Wu Katherine, Bauer Erin, Myung Gihyun, Fang Meika A
Division of Rheumatology, University of California David Geffen School of Medicine, Los Angeles, USA.
Rheumatology Section, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA.
Eur J Rheumatol. 2018 Nov 16;6(2):98-101. doi: 10.5152/eurjrheum.2018.18116. Print 2019 Apr.
Alkaptonuria (AKU) is a rare autosomal recessive disorder that results from the deficient activity of homogentisate 1,2-dioxygenase and leads to increased levels of homogentisic acid (HGA) and its oxidized product benzoquinone acetic acid (BQA). Both HGA and BQA form polymerized deposits that lead to a bluish-black discoloration of the cartilage as well as degeneration, inflammation, and calcification of the tendons, ligaments, intervertebral discs, and large joints and increased bone resorption. A brittle and fragmented cartilage forms and leads to aberrant loading of the subchondral bone. These fragments then adhere to the synovial membrane and cause fibrosis or chondromatosis, leading to ochronotic arthropathy. Ochronotic tendinopathy most commonly affects the patellar or Achilles tendon and can lead to enthesopathy or spontaneous tendon ruptures. Ochronotic pigments deposited in the bone impair the bone mineralization process and lead to osteopenia or osteoporosis. Here, we report a case of a patient with several musculoskeletal manifestations of AKU and reviewed the literature to summarize the pathophysiology, clinical characteristics, and radiologic findings of the rheumatic features of AKU. Though medical treatment options are limited, early identification of AKU can facilitate prompt surgical intervention.
黑尿症（AKU）是一种罕见的常染色体隐性疾病，由尿黑酸1,2 - 双加氧酶活性不足引起，导致尿黑酸（HGA）及其氧化产物苯醌乙酸（BQA）水平升高。HGA和BQA都会形成聚合沉积物，导致软骨出现蓝黑色变色，以及肌腱、韧带、椎间盘和大关节的退化、炎症和钙化，同时骨吸收增加。形成脆弱且破碎的软骨，并导致软骨下骨的异常负荷。这些碎片随后附着在滑膜上，导致纤维化或滑膜软骨瘤病，进而引发褐黄病性关节病。褐黄病性肌腱病最常影响髌腱或跟腱，并可导致附着点病或自发性肌腱断裂。沉积在骨骼中的褐黄病色素会损害骨矿化过程，导致骨质减少或骨质疏松。在此，我们报告一例具有多种AKU肌肉骨骼表现的患者，并回顾文献以总结AKU风湿性特征的病理生理学、临床特征和影像学表现。尽管医疗选择有限，但早期识别AKU有助于及时进行手术干预。
