When a person discovers an unexpected change like a lump on their testicle, it is understandably a source of high anxiety. While any new lump or swelling in the scrotum warrants a medical examination, many are caused by common, non-life-threatening conditions. Determining the precise cause requires a proper physical examination and often, diagnostic imaging like an ultrasound performed by a healthcare provider. This information provides context on potential causes but is not a substitute for professional medical advice. Only a medical professional can offer a diagnosis and recommend the appropriate next steps.
Lumps Caused by Fluid Collection
Many scrotal lumps are simply collections of fluid or non-cancerous cysts that develop near the testicle. These fluid-filled masses are typically benign and often cause little to no pain. They are frequently discovered during self-examination or a routine check-up.
One common cause is a hydrocele, which involves the accumulation of fluid in the thin sac surrounding the testicle (the tunica vaginalis). This condition results in a generalized, painless swelling that can make the scrotum feel heavy. Hydroceles can be present from birth or develop later due to injury, infection, or inflammation.
Another frequent type of fluid mass is a spermatocele (epididymal cyst). This fluid-filled sac forms within the epididymis, the coiled tube behind the testicle that stores and transports sperm. Spermatoceles usually contain clear or cloudy fluid that may include sperm.
These cysts are usually small and painless, presenting as a smooth lump near the top or behind the testicle. Treatment is generally only necessary if the mass grows large enough to cause discomfort or if it is bothersome to the patient.
Lumps Caused by Swollen Veins
A structural cause often responsible for a lump, particularly on the left side, is a varicocele. This condition involves the abnormal enlargement of the veins within the scrotum, specifically the pampiniform venous plexus, a network of small veins that drain blood from the testicle. A varicocele is often described as feeling like a “bag of worms” due to the collection of dilated veins.
Varicoceles are significantly more common on the left side, occurring in an estimated 80–90% of cases due to a specific anatomical difference. The left testicular vein drains into the left renal vein at a perpendicular 90-degree angle, creating higher hydrostatic pressure. This arrangement, coupled with the longer course of the left vein, makes the valves in the left testicular vein more prone to failure, leading to the backflow and pooling of blood. While often harmless, varicoceles can sometimes cause a dull ache, a feeling of heaviness, or may be investigated if there are concerns about fertility.
Lumps Caused by Infection or Inflammation
Lumps that arise from infection or inflammation are generally accompanied by more acute and noticeable symptoms, distinguishing them from the typically painless fluid or vein-related masses. These conditions involve an inflammatory response, which causes swelling, redness, and tenderness.
Epididymitis is the inflammation of the epididymis, the tube behind the testicle, and is most often caused by a bacterial infection. In younger, sexually active individuals, this is frequently due to a sexually transmitted infection, while in older adults, it can be caused by bacteria from a urinary tract infection. The inflammation results in pain and swelling that can come on quickly and may be accompanied by a fever, a burning sensation during urination, or a discharge from the penis.
Orchitis is the inflammation of the testicle itself, which can occur alone but often presents alongside epididymitis in a combined condition called epididymo-orchitis. Orchitis is sometimes caused by a viral infection, such as the mumps virus, particularly in post-pubertal males. Both epididymitis and orchitis can cause a lump or hardened area due to significant swelling, requiring medical treatment, often antibiotics, to resolve the underlying infection.
Urgent Concerns and Necessary Action
While most scrotal lumps are benign, two conditions require immediate medical attention. The first is testicular cancer, which often presents as a painless, firm lump or a change in the texture of the testicle itself.
A cancerous lump typically feels distinctly harder than the surrounding tissue and may be described as a marble-like mass that does not easily move or separate from the testicle. Although it is usually painless, any new, solid, or firm lump on the testicle must be evaluated immediately, as early detection is a major factor in the high cure rate for this disease.
The second urgent concern is testicular torsion, which is a vascular emergency where the spermatic cord twists, cutting off the blood supply to the testicle. This condition causes the sudden onset of severe, excruciating pain, often accompanied by swelling, nausea, and vomiting. Testicular torsion is a time-sensitive emergency that requires surgical intervention within a few hours to save the testicle.
Due to the possibility of serious conditions like cancer or torsion, any new lump, swelling, or sudden pain in the scrotum necessitates a prompt visit to a healthcare provider. A doctor will typically use an ultrasound to determine if the mass is solid (potentially cancerous), fluid-filled (like a hydrocele), or a collection of enlarged veins (like a varicocele). This imaging is crucial for accurate diagnosis and appropriate management. Sudden, severe pain should be considered a medical emergency requiring an immediate trip to the emergency room.