C

A painless left-sided scrotal mass with concurrent microscopic hematuria in a middle-aged heavy smoker fits a renal cell carcinoma that has metastasized down the left gonadal vein to the testis; RCC commonly presents with hematuria, and testicular metastasis is a recognized (though rare) first sign, whereas epididymitis is painful, seminoma seldom causes hematuria and usually elevates LDH, and lung cancer does not explain the hematuria pattern [Datta et al., 2001, PMID 11469344; Moriyama et al., 2014, PMID 24944706; Rouvinov et al., 2017, PMID 28559825].