood. Lipomas and leimyomata also occur. Colonic polyps begin to develop during adolescence, with over ˝ of the patients developing malignancy. The treatment is colectomy.
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