๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
INFECTIONS
Sexually transmitted infections (see Chs. 78 & 82) and condylomata acuminata (see Ch. 79) are described elsewhere, but miscellaneous infections that favor the anogenital region are discussed below.
Perianal Streptococcal Disease
The typical presentation is that of a 3- or 4-year-old boy with erythema and sometimes crusting of the perianal area (see Ch.ย 74).ย Constipation is frequent because of discomfort. Similar findings may extend from the vaginal introitus onto the vulva in girls and less often around the urethral meatus in boys. The disease can be associated with guttate psoriasis and is frequently misdiagnosed as irritant dermatitis or candidiasis. Specimens for bacterial culture must be obtained. Group A ฮฒ-hemolytic streptococci are responsible. Treatment is with oral penicillin, amoxicillin, or a first-generation cephalosporin.
Recurrent Toxin-Mediated Perineal Erythema
Recurrent toxin-mediated perineal erythema is an unusual condition that presents 2โ3 days after a throat infection as a fine diffuse macular erythema of the perineal region. Marked local edema may be present and the hands may be similarly affected. Desquamation follows the erythema and the condition can be recurrent. Streptococcal or staphylococcal pharyngitis is the most common cause and the erythema is toxin-mediated. Long-term prophylactic penicillin may be beneficial in some patients.
Kawasaki Disease
Kawasaki disease may be triggered by bacterial toxins or viral antigens, but the exact cause has not been elucidated. It is a disease of children. In up to two-thirds of cases, perineal erythema may be a presenting feature (see Ch. 81); additional findings include strawberry tongue, fissured lips, fever, and lymphadenopathy, followed by desquamation of the hands and feet. Coronary artery aneurysms may be life-threatening. Treatment is with aspirin and IVIg. Perineal erythema has also been observed in multisystem inflammatory syndrome in children (MIS-C) due to SARS-CoV-2 infection.
Fournier Gangrene
Fournier gangrene is a severe necrotizing infection of the external genitalia, perineum, or perianal area that occurs in patients with an underlying predisposition such as diabetes or immunosuppression or who are receiving SGLT2 inhibitors. The infection is polymicrobial. Extensive surgical debridement with prolonged systemic antibiotics is necessary.
Erythrasma
Erythrasma is characterized by pigmented patches or thin plaques with fine scale that tend to occur in flexural areas, including the groin. Coral pink fluorescence under Woodโs lamp examination is diagnostic. Distinction from dermatophytosis is usually possible clinically, as scaling is diffuse in erythrasma and there is no tendency toward central clearing.
Dermatophytosis
Chronic, slowly advancing, scaly erythematous lesions may be seen in the groin (tinea cruris) or the medial buttocks in addition to the upper thighs. Central clearing is often present and pustules may be seen; there is usually (if not always) concomitant tinea pedis and/or unguium. The diagnosis is made by microscopy and culture of skin scrapings.
Genital Candidiasis
Key features
ยCandida spp. are normal commensals
ยCandida albicans is responsible for 80%โ90% of infections
ยUnderlying factors must be sought, e.g. diabetes, corticosteroids, systemic antibiotics
ยIn female patients usually seen during the reproductive years;
occurs in infants but is uncommon in children or after menopause unless a risk factor is present
Introduction
It is important to confirm the infection by microscopy (KOH preparation) and culture because many genital skin problems in men and women are erroneously attributed to candidiasis.
Epidemiology
Candida spp. are normal commensals of the mucosal surfaces of the gastrointestinal and female genital tracts and may be found in small numbers in moist areas of skin. There are at least 20 Candida spp. that can cause infections but evidence regarding their pathogenicity is conflicting. Resistance to imidazoles is an emerging problem.
Etiology
Candidiasis is more commonly seen in diabetics, especially when glycemic control is poor, and the immunosuppressed, as well as during treatment with systemic corticosteroids or broad-spectrum antibiotics. Candidiasis can be sexually transmitted and this is probably most important in recurrent infections. Polymorphisms in the mannosebinding lectin 2 gene (MBL2) have been implicated in some cases of severe recurrent candidiasis.
Clinical features
In men, balanitis, balanoposthitis, or rarely, widespread involvement of the perianal area, perineum, and groin is seen (see Ch. 77). Balanitis is more common in the uncircumcised man. The skin is erythematous and glazed with yellow pustules and erosions. In severe infections, edema may prevent retraction of the foreskin.
Women with candidiasis complain of pruritus and non-offensive vaginal discharge. Creamy white curds are visible on the vaginal walls, and there is vulvar erythema and sometimes fissuring. In severe cases swelling and pustules may be seen.
In both sexes, candidiasis may affect the perianal area with sheet-like erythema and fissuring. The inguinalโscrotal fold in men is a frequent site of involvement, and here, in addition to the erythema, the skin focally may appear white due to maceration of the accompanying scale. Satellite lesions, including pustules, are often seen.
In babies, candidiasis is a common cause of diaper dermatitis. There may be rapid spread of erythema and pustules that typically affect the skin creases, unlike the more common irritant dermatitis. Rarely, a nodular ulcerated variant may occur.
Differential diagnosis
Many inflammatory conditions of the genitalia are treated initially as a โyeastโ infection. The presence of pseudohyphae alone is not sufficient to make the diagnosis; the appropriate clinical signs must also be present. Subcorneal pustules and erosions are also seen in impetigo, but this is excluded by a bacterial culture. In women, other causes of a vaginal discharge, including bacterial vaginosis, Trichomonas infection and desquamative inflammatory vaginitis, need to be considered. Some cases are mistakenly diagnosed as vulvar eczema.
Treatment
Topical polyene or imidazole antifungals may suffice in localized balanitis or intertrigo (see Ch. 127). The addition of a mild topical corticosteroid may help ameliorate symptoms. For vulvovaginal candidiasis, intravaginal imidazoles and single-dose oral fluconazole 150โmg are equally effective; in severe acute infections or in complicated infections (e.g. associated diabetes, immunocompromised state), these therapies should be repeated after 3 days. For non-C. albicans infections, nystatin pessaries or boric acid suppositories are recommended. Sexual partners only need treatment if they are symptomatic. An essential intervention is rectifying underlying causes such as uncontrolled diabetes.
Recurrent Candidiasis
Recurrent candidiasis is defined as more than four episodes of candidiasis per year. Precipitating factors must be identified, including hormone replacement therapy. Advice should be given on foreskin hygiene and keeping the perineal area cool with cotton underwear. In women, premenstrual exacerbations are typical. Possible regimens include oral fluconazole 150โmg weekly for 6 months or clotrimazole 500โmg vaginal tablet weekly for 6 months.
Schistosomiasis
Granulomatous lesions of the genitalia are primarily a manifestation of Schistosoma haematobium infection. Men may present with epididymitis, dysuria, or prostatitis and women with dyspareunia, dysmenorrhea, or contact bleeding.