Itching in the perianal area, pruritus ani, is a frequently voiced complaint. In fact, it is a symptom that was well recognized in antiquity. In the earliest manuscript exclusively devoted to anorectal disorders, the Chester Beatty Medical Papyrus, 10 of its 41 remedies were devoted to the management of anal itching and irritation.²⁹ By far the most common anorectal symptom presenting to the dermatologist is pruritus ani.¹¹ The rich nerve supply to the perianal area is thought to be the primary reason for the sensitivity to potential irritants.²⁷⁰

Psoriasis is a common, immune-mediated, chronic inflammatory disease of the skin, characterized by rounded, circumscribed, erythematous, dry, scaling patches covered by grayish white or silvery white scales.²⁹¹ The lesions have a predilection for the scalp, nails, extensor surfaces of the limbs, elbows, knees, and the sacral region.¹¹² When the condition occurs in the anal area, it may cause severe pruritic symptoms. Perianal psoriasis is usually sharply marginated, with a characteristic butterfly distribution extending over the coccyx and sacrum (Figure 9-3). Psoriatic lesions are often present at other sites on the body. Smoking is associated with an increased risk of psoriasis and also with increased severity.^160,190,288 Psoriasis is an independent risk factor for myocardial infarction, coronary artery disease,
and atherosclerotic disease in noncardiac sites.^169,316 A recent large observational study suggests the association of psoriasis with malignancy unrelated to the treatment with immunosuppressants.⁵⁶ Histologically, characteristic features include epidermal thickening (i.e., acanthosis), regular elongation of the rete ridges with broadening of the deeper aspect, and elongation with edema of the dermal papillae (Figure 9-4). There may be increased mitotic activity in the epidermis. Cells of the stratum corneum usually have retained nuclei (i.e., parakeratosis). Focal collections of neutrophils in the subcorneum are known as Munro’s microabscesses.

Treatment may simply consist of moisturizers (emollients) and agents containing salicylic acid. Topical agents include corticosteroids, coal tar products, anthralin, retinoid (tazarotene), a vitamin D₃ derivative (calcipotriene), or a combination of these. In addition, the application of sunlight (not terribly practical for perianal disease) and the use of ultraviolet light B (UVB) have been found to be beneficial. More recently, the so-called PUVA treatment has been advocated. This consists of a combined systemic-external therapy, using a potent photoactive agent (i.e., psoralen) followed by administration of a special light system emitting long-wave UVA. Cancer chemotherapeutic drugs, such as methotrexate and cyclosporine, have also been advocated.

One may understandably be reluctant to treat psoriasis without dermatologic consultation unless the condition is localized to the perianal area and then only for a limited course.

Lichen planus is a skin condition that consists of an eruption of small, flat-topped papules with a distinct violaceous color and polypoid configuration. The cutaneous manifestations begin on the volar aspects of the wrists and forearms. The lesion is characteristically found on the flexor surfaces, mucous membranes, genitalia (25%), and occasionally in the perianal area. Wickham striae are intersecting gray lines that can be seen if mineral oil is applied to the plaques. This helps to establish the diagnosis.²⁶⁹ There have been rare reports of squamous cell carcinoma developing within lichen planus in the anal area.¹⁶⁴ This condition may be seen in patients with disease processes characterized by altered cell-mediated immune responses.²⁶⁹

Histologically, the papule shows focal thickening of the granular layer, degeneration of the basement membrane and basal cells, and a bandlike lymphocytic infiltrate in the upper dermis (Figure 9-5). Biopsy of the skin establishes the diagnosis.

Treatment often has less than satisfactory results, with corticosteroids appearing to be the most helpful for this condition. Topical preparations with occlusive dressings are quite useful, and systemic administration and intralesional injections have also been employed. In mild cases, antipruritic lotions and antihistamines are suggested. Rest is also helpful.

Lichen sclerosus et atrophicus is an unusual condition of unknown cause. It occurs much more frequently in women than in men. The genital area appears to be the most commonly involved site.

Physical examination may reveal the characteristic “inverted keyhole” distribution. In this situation, the disease extends beyond the mucocutaneous border to involve the skin of the vulva, perineum, and perianal area. In the vulva, the condition affects the labia, vestibule, and introitus (Figure 9-6). Discomfort, pruritus, dysuria, and dyspareunia are common complaints.

The characteristic histologic changes in lichen sclerosus et atrophicus are edema and homogenization of the collagen below the epidermis (Figure 9-7). The epidermis also shows variable hyperkeratosis and follicular plugging. Lichen sclerosus et atrophicus may be associated with squamous cell carcinoma of the vulva. An association between the condition and squamous cell carcinoma of the perianal region has also been noted.³⁵⁴

Because of the small risk of malignancy, all nonresponders or those with recurrent sclerosis should have a skin biopsy.³⁴⁹

Treatment is primarily directed to the relief of the pruritic complaints in the hope of lessening the risk for leukoplakia
and carcinoma. A mild topical steroid sufficient to control the symptoms is advocated. Retinoids and testosterone creams have also been described.^275,345 Secondary infection should be treated with appropriate antibiotics.

Atrophy of the skin is a reaction to the repeated and prolonged application of topical corticosteroids; it may also follow local injection of these products.¹⁷³ Telangiectasia occurs, indicating loss of dermal collagen, and the patient who initially complained of pruritus subsequently reports discomfort and burning.³⁵⁷ The friction of walking rubs the already atrophic and thinned epidermis.

Patients usually report a history of self-application of topical corticosteroids for many years. Attempting to remove the medication is frequently unsuccessful. Biopsy may reveal atrophy and hyperkeratosis. Because of the risk for development of this condition, it is important to discontinue the use of cortisone treatment as soon as possible.

Two types of dermatitis are caused by substances coming into contact with the skin:

Irritants include alkalis, acids, metal salts, dusts, gases, and hydrocarbons. Allergic contact dermatitis results from hypersensitivity of the delayed type, also known as cellmediated hypersensitivity or immunity.¹²² A person may be exposed to an allergen for many years before hypersensitivity develops. The allergens are numerous and varied, as follows:

The most common causes of contact dermatitis are as follows, in order of frequency:

The patch test is used to detect hypersensitivity to a substance that is in contact with the skin (see Pruritus Ani). A nonirritating concentration of agents suspected to be the cause of the contact dermatitis is applied. The patches
remain in place for 48 hours, less if burning or itching occurs. A positive reaction will produce severe pruritus and erythema or vesicles. It is wise to defer this test, however, until the rash has cleared to limit the likelihood of a severe exacerbation.

Therapy obviously is directed toward removing the underlying cause of the skin problem or the allergen. Iodine and adhesive tape are common dermatitis-inducing products in patients who undergo anal surgery. Soothing compresses such as Aveeno colloidal oatmeal, in addition to corticosteroids and possibly antipruritics, may be advisable.

Seborrheic dermatitis is a chronic, superficial, inflammatory disease of the skin, with a predilection for the scalp, eyebrows, nasolabial crease, ears, axillae, submammary folds, umbilicus, groin, and natal cleft. The disease is characterized by dry, moist, or greasy scales and by crusted, pink-yellow patches of diverse size and shape.¹²⁴ The condition is believed to be caused by hypersecretion of sebum and is apparently exacerbated by increased perspiration and emotional stress. A high fat intake is frequently noted.

Histologically, the picture is not dissimilar to that of psoriasis, but Munro’s abscesses are not seen. According to one school of thought, the two conditions are so similar that there is some justification for thinking their origin may be the same. However, more recent evidence favors a role for yeast organisms in the etiology of the condition, with therapy being directed accordingly. Still, application of corticosteroids is the primary therapy.

The term atopy is derived from the Greek word meaning “out of place“ or “strange.” It is defined as the tendency for allergies to manifest themselves by systemic symptoms, such as asthma, hay fever, and eczema.¹²¹ The condition is believed to be either a form of immunologic deficiency or possibly a blockade of β-adrenergic receptors in the skin.

Atopic dermatitis can occur as localized, erythematous, scaly, papular, or vesicular patches or in the form of pruritic, lichenified lesions.¹²⁴ The condition is often paroxysmal, with an emotional upset initiating some attacks. Other factors exacerbating the problem may be clothing, certain foods, and dryness of the skin. Superimposed infections such as intertrigo and dermatophytosis may produce further recurrences. The most common secondary skin infections in atopic dermatitis are caused by herpes simplex virus (HSV) and Staphylococcus aureus.³⁰³ In the absence of clinical signs of infection, most atopic dermatitis patients are also colonized with S. aureus on their skin lesions. This pathogen produces proinflammatory factors that trigger the cutaneous immune system.³⁴⁰ The severity of dermatitis correlates with the density of S. aureus colonization of skin lesions.⁴⁰⁶ Anti-S. aureus antibiotics have been shown to improve the severity of atopic dermatitis.⁵⁹ Histologically, hyperkeratosis and parakeratosis with acanthosis are noted (Figure 9-8). When lichenification is present, the acanthosis is increased, and there is papillomatosis, with long papillary bodies reaching to the stratum corneum. These changes may somewhat resemble those seen in psoriasis.

Treatment consists of avoiding emotional stress, if possible; avoiding extremes of cold and heat; limiting the use of stimulant beverages; and using oral antihistamines and topical corticosteroids. Prednisone, 30 to 40 mg orally for 4 to 6 weeks or possibly longer, is usually recommended. Alternatively, a parenteral preparation may be substituted.

Radiodermatitis is a particular problem in the anal area because current therapy for carcinoma of the rectum, anus, and prostate often involves ionizing radiation. In some individuals, unfortunately, the side effects of the cancer treatment may actually lead to worse symptoms than the original disease (see Chapters 24 and 25).

Many changes are found in the cell as the result of radiation therapy. Mitoses are temporarily arrested, chromosomal abnormalities occur, and there is at least a temporary halt in the normal cell cycle. The amount of skin change resulting from radiotherapy depends on the dose. These alterations may be manifested as erythema, edema, and ulceration, and symptoms may include burning, itching, or severe pain. After a period, telangiectasia, atrophy, and freckling may appear. The skin becomes dry, thin, smooth, and shiny (Figure 9-9). Radiation injury may result in the subsequent development of malignancy, in most cases following a rather prolonged latent period. The manifestations of this complication increase with the passage of time.

Results of treatment are often less than satisfactory. However, symptomatic improvement has been reported with a regimen consisting of oral vitamin A, 8,000 IU, given twice daily.²⁵¹ Hyperbaric oxygen treatment has also been recommended. Cleansing the area with mild soap and water, in addition to the use of an emollient, a corticosteroid preparation, or both, may be of help. Biopsy specimens should be taken from any suspected lesions.

Behçet’s syndrome is characterized by four main symptoms: recurrent aphthous ulcers in the mouth, skin lesions, eye lesions, and genital ulcerations.¹⁹⁷ Genital ulcerations may be found in persons of both sexes on the genitocrural fold, on the anus, on the perineum, or in the rectum. Scrotal scarring secondary to ulcers is rarely found in conditions other
than Behçet’s syndrome. Although the cause of the condition is unknown, there is some evidence to suggest that it is of viral origin or possibly represents an autoimmune disease. Behçet’s is one of the few forms of vasculitis in which there is a known genetic predisposition. Histologically, the lesions usually show vasculitis involving vessels of all sizes—small, medium, and large—on both the arterial and venous sides of the circulation.

The anal condition may be misdiagnosed as hemorrhoids, fissure, Crohn’s disease, condylomata, or STI.¹⁹⁷ Surgery is contraindicated, and corticosteroid treatment, systemically or topically, is the preferred treatment (see also Chapter 28).

Lupus erythematosus, like other connective tissue diseases, only rarely occurs in the anal area and still more rarely develops as an isolated finding in this location. The cutaneous manifestation is called discoid lupus erythematosus (DLE). It may begin with single or multiple lesions involving entire regions of the body, especially the head and neck, sternum, vulva, and perineum. The typical plaque is approximately 1 cm or more in diameter, with characteristic scales. Removal of the scales reveals patulous follicular orifices with dry, horny, keratinous plugs.¹²³ Occasionally, basal cell or squamous cell carcinoma may develop in long-standing DLE lesions.

In laboratory investigation, the LE cell test usually yields a negative result in DLE. Results of the direct immunofluorescence test are usually positive, however, as are antinuclear antibody test results.

Treatment consists of avoidance of strong sunlight, extremes in temperature, and localized trauma. Smoking cessation is recommended because smokers tend to have more active disease.^159,170 Corticosteroid creams and ointments are particularly beneficial, with intralesional steroid therapy often helpful. Systemic therapy with antimalarials and immunosuppressive agents also has been advised.

Dermatomyositis (polymyositis) is an inflammatory condition that produces angiopathy in the skin, subcutaneous tissue, and muscles. Women are twice as likely to be affected as men. Many clinical and serologic features of the disease vary widely among affected individuals, depending on the patient’s immunogenetic profile and a host of potential environmental triggers.^344,300 The disease usually starts on the face and eyelids as a heliotrope rash and may spread to other areas forming a “shawl sign” of diffuse, flat, erythematous lesions over the chest and shoulders and affecting the metacarpophalangeal and interphalangeal joints in a symmetric fashion (so-called Gottron’s sign). It is associated with a number of other disturbances, including Raynaud’s phenomenon, alopecia, urticaria, and erythema multiforme. Of particular interest to the surgeon is that in patients older than 40 years of age, visceral cancer is frequently associated with the condition. The spectrum of malignancies usually parallels the distribution in the general population with a few exceptions. Dermatomyositis carries an increased risk of cancer mortality compared with the general population.^63,350,417 Additional risk factors for malignancy include evidence of capillary damage on muscle biopsy,³⁹⁰ cutaneous necrosis of the trunk,³⁴ cutaneous leukocytoclastic vasculitis,¹⁹⁵ and older age (older than 65) at the diagnosis of dermatomyositis.²⁶⁷ Histologic changes are similar to those of lupus erythematosus. Treatment consists of rest, salicylates, steroids, methotrexate, and azathioprine.

Scleroderma is characterized by the appearance of areas that are immobile and give the skin the appearance of being “hidebound.”¹²³ The skin becomes smooth, yellowish, and
firm, and it shrinks so that the underlying structures are bound down. Although the condition frequently involves the face and hands, leading to an expressionless appearance on the former and a clawlike appearance of the latter, it can progress to involve most of the internal organs. Involvement of the small intestine may cause constipation, diarrhea, and abdominal distension. Although the colon is only rarely affected, it can produce the signs and symptoms of Ogilvie’s syndrome (see Chapter 20). Systemic sclerosis appears to be associated with a modest increase in the overall risk of malignant disease.¹¹⁴ The most significant association appears to be with lung cancer.^46,76 There is also an association with skin cancer, hepatoma, and hematopoietic malignancies,³¹⁴ and there is a marked increase in the risk of esophageal carcinoma and oropharyngeal carcinoma.³³⁴ Treatment consists of supportive measures, baths, a high-protein diet, corticosteroids, and a number of other medications, including immunosuppressives.

Erythema multiforme is a clinically and histologically distinctive skin disease that is precipitated by the following conditions, among others:

The mechanism for this particular reaction is unknown. The lesions present as flat, dull red maculopapules that may be rather small or may increase to 1 or 2 cm in 48 hours. The periphery may remain red, whereas the center is purpuric. The lesions look almost like targets. They commonly appear in the oral mucous membrane, but genital lesions are also frequent.

Histologically, the abnormality is confined to the upper dermis and lower epidermis. In more severe cases, there is necrosis of the whole epidermis. Bullae usually are subepidermal.

Treatment consists of symptomatic relief in mild cases, but in severe instances the use of corticosteroids has been suggested. Antibiotics are advised if secondary infection develops.

Familial benign chronic pemphigus is a hereditary disease characterized by a recurrent bullous and vesicular dermatitis of the neck, axillae, flexors, and surfaces that appose. The condition has been found localized to the perianal area and may pose confusion in differential diagnosis (Figure 9-10).⁴⁰⁴ The disease is transmitted as an autosomal dominant trait. It generally presents between the second and the fourth decade. Usually, the disease persists throughout life and is triggered by UV light, friction, sweating, and bacterial infections.

The condition is caused by a defect in keratinocyte adhesion based on the mutation of the ATP2C1 gene on chromosome 3q21-q24.⁶⁷ The histologic pattern is unique, with prominent intraepidermal vesicles and bullae (Figure 9-11).

Treatment consists of local or systemic antibiotics and the use of topical corticosteroids. Additionally, low-dose radiation treatment has been recommended. Localized areas have been treated by excision and skin grafting.

Pemphigus vulgaris is characterized by bullae appearing on apparently normal skin and mucous membranes.¹²⁷ The lesions usually begin first in the mouth and next
in the groin, scalp, face, neck, axillae, and genitals (Figure 9-12). It appears that an autoimmune mechanism is the cause. The condition occurs equally in both sexes, usually in adults in their fifth and sixth decades. Circulating intercellular antibodies directed against desmoglein, an adhesion molecule, may be demonstrated in these individuals.^18,364

The pathologic changes are acantholysis, cleft and blister formation in the intraepidermal areas just above the basal cell layer, and the formation of acantholytic cells (Figure 9-13).¹²⁷ Characteristic of the separation of keratinocytes is the presence of Tzanck’s cell lining the bulla, as well as lying free in the cavity.

Because of the pain associated with advanced cases, prolonged daily baths with permanganate solution may be advised. Silver sulfadiazine (Silvadene) cream, which is effective in the treatment of burns, is also useful in this condition. High-dose corticosteroids (160 mg of prednisone daily) remain the primary therapy. Immunosuppressive agents, such as azathioprine, cyclophosphamide, cyclosporine, and methotrexate, are part of the multimodality approach, which may include antibiotics, antimalarials, gold, and plasmapheresis. Treatment with rituximab with or without intravenous immunoglobulin appears to be an effective therapy in patients with refractory disease.^7,189,196

Cicatricial pemphigoid is characterized by the presence of transient vesicles that heal by scarring of mucous membranes. The condition most commonly occurs in the mouth and conjunctivae. Other areas of involvement include the pharynx, esophagus, genitalia, and anus. In rare cases, the lesion has been confined to the genital and anal areas.³⁹³ Direct immunofluorescence of the lesion reveals the presence of antibodies at the basement membrane. Individuals with autoantibodies directed at epiligrin (laminin 5) appear to have a high risk for adenocarcinoma.¹³⁹ The absence of acantholysis differentiates the condition from pemphigus vulgaris.

There is no effective medication for cicatricial pemphigoid. Obstructing areas in the larynx and esophagus may require tracheostomy or gastrostomy.