When spots, lumps or rashes appear on the penis or scrotum, men may worry that they have a sexually transmitted disease, but in most cases the concerning spots are both common and harmless. The size, shape and color of the spot may help determine whether there is something to be concerned about.
Multiple tiny nodules beneath the skin of the scrotum and at the base of the shaft of the penis are normal hair follicles. These nodules are all similar to each other in appearance.
Small dome-shaped or jagged bumps around the crown of the head (or glans) of the penis are probably pearly penile papules. They appear in about 10-20% of all men, and are likely more common in uncircumcised men than in circumcised men. Pearly penile papules (the medical name is "angiofibromas") are not infectious and require no treatment.
Small red or purple spots with a thick, warty surface are probably angiokertomas. They appear on the glans shaft or scrotum. Most often, they appear on the scrotum of elderly men, though they may be solitary and they may appear in young men. These spots -- known as angiokertomas of fordyce -- are not infectious and require no treatment.
If angiokertomas involve the entire bathing suit area of a child, they may indicate anderson-fabry disease, which results from an enzyme deficiency and requires medical evaluation.
A small, pea-sized nodule on the scrotum, sometimes filled with a cheesy or chalky material, is probably a cyst. Scrotal cysts may be solitary or multiple. They are not infectious and require no treatment, though some men may choose to have them surgically removed.
Red patches with a well defined border may indicate psoriasis. These patches may be scaly or smooth and may arise from the friction caused by masturbation or sexual intercourse. Typically, psoriasis of the penis responds to treatment with a steroid cream. Psoriasis is not infectious.
Very small shiny pink bumps on the glans may be lichen planus. Sometimes the papules have fine scales and sometimes they are smooth. They often appear in a ring or in a line. They may or may not be itchy. Similar lesions may appear on other areas of the body, especially the wrists and shins. Lichen planus is not infectious or harmful, but it does respond to medical treatment. Most cases resolve on their own within a year.
Pink-brown or skin-colored bumps with a moist surface may be genital warts, which are caused by the human papilloma virus (HPV). Genital warts may have a smooth surface or a surface with a cauliflower appearance. They may appear anywhere on the male genitals, the thighs, the pubis (the area just above the base of the penile shaft) or the lower abdomen. Genital warts are the most common sexually transmitted disease. They require medical treatment because of their cancer-causing potential in women.
A single, round and painless ulcer of the penis or scrotum may indicate primary syphilis. The ulcer of primary syphilis typically self-resolves a few weeks after it appears. However, the disease persists in the bloodstream and may be passed on to a sexual partner. Syphilis is a sexually transmitted disease requiring medical attention. It may cause serious complications if left untreated.
A painless irregular, non-healing genital ulcer might be penile cancer. Penile cancer most often appears on the foreskin or glans. Squamous cell carcinoma, the most common type of penile cancer, occurs more frequently in uncircumcised men. Cancer is not infectious, but it does require medical treatment. When treated early, most penile cancers can be cured.
A cluster of small blisters that evolve into painful ulcers may be herpes simplex. The first episode is often associated with severe pain and a feverish illness, while recurrences may be milder. Herpes is the most common cause of genital ulceration. It is highly infectious and usually transmitted sexually.
Small dome-shaped bumps with a central depression on the penis, scrotum, inner thighs or pubis may be molloscum contagiosum. This is a harmless and common viral disease in children. In adults, it is most commonly spread through sexual contact. The infection is self-limited (lasting months to years) and is not harmful. Nonetheless, many men 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.
Itchy red rash with swelling of the glans may be balanitis. The term "balanitis" simply refers to inflammation of the glans. Being uncircumcised and having poor hygiene are both risk factors for this condition, but balanitis may result from other causes -- both infectious and non-infectious. It requires medical treatment.
The list above is not exhaustive. Self diagnosis of spots, lumps or rashes is not a good idea and sometimes a proper diagnosis can only be made with clinical tests. As with all genital signs and symptoms, seek medical advice and practice safe sex.
American Academy of Dermatology. "Genital Warts". Accessed March 22, 2010.
cancer.org. "What Is Penile Cancer?". Accessed March 22, 2010
psoriasis.org. "Treating psoriasis: genitals". Accessed March 22, 2010.