Kubo Yusuke, Sonoda Kazuhiko, Ushijima Takahiro, Hara Toshihiko
Department of Orthopaedic Surgery, Iizuka Hospital, 3-83, Yoshiomachi, Iizuka, 820-8505, Japan.
Rheumatol Int. 2025 Apr 3;45(4):86. doi: 10.1007/s00296-025-05841-3.
Gout attacks and tophi due to hyperuricemia are common, but rarely occur in extraarticular flexor tendons. Milky white fluid containing urate crystals, referred to as urate milk, may incidentally accumulate in the joint cavity and tophus of patients with gout. We report a rare case of gouty flexor tenosynovitis in the finger, characterized by urate milk, which closely resembled pyogenic tenosynovitis. A 54-year-old man with a history of gout attacks presented unprovoked right ring finger pain with marked erythema, swelling, and limited range of motion of the palmar side of the proximal interphalangeal (PIP) joint. He experienced gout attacks without tophus in both feet once a year since the age of 30 years. At the time of the initial onset, the patient took uric acid-lowering drug just for one month for hyperuricemia, but then stopped outpatient treatment and had been using non-steroidal anti-inflammatory drugs (NSAIDs) only during attacks. No abnormalities were observed on radiographs, and magnetic resonance imaging (MRI) showed T1-low and T2-very high-intensity regions from precisely above the flexor tendon to subcutaneously at the PIP joint level. Blood examination revealed C-reactive protein level of 2.5 mg/L, white blood cell count of 8.1 × 10 /L, and uric acid level of 666 µmol/L (normal range ≦ 360 µmol/L). The operation was performed for the patient suspected of suppurative flexor tenosynovitis. A milky white fluid overflowed subcutaneously, and multiple gouty tophi were observed on the tendon sheath. The diagnosis of gouty flexor tenosynovitis was made based on the absence of bacteria on culture and uric acid crystals on optical microscopy. Histopathological examination revealed an accumulation of multinucleated giant cells around the amorphous deposits characteristic of gouty tophi. Gouty tenosynovitis with urate milk should be considered in cases presenting a history of gout attacks, hyperuricemia, and high T2 signal intensity on MRI, such as subcutaneous pus accumulation in the clinical picture of infection.
高尿酸血症引起的痛风发作和痛风石很常见，但很少发生于关节外屈肌腱。含有尿酸盐晶体的乳白色液体，称为尿酸盐乳，可能偶然积聚在痛风患者的关节腔和痛风石中。我们报告一例罕见的手指痛风性屈指肌腱腱鞘炎病例，其特征为尿酸盐乳，与化脓性腱鞘炎极为相似。一名有痛风发作史的54岁男性，无端出现右手环指疼痛，近端指间关节（PIP）掌侧有明显红斑、肿胀，活动范围受限。自30岁起，他每年双脚都会发作一次无痛风石的痛风。初次发病时，患者因高尿酸血症服用降尿酸药物仅1个月，之后停止门诊治疗，仅在发作时使用非甾体抗炎药（NSAIDs）。X线片未见异常，磁共振成像（MRI）显示在PIP关节水平，从屈肌腱正上方到皮下呈T1低信号和T2极高信号区。血液检查显示C反应蛋白水平为2.5mg/L，白细胞计数为8.1×10⁹/L，尿酸水平为666µmol/L（正常范围≤360µmol/L）。对疑似化脓性屈指肌腱腱鞘炎的患者进行了手术。皮下溢出乳白色液体，腱鞘上观察到多个痛风石。根据培养无细菌及光学显微镜下有尿酸盐晶体，诊断为痛风性屈指肌腱腱鞘炎。组织病理学检查显示在痛风石特有的无定形沉积物周围有多核巨细胞聚集。对于有痛风发作史、高尿酸血症且MRI显示T2高信号强度的病例，如临床表现为皮下积脓，应考虑伴有尿酸盐乳的痛风性腱鞘炎。
