A 10 year old boy presented to the emergency department with a one day history of left testicular pain and swelling. He had no history of scrotal trauma, fever, nausea, abdominal pain, or urinary symptoms. Clinical examination showed a small, tender, palpable nodule at the upper pole of the left testis. Bilateral cremasteric reflexes were present and both testes showed a normal vertical lie. No appreciable changes were seen to the overlying skin of the scrotum. Urinalysis results were unremarkable. In view of persistent pain, urgent scrotal ultrasonography was performed for further evaluation (fig 1), which showed a small tender nodule between the left testis and epididymis. The sonographic features of both testes were otherwise normal. Fig 1 Greyscale longitudinal/transverse (A) and colour Doppler ultrasonography (B) of the left testicular superior pole. A shows a subcentimetre nodule with heterogenous salt and pepper echotexture (arrow) situated in between the left testis and epididymis, which was tender during scanning, in keeping with a testicular appendage. B shows no vascularity within the nodule (arrow), worrisome for torsion 1. What are the differential diagnoses? 2. What is the most likely diagnosis? 3. How would …

中文翻译：

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小儿左侧睾丸急性疼痛

一名 10 岁男孩因一天左睾丸疼痛和肿胀而被送往急诊室。他没有阴囊外伤、发烧、恶心、腹痛或泌尿系统症状的病史。临床检查显示左侧睾丸上极有一个小、触痛、可触及的结节。双侧提睾反射均存在，两个睾丸均呈正常垂直状态。阴囊上层皮肤未见明显变化。尿液分析结果无异常。鉴于持续疼痛，紧急进行阴囊超声检查进一步评估（图1），结果显示左侧睾丸和附睾之间有一个触痛的小结节。两个睾丸的超声检查特征均正常。图 1 左侧睾丸上极的灰度纵向/横向 (A) 和彩色多普勒超声检查 (B)。 A 显示了位于左侧睾丸和附睾之间的具有异质盐和胡椒回声纹理的亚厘米结节（箭头），扫描过程中该结节呈压痛，与睾丸附属物一致。 B 显示结节内无血管（箭头），令人担忧的扭转 1. 鉴别诊断有哪些？ 2. 最可能的诊断是什么？ 3. 怎样才能……