Bumps can appear on your penis and groin for various reasons, but most are harmless. However, some may be caused by sexually transmitted illnesses (STIs) and require medical attention.

Read on to learn the 10 most common causes of lumps on your penis and which ones should prompt a trip to a medical professional.

Several types of blemishes can occur just about anywhere on your body, including your penis. Those include cysts, pimples, and ingrown hairs.

Cysts are firm or hard fluid-filled bumps that can appear on your penis. You could have a cyst if it:

  • closely matches the color and texture of the surrounding skin
  • doesn’t feel painful to touch, but may be a little sensitive
  • doesn’t change shape, but it gets bigger over time

If they’re popped, the area around a cyst can become sore or infected. Cysts otherwise don’t need be treated and can go away on their own in a few weeks.

Pimples happen when oil or dirt gets trapped in a skin pore, causing pus and bacteria to build up. They may be topped with a white or black substance. They don’t need to be treated and typically go away in a few weeks or less on their own, just like pimples on your face.

Ingrown hairs happen when a short (often recently shaved) hair curves back into its follicle as it grows out. Some common symptoms include:

  • dark spot where hair is located
  • filled with fluid or pus
  • itchiness or irritation

Ingrown hairs don’t usually need treatment and go away in a few weeks or less. But they can get infected and require antibiotics or removal of the ingrown hair with tweezers.

You can get dark skin moles almost anywhere on your body, including your penis. Also called a nevus, a mole is caused by skin cells producing too much melanin, the pigment that comprises your skin color, in a single small area rather than across your skin.

Moles are harmless and not worth worrying about. You may even get anywhere from 10 to 40 moles on your body throughout your life, mostly on your face, arms, legs, and other areas that get a lot of sun exposure. Keep an eye out for moles that grow larger, more jagged, or become rough to the touch — these may become cancerous.

Moles don’t need to be removed. Don’t try to remove them at home, as many home mole treatments can actually be harmful. See your dermatologist to have the mole safely cut out (excised) or shaved off with a small blade.

Pearly penile papules are tiny bumps on your penis that are the same color as the skin in that area. It’s not clear what causes these, but they’re harmless and may just be left over from when you developed in the womb.

They usually appear around the penis head, and even though they tend to look like little pimples, they don’t itch or produce any fluid. They also tend to look less prominent or completely disappear as you get older.

Here are the telltale signs of pearly penile papules:

  • look and feel smooth
  • look very tiny or threadlike
  • are usually 1 to 4 millimeters across
  • form in rows around the penis head

These papules are harmless and don’t need treatment, but you can talk to your doctor about options to remove them.

Fordyce spots are tiny bumps that can show up on your penis or the surrounding tissue, such as your scrotum. Unlike pearly penile papules, they tend to be a yellowish color and don’t form in regular groups or rows. They may form in clusters.

Almost everyone’s born with Fordyce spots (about 70 to 80 percent of adults are), but they get bigger and more visible when oil glands that they’re associated with grow when you go through puberty.

Fordyce spots don’t need to be treated, and they generally go away with time. But removal options, such as laser therapy, are available. Talk with your doctor to find out more.

Angiokeratomas are tiny, bright red bumps appear in small clusters when blood vessels near your skin become enlarged, or dilated. They’re rough to the touch and may get thicker over time.

It’s not clear what exactly causes them in each case, but the most common possible causes include hypertension (high blood pressure) or conditions that affect blood vessels near your penis, such as hemorrhoids or varicocele (dilated veins in your scrotum).

Angiokeratomas don’t usually go away and tend to be harmless. But they can be a symptom of a cell function condition like Fabry disease, especially if they appear along with symptoms like bleeding unusually often. See your doctor if you notice these red clumps.

Lymphoceles happen when lumps or swelling appear on your penis after you have sex or masturbate. They result from blockage in your lymph channels, which carry clear lymph fluid throughout your body to help your immune system.

These lumps usually go away shortly after they appear and don’t need to be treated. They’re a common side effect of having surgery for prostate conditions, such as prostate removal (prostatectomy). This can cause lymph channels to get blocked and may result in other symptoms, such as a urinary tract infection (UTI) and pelvic pain.

See your doctor right away if you notice any of these symptoms along with lymphoceles to avoid any further complications.

Some sexually transmitted infections (STIs) can cause lumps or bumps to appear on your penis or the surrounding skin if you have unprotected oral, anal, or genital sex with someone who’s infected.

Some of these STIs include:

  • Genital herpes: a viral infection that causes itchy, infected blisters caused by the herpes simplex virus, which is treatable with antiviral medication to reduce outbreaks
  • Syphilis: a bacterial infection that can cause rashes and painful sores, which is treatable by antibiotics or a penicillin injection for early-stage syphilis
  • Genital warts: bumpy, cauliflower-like growths caused by the human papillomavirus (HPV), treatable with topical antibiotics or surgical removal
  • Molluscum contagiosum: a viral skin infection that results in small, smooth, shiny bumps filled with a wax-like substance, treatable with surgical removal

Lichen planus is a type of rash that results from your immune system attacking your own skin cells.

Common symptoms of lichen planus include:

  • purplish, flat-topped bumps that spread only weeks or months after appearing
  • itchiness
  • fluid-filled blisters that burst and scab over
  • itching at the site of the rash
  • lacy-white lesions in the mouth, which may be painful or cause a burning sensation
  • blisters that burst and become scabby
  • thin white lines over the rash

Lichen planus isn’t always a cause for concern, although it can make your skin itchy and uncomfortable. For more serious cases, your doctor may recommend treatments, such as retinoids, corticosteroids, and antihistamines, among other things.

Peyronie’s disease happens when scar tissue, or plaque, forms on the shaft of the penis and causes a noticeable hard lump or band of tissue.

This is known as “waisting” or “bottlenecking.” It’s not certain how many people have this condition, but up to 1 in 11 people with penises may experience penis curvature related to Peyronie’s disease.

This scar tissue is usually found on the top of the penis, but can also appear on the sides or underside of the penis. Over time, the tissue tends to harden due to calcium buildup, making erections curved either upward or to one side and often painful. This can make sex difficult and may even shrink the penis.

Treatment for Peyronie’s disease may include:

  • injectable medications to reduce collagen buildup
  • iontophoresis using electrical currents to send medication to the tissue through the skin
  • penile traction devices for penis stretching
  • vacuum devices (penis pumps) to straighten the penis
  • extending, shortening, or straightening the penis through surgery
  • penile implant

Cancer of the penis, or penile cancer, is a rare type of cancer of the penis tissue and skin — only about 2,080 new cases were reported in 2018.

With penis cancer, lumps in the form of tumors develop from the growth of previously healthy cells that have become cancerous.

The most notable symptom of penile cancer is an abnormal lump of tissue on your penis. At first, it may just look like a typical bump, but may grow much larger and begin looking red, irritated, or infected. Other symptoms may include:

  • itchiness
  • burning sensation on the skin or when you pee
  • unusual discharge
  • reddening or graying of penis skin
  • penis skin thickening
  • bleeding
  • rash or irritation
  • swelling around the penis in your lymph nodes

Treatments for penile cancer depend on whether it’s only affecting penis skin or tissues (non-invasive) or has spread to surrounding tissues (invasive).

Non-invasive treatments may include removal of the foreskin (circumcision), chemotherapy to destroy cancer cells, or cryosurgery to freeze and break off tumors.

Invasive treatments may include surgical removal of cancerous penis tissue or the whole penis (penectomy) and, if necessary, surrounding tissue.

See your doctor if you notice a new lump, bump, or spot on your penis after having unprotected sex, especially after having sex with a new partner for the first time. If you don’t already have a primary care provider, you can browse doctors in your area through the Healthline FindCare tool.

Other symptoms to have checked out by your doctor include:

  • pain during an erection or ejaculation
  • burning when you pee
  • feeling like you have to pee more often
  • unusually colored or bad-smelling discharge from your penis, particularly colored or foul-smelling discharge
  • open sores that crack and bleed
  • hot flashes or chills
  • fever
  • feeling unusually tired
  • abnormal weight loss

You don’t typically need to worry about a lump on your penis.

But if you’ve had sex unprotected sex lately and started to notice unusual symptoms, or you’re experiencing other abnormal symptoms alongside a new lump on your penis, see your doctor right away for a diagnosis.