A 24-yeаr-оld mаle presents tо the clinic with аcute оnset left-sided scrotal pain and swelling that began 8 hours ago. He reports progressive worsening pain and difficulty walking due to discomfort. He denies trauma. He is sexually active with one current partner and three partners in the last year. He reports mild nausea but no vomiting. On examination, the left hemiscrotum is erythematous, edematous, and tender to palpation. The affected testicle appears slightly elevated compared to the right. The cremasteric reflex is difficult to elicit due to guarding. Prehn sign is inconclusive due to severe tenderness. Which of the following conditions must be included in the original list of differential diagnoses for this patient’s presentation?