What Is This Rash on My Penis?

Non-Infectious and Infectious Causes of Penile Skin Conditions

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If you notice a rash or spot on your penis, you may worry that you have a sexually transmitted infection (STI) or cancer. The truth is that there are a number of different reasons why you may have a rash or lesion on your penis—some worrisome and some not. 

While it's critical you see your doctor for a proper diagnosis, having some knowledge about the potential causes of this skin change can prepare you well for your visit.

Non-Infectious Causes of Penile Skin Rashes or Lesions

Sometimes what you think is a sign of a sexually transmitted infection, or even cancer, is really just your normal anatomy. For instance, you may have noticed multiple tiny bumps beneath the skin of the scrotum and at the base of the shaft of the penis—these are likely normal hair follicles.

In addition, small dome-shaped or jagged bumps around the crown of the head (or glans) of the penis are probably pearly penile papules. They are more common in uncircumcised men. Pearly penile papules (the medical term being angiofibroma) are not infectious and require no treatment.

Likewise, small red or blue spots may be angiokeratomas. They are rare and may appear only on the glans, or they may also appear on the scrotum, groin, thighs, and abdomen. They are not infectious and require no treatment unless they cause bleeding, pain, or itching.

That being said, if you notice angiokeratomas around the bathing suit area of a child, they may indicate Anderson-Fabry disease, which results from an enzyme deficiency and requires medical evaluation.

Psoriasis is a non-infectious skin condition that may occur on the penis, causing a red or salmon-colored patch with a white or silvery scale on top of it. The good news is that typically psoriasis of the penis responds to treatment with a steroid cream, although it may come back once the steroid is stopped.

Lichen sclerosis occurs in approximately one in 300 men. It causes a hypopigmented (loss of color) lesion with a crinkled skin texture. This skin condition mostly affects the glans penis and the frenulum. It can lead to painful erections and be itchy or painful. Sometimes men have trouble urinating. Lichen sclerosis is linked to skin cancer (specifically squamous cell carcinoma), so often a tissue sample needs to be taken to confirm its diagnosis. This condition can usually be treated with on-the-skin (topical) corticosteroids.

Lichen planus is another skin condition (albeit rare) that may cause raised, violet-colored, flat, polygonal bumps on the glans of the penis. Sometimes the bumps have fine white streaks and sometimes they are smooth. They often appear in a ring or in a line, and they may or may not be itchy or even sore. Similar lesions may appear on other areas of the body, especially the wrists and shins. Lichen planus is not infectious, but treatment response can be variable—it usually entails daily topical corticosteroid therapy.

Infectious Causes of Penile Skin Rashes

In addition to non-infectious reasons for a rash on the penis, there are also infectious causes of skin rash.

 

HPV and Genital Warts

According to the Centers for Disease Control and Prevention, human papillomavirus (HPV) is the most common sexually transmitted infection and can be spread through anal sex, vaginal sex, oral sex, or through skin-to-skin contact during sexual activity.

The good news is that HPV is generally cleared by a person's immune system over time. That being said, the virus sometimes does not go away for a long time, and can cause genital warts or cancer (penile cancer or anal cancer in men). HPV in the back of the throat may cause throat cancer. It's important to note though that there are many different strains of HPV, and the strains that cause genital warts are not the same strains that cause cancer.

 

Genital warts may appear as a single bump or collection of bumps around the penis or anus. The may have a smooth surface or a surface with a cauliflower-like appearance. Genital warts are variable in how they act—some go away, some get bigger, and some stay the same.

Treatment may involve a medication you take at home to apply to the wart, or your dermatologist may perform a procedure in her office to remove one or more warts. Overall, your treatment plan depends on your health, the number of warts you have, and the precise location of the warts. 

Primary Syphilis

Syphilis is a sexually transmitted infection that can be contracted during anal, vaginal, or oral sex after direct contact with a syphilitic sore—typically a firm, circular bump that does not cause pain. The sore (or sores, as a person can have multiple) may occur on the penis, around the anus, in the rectum, or in or around the mouth.

The sore of syphilis is the primary stage of syphilis, and if not treated, a person can progress to secondary and tertiary stages of syphilis—this last stage may cause very serious health problems that affect the heart, brain, liver, bones, and other organs. 

Syphilis may be diagnosed with a blood test, and can be cured with an antibiotic, as the cause of syphilis is the bacterium Treponema pallidum.

Genital Herpes

Genital herpes is a sexually transmitted infection caused by the herpes simplex virus, or HSV. It causes a cluster of small blisters that break open, evolving into painful sores that eventually scab over and heal within two to six weeks. The first episode of genital herpes is often associated with severe pain and a feverish, flu-like illness, while recurrences may be milder. That being said, it's important to note that some people infected with HSV do not develop sores. 

There is no cure for genital herpes, but medications may be taken to shorten the duration of the sores and lessen the pain they cause. If you have herpes sores, it's important to avoid sex, as HSV can be easily passed to your partner. In fact, it's advised that you wait a few days after the sores clear before having sex.

Molluscum Contagiosum

Molluscum is a common viral disease that is easily spread, and in teenagers and adults, is often contracted through sexual contact. Besides direct skin-to-skin contact, molluscum can also be spread by sharing something like a towel or mat with someone who is infected with it. People with weakened immune systems, like those with AIDs, are especially prone to getting molluscum (but anyone can still get it).

This all being said, it's important to note that molluscum is quite common in children, and is the vast majority are spread through casual contact (for example, sharing gym mats). 

This rash may cause firm, small dome-shaped bumps with a central depression and can form in adults on the face, neck, armpits, arms, hand, abdomen, and genitals, including the penis, scrotum, and inner thighs. The bumps are painless, but may itch, and turn from a fleshy skin color to a red color, as the body attacks it. 

The good news is that the infection is not harmful and is self-limited, meaning it will eventually go away on its own, except in people with weakened immune systems. That being said, many people elect medical treatment to reduce the risk of transmission, to decrease the likelihood of spreading the rash on their own skin, and for cosmetic reasons. Medical treatment may include either removal of the bumps or a topical medication applied to the bumps.

Cancerous Cause of Rash on the Penis

Penile cancer is a much less common cause of a rash or lesion on the penis. Lesions suggestive of penile cancer are often bright red, raised, and have a velvety feel. They may be itchy and painful, but not always. According to an article in American Family Physician, 5 percent to 30 percent of people with these initial lesions (called penile carcinoma in situ), progress to having squamous cell carcinoma. Penile carcinoma in situ is most common in men who are over the age of 60 and who are not circumcised. HPV is the predominant cause of this cancer.

Remember, cancer is not infectious, but it does require prompt medical treatment. The good news is that when treated early, most penile cancers can be cured.

A Word From Verywell

The list above is not exhaustive. Self-diagnosis of genital spots, lumps or rashes is not a good idea, as often a proper diagnosis can only be made with a biopsy.

As with all genital signs and symptoms, seek medical advice, practice safe sex, and continue to be proactive in and knowledgeable about your sexual health. 

Sources:

American Academy of Dermatology. Genital herpes.

American Academy of Dermatology. Molluscum contagiousum

Centers for Disease Control and Prevention. (January 2017). Human Papillomavirus: HPV and Men - Fact Sheet.

Centers for Disease Control and Prevention. (February 2017). Syphilis: Syphilis & MSM (Men Who Have Sex With Men) - CDC Fact Sheet.

Teichman JM, Thompson IM, Elston DM. Noninfectious penile lesions. Am Fam Physician. 2010 Jan 15-81(2):167-74.

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