Investigations and Genital Skin Biopsy

Abstract

Investigations for patients with genital skin disease are relatively few. The use of Wood’s (UVA) lamp examination of groins and axillae is important if erythrasma is suspected. Microscopy of skin scrapings at the bedside helps confirms the diagnosis of scabies or pubic lice (pediculosis pubis). A skin swab for microscopy and culture is of value if a bacterial or yeast infection is suspected. A dry skin swab from any eroded or ulcerated area is important for nucleic acid amplification testing (polymerase chain reaction, PCR) to confirm or exclude herpes simplex virus (HSV) infection. Nucleic acid amplification testing (using a urethral swab or urine sample) has greatly increased diagnostic accuracy for HSV, Neisseria gonorrhoeae , and Chlamydia trachomatis infection. Skin scrapings for microscopy and culture are important to detect a dermatophyte infection such as tinea cruris. Serological screening for a possible underlying sexually transmissible infection (STI) is important to help reassure an anxious male patient who fears a possible underlying STI. If one STI is detected, screening for other STIs is mandatory, as “STIs travel in packs.” Serological testing for syphilis, hepatitis B, hepatitis C, and HIV is determined by individual risk. Any patient with a genital ulcer should be investigated with a skin swab taken for microscopy and culture, HSV testing of the skin swab by PCR and serological testing for syphilis, hepatitis B, hepatitis C and HIV. Skin biopsy of a genital ulcer for histological examination is often useful. Finally, skin patch testing is essential if allergic contact dermatitis is suspected.