| disease | Perianal Eczema |
Perianal eczema is a common non-infectious skin disease, with lesions mostly confined to the skin around the anus, occasionally spreading to the buttocks, perineum, and clitoris. Local symptoms may include rash, erythema, erosion, exudation, crusting, and desquamation. The condition has a prolonged course, often leading to thickening of the perianal skin, which may appear grayish-white or dark red, rough, and prone to rhagades, exudation, cutaneous pruritus, and recurrent episodes as its main characteristics. It can occur at any age.
bubble_chart Etiology
The causes of eczema are complex and variable, arising from the interplay of multiple factors, including external physical, chemical, and biological factors, as well as internal imbalances in the body's neuropsychiatric system, metabolic dysfunction, and organ dysfunction. Clinically, it manifests as a nonspecific allergic reaction, making it difficult to identify a single causative factor or alleviate symptoms by eliminating one specific factor. The causes of the disease are divided into primary and secondary types. The former has unknown origins, while the latter is often caused by inflammation or irritation from secretions due to conditions such as anal fistula or anal fissure. Common factors include the following:
(1) Allergic reactions
This is the primary cause of the disease, involving both internal and external factors, such as focal infections, allergenic foods, medications, or contact with certain sensitizing substances.
(2) Disease-related factors
During certain illnesses, such as endocrine disorders, malnutrition, digestive dysfunction, or intestinal parasitic infections (e.g., Chinese Taxillus Herb), patients may become more susceptible to allergenic substances, increasing the likelihood of triggering eczema.
(3) Local lesionsChronic inflammatory stimulation from conditions such as hemorrhoids, anal fistula, anal fissure, or fecal incontinence can also induce eczema.
(4) Irritating factors
Direct exposure of the anus to irritants like iodine tincture, alcohol, strong acids, or alkalis may trigger eczema.
(5) Neurological dysfunction and endocrine disorders
Excessive fatigue, mental stress, depression, or insomnia can also induce the disease.
bubble_chart Clinical Manifestations
(1) Acute Eczema
Acute eczema in any area generally follows the sequence of erythema-papule-vesicle (exudation)-erosion-crust (scale)-hyperpigmentation, accompanied by cutaneous pruritus. Clinically, it is characterized by prominent serous exudation, which can be droplet-like in severe cases. Intense cutaneous pruritus makes the condition unbearable for patients, leading to scratching marks and blood crusts. Bacterial infection may result in pustules, purulent exudation, and purulent crusting, presenting the distinctive appearance of eczema—multiple types of skin lesions coexisting. The anal skin is a sensitive area, where acute eczema causes particularly intense cutaneous pruritus. Fecal contamination further predisposes to bacterial infection, exacerbating symptoms. The condition may extend to the perineum, scrotum, and buttocks, severely affecting the patient's life and work, making the course highly unstable and prolonging treatment, often transitioning into a chronic phase.
(2) Chronic Eczema
Perianal chronic eczema is more common than acute eczema. Local manifestations include skin thickening, lichenification, prominent rhagade (fissures), a tendency for exudation, intense cutaneous pruritus, a chronic course, and a high likelihood of recurrence.
Based on the polymorphic nature of the lesions, their diffuse and symmetrical distribution, exudation, itching, indistinct boundaries, prolonged course, and recurrent episodes, a diagnosis can be made. However, differentiation should be made from the following diseases.
bubble_chart Treatment Measures
(I) Treatment of Acute Perianal Eczema
1. Local antipruritic measures are the primary approach to break the vicious cycle of cutaneous pruritus-scratching-cutaneous pruritus. An effective and rapid method is dampness-heat application (wet packing) or cold wet compress. The specific procedure is as follows: Prepare a solution of 4% boric acid and 0.1% rivanol in 2–3L of water, with the water temperature around 45°C. Pour it into a container, make a cotton pad with absorbent cotton slightly larger (1–2cm) and thicker (3–4cm) than the affected area. Soak the cotton pad in the aforementioned medicinal solution until fully saturated, then wring it out until it no longer drips. Apply it to the eczema-affected area, ensuring close contact between the medicinal pad and the affected skin. Cover the pad with a plastic membrane and secure it with a bandage tied around the buttocks. This can immediately relieve itching. Apply 3–4 times daily, retaining it for 1–1.5h each time, while maintaining the water temperature at around 45°C. The method for cold compress is the same, with the solution temperature preferably at 5–10°C. In summer, ice cubes can be added to the solution to lower the temperature.
2. After the above treatment significantly reduces cutaneous pruritus and suppresses serous exudation, a drying mixed shaking lotion can be applied externally, such as white lotion, calamine lotion, etc. If necessary, an appropriate amount of corticosteroid powder can be added to the lotion, but the concentration should not be too high.
(II) Treatment and Prevention of Recurrence of Chronic Perianal Eczema
1. Treatment
⑴ For thickened skin lesions, use a higher concentration of corticosteroid liniment for occlusive therapy. The solution composition is as follows:
Dexamethasone 0.1–0.3g
Anhydrous alcohol 2.0ml
Dimethyl sulfoxide 40.0g
Glycerin 20.0ml
95% alcohol, add up to 100.0ml
Usage: Clean the anal area with warm water and soap, dry it, and apply the above liniment 2–3 times consecutively. After drying, cover it with ordinary plaster or fujining plaster. The occlusion can last 6–10h and should be changed once daily. It is best to apply it before bedtime and remove the occlusion the next morning.
⑵ For milder skin lesions, apply various corticosteroid-containing ointments, creams, or lotions externally.
2. Prevention of Recurrence Perianal eczema is prone to recurrence after cure. Identifying and avoiding triggering factors require cooperation between the physician and the patient. Anal eczema is often directly related to the consumption of irritating foods, which should be strictly avoided or minimized.
Eliminate various potential causes of eczema and actively treat chronic infections such as chronic tonsillitis, dental caries, and sinusitis, as well as chronic anorectal conditions like hemorrhoids, anal fistulas, and anal sinusitis. Reduce intake of irritating foods such as hot peppers and alcohol. Identify and remove potential allergens from items, tools, and chemicals in contact with the skin. If symptoms like localized redness or cutaneous pruritus suggesting an allergic reaction appear during medication use, discontinue the drug immediately. Maintain cleanliness of the anal area, avoid scratching or friction, and refrain from using soapy water for soaking or applying irritating medications for fumigation, sitz baths, or external application to prevent worsening the condition. Prevent diarrhea, constipation, and other triggering factors.
The differentiation between perianal eczema and anal cutaneous pruritus: Eczema often presents with papules, erythema, exudation, and erosion, followed by secondary cutaneous pruritus, while the latter is primarily characterized by itching, without exudate, and may develop secondary exudation, bleeding, and erosion after scratching.
The differentiation between perianal eczema and contact dermatitis: The latter has a clear history of irritant contact, is easy to identify, with rashes limited to the contact area, presenting a single morphology, large blisters, and distinct boundaries. After removing the disease cause, the dermatitis subsides relatively quickly and rarely recurs.
The differentiation between perianal eczema and perianal neurodermatitis: The latter often begins with cutaneous pruritus, followed by the appearance of flat papules with lichenification, light brown in color, dry and firm, and the lesions may extend to the sacrococcygeal region, perineum, and scrotum.
