Seborrheic Dermatitis

Most people, at one time or another, will manifest one or several signs of this common condition. On glabrous skin it occurs as flat, superficial, red scaly patches with an indistinct, roughly annular outline. Typically the scalp, central portions of the face (eyebrows, nasolabial crease), retroauricular space, external ears (and canals), sternum, and intertriginous areas may be affected. This chronic, recurring problem is pruritic and prone to secondary bacterial or candidal infection. No age group is exempt, with the infants" "cradle cap" and "diaper rash" being one of the first encounters with the condition. The etiology is unknown, but exacerbations follow periods of stress. The "butterfly rash" of systemic lupus erythematosus should not be confused with seborrheic dermatitis. The collagen disease extends from cheek to cheek across the nose, and may be accompanied by a photosensitivity-like dermatitis on exposed areas of the body, along with telangiectatic and atrophic lesions.

Psoriasis

In contrast to seborrheic dermatitis, the individual lesions are deeper, palpable, sharply marginated, red papules or plaques, surmounted with a heavy white (micaceous) scale. Typical plaques are distributed on the scalp, elbows, knees, and gluteal cleft. Lesions may assume geometric or unnatural outlines from antecedent trauma (e.g., linear psoriasis in a scratch mark or plaques limited to the sunburned portion of extremities). This isomorphic response, or Koebner's phenomenon, is of diagnostic significance, although not specific, and emphasizes the need for preventive measures and patient education in this disease. The fingernails and toe-nails may be involved with minor or gross deformities, and a rheumatoid arthritis-like picture occurs in genetically predisposed patients. The most feared complication of psoriasis (and the other papulosquamous diseases) is uncontrolled spread of the condition with total body involvement. The disability is akin to a life-threatening thermal injury.

Dermatophytoses (Ringworm, Tinea Corporis)

Fungus infections are typically red, round scaly lesions of the nonhairy skin, which have an active spreading border (sometimes vesicular) and clearing of the central, older portions of the lesions. The more serpiginous bordered, the more the superficial resemblance to the tracks produced by larval form of the true worm (tinea) known as "creeping eruption." The fungal hyphae live within the outer dead, horny layers of the skin and may be demonstrated by direct microscopic examination following potassium hydroxide digestion of scrapings (Chapter 103). The lesions are usually symptomatic, in contrast to those of erythema chronicum migrans (see below), which have a somewhat similar clinical appearance.

Mycosis Fungoides (Cutaneous T-Cell Lymphoma)

A variety of clinical forms occur as the neoplastic T cells establish themselves within the skin and systemic organs. Earliest lesions are macular, erythematous, indistinct scaly superficial areas that ultimately show admixed hues of red and yellowish discolorations (poikiloderma). Larger dermal infiltrations of the abnormal cells produce well-circumscribed, deep, red plaques that resemble psoriasis, except that they lack the heavy scale and characteristic distribution of the benign condition. Instead of the more regularly annular lesions of psoriasis, mycosis fungoides plaques tend toward figurate, scalloped, extravagant outlines. Ultimately the lesions may ulcerate or produce nodular tumors. Total body exfoliative erythroderma is frequently seen in severe cases (Sézary syndrome).

Atopic Eczema (Atopic Dermatitis)

The appearance of the disorder varies with the age of the patient and the acuteness or chronicity of the condition. Initially the lesions are very red, poorly defined, macular areas of skin that quickly become scratched, eroded, weeping, and crusted. In infants the cheeks and extensor extremities are involved; in older children the sites of predilection include the neck and antecubital and popliteal spaces. The acute lesions are very prone to secondary bacterial infection and predispose the patients to dissemination of herpes simplex, herpes zoster, and vaccinia. The severe pruritus accompanying the condition causes much rubbing and scratching, leading to marked dryness, scaling, cracking, and lichenification of the skin.

Pityriasis Rosea

The very distinctive lesions of this condition are oval, pink, superficial maculopapules with a fine peripheral scale. They are of millimeter to centimeter size and characteristically line up on the torso with the long axes of their ovals parallel to each other and the body creases. A single, annular, larger, but otherwise similar lesion, called the "herald patch," precedes the general breakout over the torso by several days to several weeks. The lesions tend to be asymptomatic. Although proof is lacking, the etiology is presumed to be viral, since pityriasis rosea is seen primarily in young adults, in limited endemic areas, in the spring and fall. A vague prodrome of malaise and low-grade fever, and mild lymphadenopathy, may accompany the rash. It is difficult to distinguish from secondary syphilis except by serological testing.

Secondary Syphilis

Weeks to months following the mucocutaneous primary chancre of syphilis, which may not be apparent to the patient, annular, infiltrative maculopapular lesions develop on the trunk, face, and extremities. They are usually associated with nonspecific constitutional complaints and adenopathy. The palms and soles are involved, and there may be accompanying patchy hair loss and tumid lesions in the anogenital area (condyloma latum) and mucous patches (flat, grayish, rounded erosions) on the oral and genital mucosal surfaces. Care must be taken when examining patients suspected of syphilis, since the lesions, particularly the anogenital oozing type, contain viable spirochetes. Serum obtained by scraping a skin lesion may be used for darkfield demonstration of the spirochete; or serological tests, which are always reactive in this stage of the disease, will confirm the diagnosis.

Lichen Planus

This uncommon disorder, of unknown etiology, like pityriasis rosea is sometimes confused with secondary syphilis. The characteristic lesions are infiltrative papules with a distinctive polygonal outline. The lichen planus papules have a flat top, violaceous color, and lacy superficial scale. They are usually present on the acral extremities, but may also be seen on the genitalia and in patches or erosions on the oral mucosa. The cutaneous lesions demonstrate the isomorphic or Koebner's response to trauma. The scalp may-show hair loss, with permanent scarring, and the nails may be thinned, pitted, and dystrophic. Biopsy confirms the diagnosis of this pruritic, chronic, but usually self-limited disease.

Tinea Versicolor

Pityriasis versicolor, the European and more appropriate name for this common condition, is manifest as a finely scaled macular eruption of diverse colors. Early lesions are small, annular, and perifollicular, usually pink to tan in color. They rapidly coalesce and may cover large areas of the upper torso, neck, and upper extremities. Ultimately, particularly on dark skin, the lesions show as hypopigmented macules. This condition results from an overgrowth of a yeast organism generally found in small numbers within the hair follicles of many people. Heat, humidity, and unknown factors contribute to the production of these asymptomatic lesions. Diagnosis is confirmed by direct microscopic examination of potassium hydroxide digested scrapings of the scales that show budding yeast organisms ("meatballs") and pseudohyphae ("spaghetti"). The hypopigmentation stems from a direct cytotoxic effect of a specific metabolite of the organism (azelaic acid) on the pigment cells. As a result, the return to a normal skin color may be delayed until long after the infection has actually been eradicated and should not be a reason for continued therapy.

Contact Dermatitis

The most common acute inflammations of the skin result from contact with environmental allergic or toxic agents, either chemical or physical. These produce intensely symptomatic red areas that may be papulovesicular, blistered, and edematous, depending on the degree of damage or local response. The hallmark is the circumscribed, patterned nature of the eruption, which reflects the mode of contact with the offending agent. Chemical and physical burns, photosensitivity, and allergic reaction resemble one another and are distinctly more common on exposed parts of the body. A careful history will identify the suspect, offending material, or modality, but confirmation unfortunately requires controlled reproduction of the condition by appropriate patch testing (Chapter 103), once the acute condition is controlled.

Herpes Simplex

Whether the primary or recurrent type of common viral infection, this condition characteristically consists of grouped, superficial, umbilicated vesicles on an erythematous base. The intraepidermal location accounts for the tendency to erosion. Unroofing the vesicle also provides easy access to material that may be smeared on a glass slide and stained to reveal the diagnostic viral infected epidermal cells (see Chapter 109, Tzanck preparation). The lesions may occur on any part of the body following inoculation, but the peri-oral and genital areas are sites of predilection (fever blisters, cold sores).

Herpes Zoster

This recredescence of a prior varicella infection greatly resembles the clinical lesions of herpes simplex except that there is an obvious dermatomal distribution corresponding to the cutaneous nerves associated with the infected posterior ganglia. A prodromal pain or burning frequently precedes the appearance of the grouped vesicles. Multi-nucleated giant cells, similar to those found with herpes simplex, are seen in Tzanck preparations.

Bacterial Infection

Impetigo is a localized staphylococcal and/or streptococcal infection that presents as a superficial blister atop a red macule that quickly evolves to eroded, exudative, "honey-crusted" lesions. On healing, the annular area remains red and is surrounded by a peripheral scale, with central clearing, and may be confused with one of the papulosquamous dermatoses. The lesions are more common in young children and generally occur on the extremities or the face.

The staphylococcal scalded skin syndrome is a severe, generalized blistering and desquamation of the skin that results from a circulating bacterial toxin. This, too, is primarily a disease of infants and young children. Toxic shock syndrome, also caused by a circulatory staphylococcal toxin, more frequently occurs in adult women as an acute febrile illness with severe multisystem dysfunction and shock. A toxic erythema may be localized to the groin area or may be diffuse. It generally proceeds to desquamation of the skin, 7 to 10 days after onset of the illness.

Kawasaki's Disease (Mucocutaneous Lymph Node Syndrome)

This disorder, which occurs in children, also shows either a local or diffuse erythema associated with edematous palms and soles, which desquamate. It does not manifest the renal insufficiency, hypotension, and shock of the staphylococcal scalded skin syndrome. Kawasaki's disease is still of unknown etiology.

Pemphigus Vulgaris

This uncommon disease of adults is one of the few truly life-threatening dermatoses. It is characterized by generalized, flaccid vesicles and bullae, on either normal or reddened skin, which quickly erode and crust. The mucous membranes are severely involved and responsible for the considerable morbidity attending the untreated condition. The disease results from an autoimmune reaction directed against the epidermis that produces acantholytic cells devoid of usual attachment processes. These may be seen readily in Tzanck preparations of the blister, and the diagnosis confirmed by biopsy and immunofluorescent studies demonstrating the specific antibody reaction at the cell surfaces. The relatively superficial locale of the intraepidermal pathology accounts for the tendency of the pemphigus blister to spread and enlarge when pressed (Nikolsky's sign).

Bullous Pemphigoid

This is a rare disease of older adults, which runs a symptomatically disturbing but generally benign course. The bullae present in this condition are large and tense, and are randomly distributed on the general body, without the regular and severe mucous membrane involvement that characterizes pemphigus. The blisters are subepidermal and therefore do not enlarge or rupture easily with finger pressure. Immunofluorescent biopsy technique reveals a diagnostic pattern of antibodies localized at the epidermal basement membrane.

Scabies

Infestation with the human scabies mite must always be ruled out when a patient complains of severe nocturnal itching and manifests multiple excoriations in and about the axillae, flexor aspects of the wrists, interdigital finger spaces, nipples, waistline, and genitalia. The pathognomonic burrow, a black dotted line produced by the egg-laying female, or the linear small vesicles that contain the mite's eggs and feces, are difficult to locate against the background of multiple scratch marks and erosions. Definitive diagnosis is established by microscopic demonstration of the organism or its products (Chapter 109).

Erythema Multiforme (Reaction Patterns)

As the name of the condition implies, a wide variety of lesion forms (macules, papules, vesicles, pustules) sharing a common inflammatory characteristic, the erythema or redness, are grouped together in this category. Since erythema multiforme itself represents the central ground of a spectrum of disorders of diverse etiology, all characterized by damage to the skin's vasculature, it is useful to consider the group in its entirety. At any point in the evolution of these conditions, one, several, or all types of the lesions described may be present. Diagnosis depends on the sequence of systemic, as well as local, events, and definite recognizable patterns emerge as classic syndromes. For the most part, additional investigation will be required to pinpoint the etiologic agent, since the reaction patterns may be broadly categorized as "allergic reactions." As a common example, all the viral exanthems fit into this inclusive definition, yet each can be separated from the other by the evolution of the typical rash, the accompanying physical signs, complaints, and epidemiology.

The lesions encountered depend on the type of vessel (superficial, small versus, deep, large) and the degree of damage. The most subtle trauma yields the evanescent lesions of urticaria at one extreme, progressing through fixed macular erythemas, vesicles, bullae, petechiae, purpura, and necrotic ulcerations. The search for the etiology of any of the reactions is as wide and complicated as outlined for urticaria (Chapter 106), the least alarming of the representative lesion types. Although the broad view of possibilities should be kept in mind, each type of lesion is associated with a smaller range of probabilities, as the following representative samples indicate.

Acne Vulgaris

Occlusion of the distal hair follicle above the functioning sebaceous gland leads to distension of the follicle and produces the cardinal lesions, comedones. Those remaining just below the skin surface (closed comedones) are flesh-colored, enlarging papules, while the impacted follicles that communicate with the exterior (open comedones) are dark-appearing masses commonly called "blackheads." The color is from native melanin pigment, as well as oxidized lipid material, and is not an accumulation of external dirt. These lesions continue to expand until they break through the distended follicular epithelium, incite a brisk inflammatory response, and quickly pass through to their resolution as erythematous papules and pustules. Larger cystic dilatations incite larger abscess-like reactions, which heal slowly and frequently leave permanent scars. To some degree, acne is a universal mark of adolescence, and both external (friction, rubbing, oils) and internal factors (endogenous steroids) contribute to the evolution of the condition. The face and the upper torso are areas of predilection.

The distinctive feature of Agent Orange exposure in man is a severe form of comedonal (open) lesions known as chloracne. Either systemic or topical exposure to a variety of halogenated biphenyl organics predisposes to this condition, without regard to age of the patient.

Acne-like eruptions are associated with elevated adrenal corticoids (Cushing's disease or exogenous drugs) and from ingestion or administration of iodides and bromides. These outbreaks may be limited to acne-prone skin or become more generalized. They are usually monomorphic, inflammatory lesions (erythematous papules and pustules) without the usual comedonal component visible in acne vulgaris. Both bacterial and nonbacterial folliculitis occurs anytime hair-bearing areas are subjected to external friction, heat, humidity, etc. Occupational exposure to machine oils and tars produces localized varieties that contain all types of lesions seen in acne. A more generalized eruption, actually a Pseudomonas folliculitis is reported with "recreational" hot tub immersion. Pseudofolliculitis barbae is a common affliction in the bearded skin of black men where the irritation of shaving and the physical characteristics of the hair join to produce plugged follicles that trap and deflect the growing hairs. These appear to burrow and grow into the skin, inciting inflammatory pustules and granulomatous papules.

Rosacea

This is an acne-like condition that occurs on the face and upper torso of older patients. Susceptible individuals are usually very fair skinned. Both ultraviolet damage and easy facial "flushing" are prerequisites for the development of the lesions. The center of the face, including the nose itself, bears the brunt of the damage. Telangiectases and intensely inflammatory red papules and pustules develop, as well as fleshy granulomatous papules that progress unless the patient receives adequate therapy and counseling. The bulbous, red, misshapen nose is the ultimate consequence of continued neglect.

Granulomas

Deep dermal cellular infiltrates, the focal, chronic inflammatory granulomas usually present as raised, red to skin-colored papulonodular lesions. They are of diverse origin, and although some may have particular shapes, colors, and distributions, a biopsy is generally required to confirm the diagnosis.

Benign Tumors

Malignant Tumors

Peutz–jeghers Syndrome

Small brown to black macules, usually under 5 mm in diameter, are observed on the face and extremities during the second and third decade of life. They are asymptomatic and have a predilection for the vermillion lips, buccal and rectal mucosa, central portion of the face, and tips of the fingers and toes. This is an autosomal dominantly inherited condition associated with gastrointestinal polyps that are, for the most part, benign.

Leopard Syndrome (Lentignosis Profusa Syndrome)

This autosomal dominantly inherited condition is characterized by multiple generalized small dark freckles (lentigines) present at birth and the other parts of its mnemomic title (lentignosis, electrocardiographic conduction defects, ocular hyperteloresis, pulmonary stenosis, abnormalities of the gentilia, retardation of growth, and deafness, sensor-neural).

Generalized Neurofibromatosis (Von Recklinghausen's Disease)

Regularly outlined ("coast of California") brown macules 1 to 5 cm or more, usually more than six in number, and axillary freckling (Crowe's sign) are the characteristic local areas of hyperpigmentation that characterize this condition. They have their onset during infancy and increase in size and number. The conspicuous cutaneous neurofibromas develop after puberty. In 50% of the cases, the condition is inherited as an autosomal dominant, and there may be a wide range of associated systemic conditions. Lisch nodules are pigmented iris hamartomas that are asymptomatic but are useful in establishing the diagnosis.

A variety of osseous abnormalities, primarily scoliosis, are seen. Symptomatic tumors of the acoustic and optic nerves, and mental retardation, are frequent central nervous system problems. Acromegaly, cretinism, thyroid abnormalities, Addison's disease, and diabetes have all been reported with neurofibromatosis, and a significant number of patients with pheochromocytoma also have multiple neurofibromatoses. Hypertension and severe vascular deformities are also reported in children with the condition. Large tumors may produce grotesque malformations of the physiognomy, as exemplified by the notorious "Elephant Man."

Hypopigmentation

Hypopigmentation or depigmentation may occur locally following any inflammatory condition of the skin and is most common in tinea versicolor infections. Vitiligo probably represents a systemic autoimmune response against the patient's own pigment cells. It occurs as sharply marginated, usually annular, areas of white skin. The lesions are symmetrical and have a predilection for the face, neck, and acral parts of the extremities. Other autoimmune diseases (thyroiditis, pernicious anemia, diabetes mellitus, and alopecia areata) may be associated with the condition.

Peculiar, geometric, elliptical shaped, hypopigmented macules ("ash leaf macules") scattered on the torso are considered one of the earliest pathognomic signs of tuberous sclerosis. This autosomal, dominantly inherited syndrome is also known as epiloia (epilepsy, low intelligence, and adenoma sebaceum). The skin lesions (adenoma sebaceum) are multiple, yellow-pink papulonodules that develop in the central portion of the face during childhood and superficially resemble a persistent acne. Periungual fibromas and shagreen patches (leathery, collagenous plaques about the lumbosacral area) are also commonly seen. Retinal and cerebral tumors account for the neurologic findings associated with the condition, and there is an increased incidence of other unusual tumors (renal hamartomas and cardiac rhabdomyomas) in these patients.

Scleroderma

The hallmark of the disease is the poorly defined induration and thickening of skin, primarily in the acral extremities and the face. The patient develops a characteristic pinched appearance and is unable to smile easily. Irregular mottling and pigmentary disturbances are seen in the affected skin. Hypopigmentation, with surrounding color about the hair follicles, produces a "salt and pepper" look. Ulcerations, particularly of the fingertips, may be present, and as previously described, telangiectasia and calcinosis cutis.

Eosinophilic Fasciitis (Schulman's Syndrome)

This resembles scleroderma, manifesting a marked edema and induration of the extremities. Most patients have eosinophilia and hypergammaglolubinemia, and on deep biopsy, a histopathologic picture distinct from scleroderma.

Scleredema

An uncommon diffuse, slightly erythematous induration of skin usually on the upper torso and neck. If the face is involved, the resemblance is of the "moon face" and "buffalo hump" appearance of Cushing's disease. The condition may follow acute bacterial febrile conditions, although an association with diabetes mellitus is noted.

Erysipelas and Cellulitis

Acute bacterial infection presents as red, hot, sharply marginated, indurated, tender plaques, most commonly seen on the face and extremities. Streptococcal infection is a frequent cause, although hemophilus infection may be seen in children. Infections by unusual organisms (e.g., cryptococcus) may occur in immunosuppressed patients. Repeated Streptococcal infections of the extremities, with resultant hypertrophy, ultimately lead to elephantiasis, a grotesque enlargement of the affected part with fibrous overgrowth of the skin and the development of deep nodular tumors with intervening crypts and tunnels.

Necrobiosis Lipoidica Diabeticorum (NLD)

A "doorway diagnosis" of the typical lesion can be made, so characteristic is its appearance. A well-circumscribed, annular to oval, atrophic plaque on the anterior shins, usually several centimeters in diameter, NLD has a typical yellowish color with a mottled erythema contributed by the superficial, dilated blood vessels. A biopsy is diagnostic. Although less than 0.5% diabetics have NLD, more than 50% of patients with NLD have diabetes. Long-standing lesions frequently ulcerate.

Lichen Sclerosus et Atrophicus

The typical lesions are bone white, very smooth, atrophic, sharply marginated, oval to annular plaques that typically appear on the genitalia, although they may appear anywhere on the body. Diagnosis is confirmed by biopsy. The chronic lesions may ulcerate and develop areas of squamous cell carcinoma.

Chronic Arterial Ulcers

The ulcerations that accompany arteriosclerotic and hypertensive cardiovascular disease are painful, sharply marginated, and found on the lateral lower extremities and toes.

Stasis Ulcers

The lesions associated with venous insufficiency are more commonly present over the medial malleolus, usually with pitting edema, varicosities, mottled pigmentation, erythema, and nonpalpable petechiae and purpura. The stasis dermatitis and ulcers are generally pruritic rather than painful.

Vasculitic Ulcers

These also occur on the lower extremities and are painful, sharply marginated lesions, which may have associated palpable purpuras and hemorrhagic bullae. The collagen diseases, septicemias, and a variety of hematological disorders (e.g., thrombocytopenia, dysproteinemia) may be the cause of this severe, acute condition.

Pyoderma Gangrenosum

This occurs as single or multiple, very tender ulcers of the lower legs. A deep red to purple, undermined border surrounds the purulent central defect. Biopsy fails to reveal a vasculitis. In half the patients it is associated with a systemic disease such as ulcerative colitis, regional ileitis, or leukemia.

Infectious Ulcers

These ulcers follow direct innoculation with a variety of organisms and may be associated with significant regional adenopathy. Mycobacteria infection, anthrax, diphtheria, blastomyosis, sporotrichosis, tularemia, and cat-scratch fever are examples. The genital ulcers of primary syphilis are typically nontender with a clean, firm base. Those of chancroid and granuloma inguinale tend to be ragged, dirty, and more extravagant lesions.