Matthai Smita Mary, Jacob Shibu, Bindra Mandeep S, David Vinoi George, Varughese Santosh
Central Electron Microscopy Facility, Wellcome Trust Research Laboratory, Vellore, Tamil Nadu, India.
Department of Nephrology, Christian Medical College, Vellore, Tamil Nadu, India.
Indian J Pathol Microbiol. 2019 Jul-Sep;62(3):457-460. doi: 10.4103/IJPM.IJPM_623_18.
Nephropathic cystinosis is a rare autosomal recessive lysosomal disease characterized by accumulation of pathognomonic cystine crystals in renal and other tissues of the body. Cystinosis is caused by mutant cystinosin, the cystine transport protein located in lysosomal membranes, leading to systemic deposits of cystine and resultant end organ damage. Cystinosis is rarer in Asians than Caucasians with only a handful of cases reported from India to date. Due to its extreme rarity and clinically insidious presentation in contrast to the infantile form, the diagnosis of juvenile nephropathic cystinosis is frequently delayed or overlooked. Moreover, routine processing and sectioning of paraffin embedded tissues dissolves cystine crystals, making it difficult to diagnose this condition on light microscopic examination alone, mandating electron microscopic (EM) analysis of renal biopsies for an accurate diagnosis of this condition. We describe a case of juvenile nephropathic cystinosis presenting with uveitis and photophobia in a 17-year-old Indian male, diagnosed after EM examination of the patient's renal biopsy for evaluation of nephrotic syndrome. While highlighting the diagnostic utility of EM, we describe a few histopathologic clues which can prompt inclusion of EM analysis of renal biopsies in this setting.
肾病型胱氨酸病是一种罕见的常染色体隐性溶酶体疾病，其特征是在身体的肾脏和其他组织中积聚具有病理特征性的胱氨酸晶体。胱氨酸病由位于溶酶体膜上的突变型胱氨酸转运蛋白胱氨酸转运体引起，导致胱氨酸在全身沉积并最终造成终末器官损伤。与白种人相比，胱氨酸病在亚洲人中更为罕见，迄今为止印度仅报告了少数病例。由于其极为罕见，且与婴儿型相比临床表现隐匿，青少年肾病型胱氨酸病的诊断常常延迟或被忽视。此外，石蜡包埋组织的常规处理和切片会溶解胱氨酸晶体，使得仅通过光学显微镜检查难以诊断这种疾病，因此需要对肾活检组织进行电子显微镜（EM）分析才能准确诊断。我们描述了一例17岁印度男性青少年肾病型胱氨酸病患者，该患者因葡萄膜炎和畏光前来就诊，在对其肾活检组织进行EM检查以评估肾病综合征后得以确诊。在强调EM诊断价值的同时，我们描述了一些组织病理学线索，这些线索可促使在此情况下对肾活检组织进行EM分析。
