A 34 year old man was referred to the emergency department by his general practitioner with a 3 day history of painful swelling of his left testicle and lethargy. He had first noticed the swelling five weeks earlier. He had also noticed an intermittent dull ache over that time but he had not sought medical attention. The patient had no urinary symptoms, history of fevers, vomiting, or weight loss. He had no clinically significant medical or family history, worked as a civil engineer, and was a non-smoker. Observations were within the expected range for all parameters except for pyrexia of 38.2°C. Examination showed an enlarged firm left testicle of approximately 5 × 4 × 4 cm with an irregular superior pole and a thickened tender spermatic cord. Examination of the right testicle and abdomen was normal.