The main question here is whether the cyst is cancerous or not.If it is not cancerous there is nothing to be done by the urologist than regular follow up.Whether the lesion is cancerous or not depends up on the CT features.In kidney
masses the imaging is the deciding factor to go ahead with the surgery or not.As I mentioned earlier renal biopsy has little role in diagnosis of kidney cancer.
What urologist would look is whether mass looks to be cancerous or benign on CT.It is better to err on the side of cancer in suspicious cases.So if in doubt go for excision of the tumor.Only 20 % of tumors which are less than 3 cm are cancerous.Rest are benign or very indolent which can be observed.
Again mid pole tumors are difficult to remove alone as it is closer to the blood vessels supplying the kidney and also the PC system(where the urine is formed). So injury to these structures precludes a partial removal of tumor alone.But still it can be done.
The questions arise if the lesion is cancerous.Then a number of questions come like what is the stage of the cancer and has it spread to the lymph nodes or not.Whether there is spread to other parts of the body.
If the mass is operable,then can a partial nephrectomy can be done or not.What are the chances of the cancer coming back if it is removed by partial nephrectomy.Whether the surgery would be done laparoscopically or by open method.What are the chances of complications.
In summary it would be better if these questions never arise in your scenario.
All the best.
If you have any specific question to ask which you think I missed , please don't hesitate to point it out.