Patients may seek a sexually transmitted disease (STD) evaluation for essentially anything they perceive as abnormal and that is located “below the belt.” Although the presence of an STD should always be considered and ruled out, many patients who seek care for a suspected STD have nonsexually transmitted genital conditions. For this reason, clinicians should have a basic understanding of the spectrum of both normal skin findings and common dermatologic conditions that arise in the genitalia so they can prescribe appropriate therapy, refer the patient to a dermatologist for additional evaluation and management when necessary, or provide reassurance.


This chapter discusses the nonsexually transmitted dermatologic conditions most commonly encountered in the STD clinic setting, as well as normal variants. The discussion of pathologic lesions that follows is organized by morphology and color of lesion. A review of definitions employed to describe skin lesions is found in Table 30–1. A section on ectoparasites concludes the chapter. For a more comprehensive review of genital dermatology, the reader is referred to the text references listed below.

Table Graphic Jump Location
Table 30–1. Terminology Used to Describe Skin Lesions. 
Edwards L. Genital Dermatology Atlas. Lippincott Williams & Wilkins, 2004.
Fisher BK, Margesson LJ. Genital Skin Disorders: Diagnosis and Treatment. Mosby, 1998.
Habif TB. Clinical Dermatology, 4th ed. Mosby, 2004.
Wolff K, Johnson RA, Summond D. Fitzpatrick’s Color Atlas & Synopsis of Clinical Dermatology, 5th ed. McGraw-Hill, 2005.


A thorough history is an essential component in the evaluation of an individual presenting with genital lesions or rash. Useful questions to ask include the following:


  • (1) How long has the lesion or rash been present? The duration of a genital lesion is important for directing evaluation. For example, a genital ulcer or atypical lesion that has been slowly growing over the course of months to years implies the need for immediate biopsy, whereas an ulcer of shorter duration (that does not appear atypical) may warrant a workup for common infectious etiologies, and perhaps empiric therapy, with biopsy reserved for situations in which the workup is negative and the lesion fails to resolve.
  • (2) Does the lesion look the same now as it did when it first appeared? If not, how is it different? Understanding the evolution of a lesion or rash may assist the clinician in narrowing the differential diagnosis. For example, a patient may have self-treated a herpes ...

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