Tumor lysis syndrome (TLS) is an oncological emergency that most frequently occurs in hematological and high-turnover solid neoplasia. Its incidence in solid, slowly proliferating neoplasia is unclear, primarily because of few published case reports. TLS may be triggered by chemotherapy or infection, or may spontaneously arise. Here, we present a review of the literature and a case of a 58-year-old male patient with prostate cancer who developed spontaneous TLS.