Overview and diagnosis of genital dermatitis

Genital dermatitis presents with itching, dysuria, and burning and soreness induced by scratching. It occurs most often in people who are atopic. The rash is a poorly defined, nonspecific, scaly erythematous eruption. Lichenification, particularly of the perianal area and labia majora, is common in chronic cases. Lichenification in the genital area can be more pigmented than lichenification in other areas of the body.

Genital dermatitis can be exacerbated by:

• maceration (eg from wearing sanitary pads or night nappies, or body secretions such as sweat, faeces, urine)
• occlusion (eg from obesity, immobility in elderly people, or patients in wheelchairs).

In perimenopausal, postmenopausal and lactating females, estrogen deficiency may precipitate genital dermatitis.

Genital dermatitis can be due to contact allergy. Common allergens include topical medications, preservatives, perfumes and latex in condoms. Allergy to seminal fluid is also a possible cause in females.

In males, genital dermatitis affects the scrotum and inguinal folds. If dermatitis occurs on the penis, suspect contact with an allergen applied directly or transferred inadvertently from the fingers. Seborrhoeic and atopic dermatitis do not usually involve the penis.

Diagnosis of genital dermatitis is difficult. Examine the genital area to exclude alternative diagnoses.

If there are clinical signs of infection (eg redness, weeping, heat), take a swab and skin scraping (if tinea is suspected). If infection is confirmed, treat based on results of bacterial cultures and skin scrapings.

Infection in the genital area is commonly caused by Candida albicans or Staphylococcus aureus. In adult females, exclude Candida infection and other pathology with a low vaginal swab—if the patient has had antifungal therapy in the previous month, there may be a false negative result for candidal infection. In prepubertal females, it is not necessary to exclude Candida infection or perform vaginal swabs.

Also consider other diagnoses such as:

• urinary tract infection (in patients who complain of dysuria)—take a urine sample. For management advice, see Antibiotic choice for urinary tract infection in adults and Approach to managing urinary tract infection in children
• sexually transmitted infections
• threadworm (or pinworm) infection, if perianal itch is a symptom
• psoriasis of the genital area, particularly in children—psoriasis is a common cause of persistent perianal and genital rashes
• genital lichen sclerosus
• contact allergy to products used in the genital area.

If diagnosis is not clear, refer to a dermatologist.