Impaired Kidney Function with Renal Tubular Vacuolization and Paracrystals in Adult Refsum Disease: A Case Report
Bibliographic record
Abstract
Introduction: Classic, or adult, Refsum disease (ARD) is a rare peroxisomal disorder characterized by an inability to metabolize the fatty acid phytanic acid (PA). Accumulation of PA leads to polyneuropathy and potentially lethal cardiac arrhythmias. Renal impairment is rarely seen and there is a paucity of information on the histopathology. We present a case of renal impairment due to tubular involvement by ARD. Case Description: A 55-year-old Fijian female with genetically proven ARD presented with a reduced eGFR without proteinuria or overt tubular dysfunction . Her past medical history includes ARD-related retinitis pigmentosa, DM2, recent MI with PCI, and chronic knee osteoarthritis. Physical examination showed shortened toes consistent with ARD. Serum PA at diagnosis was 180 mcg/mL (ULN 3 mcg/mL). A renal biopsy was performed to assess for diabetic nephropathy versus another cause for her renal impairment. The biopsy showed diffuse vacuolization of renal tubular epithelium, with rare foci of intracytoplasmic crystals (Figure 1A). Ultrastructurally, these crystals were electron dense with unusual parallel linear arrays (or ‘paracrystalline formation’) (Figure 1B). She continues to be very adherent to her low PA diet and avoidance of fasting, but despite this has experienced a progressive decline in her eGFR. Her PA level remains elevated at 270 mcg/mL. Discussion: To the best of our knowledge, this is the first description of intracytoplasmic crystals on light microscopy in ARD. The etiology and pathologic effects of these crystals are not yet known, but they may share features with other crystalline nephropathies. This case provides evidence to support renal function monitoring in ARD, which is currently not suggested by the literature. The morphology of the intracytoplasmic crystals are rather distinct but subtle and can be overlooked. Nephropathologists should be vigilant for additional findings in the setting of tubular epithelial abnormalities without a known explanation. Limiting dietary PA is the first-line treatment of choice but may not be sufficient to prevent complications.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.002 | 0.002 |
| Bibliometrics | 0.005 | 0.003 |
| Science and technology studies | 0.003 | 0.002 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.002 | 0.003 |
| Research integrity | 0.007 | 0.004 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".