Background: The diagnostic utility of repeat kidney biopsy in AL amyloidosis patients in complete (CR) or very good partial hematologic response (VGPR) but with renal organ relapse is not clear.Methods: We present eight patients with AL amyloidosis who had a repeat kidney biopsy performed.Results: AL amyloidosis was initially diagnosed by a kidney biopsy. All patients had a favorable response to treatment (CR/VGPR) and five of them also had initially a renal organ response. A repeat kidney biopsy was done due to gradual deterioration of kidney function and/or proteinuria while maintaining a hematologic response. Repeat kidney biopsies showed findings consistent with amyloid deposits in all patients. Seven patients had renal progression with four of them requiring dialysis initiation. Only one patient had a favorable renal outcome. This patient had subacute kidney injury with decreasing proteinuria and was found to have granulomatous interstitial nephritis in addition to amyloid deposits and responded well to steroid treatment with rapid improvement in renal function.Conclusions: In AL amyloidosis patients who achieve a favorable hematologic response to treatment (CR/VGPR) but subsequently develop worsening renal insufficiency or proteinuria, a repeat kidney biopsy should generally not be performed. Amyloid deposits persist in the kidneys even after successful hematologic treatment and it is impossible to differentiate between new versus old amyloid deposits, which makes performing a repeat kidney biopsy unnecessary in most cases. Demonstration of amyloid deposits on repeat kidney biopsy would not aid in the decision making regarding re-initiation of hematologic treatment. A kidney biopsy should be considered only in cases when a specific alternative diagnosis is suspected.

中文翻译：

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重复肾活检在全身免疫球蛋白轻链淀粉样变性中的应用。

背景：对于完全（CR）或部分血液学很好（VGPR）但肾器官复发的AL淀粉样变性患者，进行肾脏重复活检的诊断作用尚不清楚。方法：我们目前有八名患有肾脏重复性AL的淀粉样变性患者结果：AL淀粉样变性最初是通过肾脏活检诊断出来的。所有患者对治疗的反应均良好（CR / VGPR），其中五名患者最初也出现了肾脏器官反应。由于肾脏功能和/或蛋白尿逐渐恶化，同时又维持血液学反应，因此进行了重复肾脏活检。重复进行肾脏活检显示所有患者的淀粉样蛋白沉积结果一致。七名患者有肾脏进展，其中四名需要开始透析。只有一名患者的肾脏预后良好。该患者患有亚急性肾损伤，蛋白尿减少，除淀粉样蛋白沉积外还患有肉芽肿性间质性肾炎，对类固醇治疗反应良好，肾功能迅速改善。 CR / VGPR），但随后发展为肾功能不全或蛋白尿恶化，通常不应进行重复的肾脏活检。即使在成功的血液学治疗后，淀粉样蛋白沉积物仍会保留在肾脏中，并且无法区分新的和旧的淀粉样蛋白沉积物，这使得在大多数情况下无需进行重复的肾脏活检。重复进行肾脏活检证明淀粉样蛋白沉积无助于重新开始血液治疗的决策。