A 28-year-old man presented with a seven-day history of testicular pain. Physical examination revealed a mass in the lower pole of the left testis. This mass was a tumour suspect on scrotal ultrasound and MRI. Testicular tumour markers were negative. A radical orchidectomy was performed. Histologically, the diagnosis of polyarteritis nodosa (PAN) was made. Retrospectively, the diagnosis of PAN could have been made earlier. The patient was treated for superficial thrombophlebitis in the months prior to admission. This was considered to be a paraneoplastic phenomenon after radical nephrectomy for a conventional type renal cell carcinoma two years earlier. After the diagnosis of PAN was made on the orchidectomy specimen, the cutaneous lesions were finally recognized as cutaneous PAN. With this knowledge, a simple testicular biopsy could have avoided a radical orchidectomy. A short review of literature on testicular PAN is given.