Differential diagnosis of molluscum contagiosum and tinea cruris, and etiology and treatment of scrotal pruritus.

This disease is a benign skin condition caused by the wart virus, with an incubation period of 2-7 weeks. It initially presents as rice-grain-sized, hemispherical papules, gradually increasing to the size of a pea, with a slightly concave center, resembling an umbilicus, and a waxy sheen. Early on, the papules are firm, but later soften, turning grayish-white or pearly. If the tip is punctured, a cheesy substance can be squeezed out; this is called a molluscum body.

The number of lesions varies, and they may be scattered or clustered, but they do not merge together. The rash usually resolves spontaneously within 6 to 9 months, but it can persist for 3 to 4 years or more. The course of the disease is not related to the number of lesions, and no scars are left after healing.

Use small tweezers to squeeze out the molluscum bodies, then apply 2% iodine tincture, trichloroacetic acid, or phenol, and apply pressure to stop the bleeding. For keratotic molluscum contagiosum, liquid nitrogen cryotherapy, laser, microwave therapy, or electrolysis can be used, or surgical excision may be performed. Secondary bacterial infections should be treated with antibiotics. For those infected through sexual contact, testing for other sexually transmitted diseases should be conducted, and their sexual partners should also be thoroughly examined and treated if infected.

Because the skin in the groin area has many folds and sweats a lot, it provides a good environment for dermatophytes to multiply. Tinea cruris commonly occurs on the skin of the thigh opposite the scrotum, and can occur on one or both sides, with lesions appearing as annular or semi-annular patches.

It initially appears as small patches of erythema on the inner upper thigh, covered with scales, gradually spreading outwards with clear, slightly raised borders. Papules, vesicles, pustules, and crusts may develop on the affected area. The central area may heal spontaneously and flatten, leaving pigmentation or desquamation. Severe itching is common. In severe cases, the lesions often extend to the inner thigh, perineum, or perianal area, and may also affect the scrotum or the base of the penis. Prolonged scratching can lead to local skin infiltration, thickening, and lichenification, accompanied by pigmentation.

Prevention hinges on treating any existing hand or foot tinea. If both partners are affected, they should be treated simultaneously. Avoid using bath tubs and towels used by the infected person, especially in childcare facilities and group settings. Minimize the use of medications that may weaken the body's immune system, such as corticosteroids, immunosuppressants, and broad-spectrum antibiotics. Diabetes should be treated promptly if present.

Due to the anatomical and physiological characteristics of tinea cruris, the skin is delicate and should not be treated with overly irritating medications to avoid further skin irritation. Imidazole creams, such as miconazole, clotrimazole, and econazole, are generally suitable. Compound zinc oxide ointment can also be used. Additionally, 1% bifonazole cream is also effective for tinea cruris. Oral antifungal medications are generally not recommended. During treatment, underwear should be frequently washed with hot water, and the affected area should be kept clean and dry.

Seborrheic dermatitis: Sometimes it can also affect the groin area. The rash is a pale red patch with desquamation, sometimes annular, with clear borders, but direct microscopic examination for fungi is negative. Erythritis: A skin disease caused by a type of Corynebacterium, commonly found in the armpits, groin, etc. The affected skin is brick red, without an inflammatory ring at the edge, and is not itchy. Direct microscopic examination for fungi is negative. Psoriasis: Commonly known as cowhide癣 (a type of skin disease), it can affect the groin area, manifesting as annular or plaque-like erythematous patches, generally with thick scales on the surface. Similar rashes can also appear on other parts of the body. Vitamin B₂ deficiency: A syndrome of skin, scrotum, and oral cavity caused by a deficiency of vitamin B₂ (riboflavin). The main manifestation is scrotal inflammation, initially presenting as diffuse pale red patches on the scrotum with clear borders, slightly raised edges, covered with grayish-white scales or brownish-black thick crusts. Fungal examination of the scales is negative. It is often accompanied by glossitis and angular cheilitis, and tends to occur in clusters within the same food service unit.

Scrotal itching is a common symptom of scrotal eczema. The scrotal skin becomes diffusely red and swollen, with intense itching. Numerous papules and vesicles, ranging in size from pinhead to rice grain, may appear simultaneously. After scratching or rubbing, the erythema, papules, and vesicles rupture, revealing large areas of moist, eroded skin with copious pale yellow serous exudate, some of which congeals into pale yellow crusts. It is more common in manual laborers, especially in summer when the genital area is warm, sweaty, damp, and poorly ventilated. The scrotal skin is affected by sweat, friction from underwear, etc., leading to itching. Wearing overly tight jeans or non-absorbent, non-breathable nylon underwear can also cause this condition.

Fungal infections of the scrotum, such as candidal scrotal dermatitis and tinea cruris affecting the scrotum, can all cause scrotal itching.

Chronic vulvar dystrophy, allergies to certain medications, or chemical irritation can also cause scrotal itching.

Vulvar and scrotal itching can be seen in conditions such as diabetes, certain vitamin deficiencies, anemia, and leukemia.

Neurodermatitis, eczema, lice, and scabies in the scrotum can also cause scrotal itching.

Scrotal pruritus is a common localized pruritus in men. Initially, it is characterized by scrotal itching, which is usually intermittent, lasting from a few minutes to 2-3 hours each time. It is more likely to occur during leisure time or at night, and is less noticeable during periods of work stress. At this stage, the scrotum appears normal, with the exception of possible scratch marks, but no primary skin lesions such as erythema, papules, or vesicles. Because patients often scratch and rub to relieve the itching, it becomes a habit. Over time, the scrotal skin gradually thickens due to the stimulation of scratching, making the itching more intense and lasting longer. Even vigorous scratching is not enough to relieve the itching. The thickened scrotal skin worsens, and after several years or decades, the scrotum becomes swollen, as thick as tree bark, and has pigmentation. In severe cases, it can affect the penis, perineum, inner thighs, etc., and often leads to secondary folliculitis, boils, or eczema. Long-term illness can cause insomnia and depression, affecting normal life and work.

Oral medication: For severe itching causing irritability and insomnia, sedative and antipruritic medications can be taken. Usually, one or two antihistamines are chosen, such as cyproheptadine, chlorpheniramine, hydroxyzine, diphenhydramine, or promethazine. External treatment: For severe symptoms with acute inflammation, boric acid wet compresses can be applied, along with topical application of 40% zinc oxide ointment. Sitz baths with a 1:5000 potassium permanganate solution can also be used. For chronic itching, hydrocortisone ointment or 2% diphenhydramine cream can be applied. For thickened skin, fluocinolone acetonide ointment or dexamethasone ointment can be used topically, but long-term use is not recommended; it should not exceed three months.

Lichen sclerosus of the male genitalia is a relatively rare chronic inflammatory skin disease of unknown etiology. It commonly occurs on the foreskin and glans penis in men, and can easily invade the urethra, causing stenosis. The disease has a long course, is prone to recurrence, and has a tendency to become malignant. In recent years, the incidence of this disease has been increasing year by year.

It belongs to a type of lichen sclerosus, which is a lymphocyte-mediated acquired, chronic inflammatory skin disease. It mainly consists of three parts: first, non-chronic inflammation of the glans penis; second, the abnormally dry appearance of the lesion site; and third, the manifestation of arterial endarteritis under the skin of the glans penis.

Most patients have a history of phimosis. The lesions mainly occur on the foreskin, glans, urethral meatus, and anterior urethra. The glans is difficult to retract due to adhesions, and invasion of the urethra causes difficulty in urination. In addition, some literature reports that a small number of patients eventually develop squamous cell carcinoma.

The main causes of this disease are currently believed to include autoimmune infections (Borrelia burgdorferi, human herpesvirus, human papillomavirus, etc.), genetics, phimosis, and chronic urinary irritation. Phimosis is considered an important influencing factor in the occurrence and development of this disease.