I have what feels like a rough mass around my vas deferens of my left testical. i have noticed slight discomfrt from yesterday. could it be cancerous?

Testicle mass: If you are feeling a testicle mass, you should have that evaluated with your pcp. It can be anything from a small clot, to spermatocele, to tumor.

Get evaluated.: To be reassuring, what you are describing sounds like an epididymal cyst, a very common, benign, and non-cancerous condition. Masses outside of the testicle itself are rarely malignant. However, i recommend you get an exam to make sure it is not something that may warrant a testicular ultrasound. I applaud your use of testicular self examinations. Continue them to see if you notice any changes.