Testicular bumps can have multiple causes, some benign and others serious, therefore I recommend that you see your doctor
or a healthcare professional for evaluation, testing and treatment of your symptoms if necessary. The testicle itself has multiple components which can give it an abnormal contour. For example, the epididymis adheres to the posterior aspect of the testicle providing a slightly different contour. When this gets inflamed, a condition called epididymitis, it can lead to pain and swelling of that area. Other benign causes of lumps in the testicular are include varicoceles, which are patchy growths of veins that can be palpated a a soft mass within the scrotum. Another cause, though rare, is called a hydrocele, which is a variant of congenital development when there is absence of obliteration of a sac of fluid that is retained in the scrotum and can feel like a mass. Additionally, benign testicular cysts can also lead to a palpable mass of the testicle. Finally, as you suggest, testicular cancer is the most concerning cause for a testicular mass. Although there are multiple benign explanations for testicular lumps, it is important that you see your doctor for formal evaluation and testing to rule out a more serious cause such as malignancy.