Abstract: FR-PO964
Clinicopathologic Features of Karyomegalic Tubulointerstitial Nephritis
Session Information
- Pathology and Lab Medicine - 1
October 25, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Pathology and Lab Medicine
- 1800 Pathology and Lab Medicine
Authors
- Caza, Tiffany, Arkana Laboratories, Little Rock, Arkansas, United States
- Larsen, Christopher Patrick, Arkana Laboratories, Little Rock, Arkansas, United States
- Kurien, Anila Abraham, Renopath Center for Renal and Urological Pathology Pvt Ltd, Chennai, India
Background
Karyomegalic interstitial nephritis (KTIN) is a very rare genetic tubulointerstitial kidney disease caused by mutations in the FAN1 gene. Less than 100 cases have been reported to date, the majority in case reports or small case series. Here, we examine a series of 16 patients of KTIN to further characterize clinical and pathologic features of the disease.
Methods
Patients with a diagnosis of KTIN were identified from renal pathology archives at Arkana Laboratories (USA) and the Renopath Center for Renal and Urological Pathology (India). Clinical data, laboratory values, and histopathology were reviewed.
Results
Sixteen patients with KTIN who underwent kidney biopsy were identified, including eight from the United States and eight from India. These included 15 patients whom had a native biopsy and one with an allograft biopsy (transplant from a sibling). There was male predominance (87.5%) with a mean age of 42 ±12 years. Five patients had a history of hypertension (31.3%) and six had diabetes mellitus (37.5%). None had a history of malignancy. Three patients had a positive family history of kidney disease. All presented with chronic kidney disease, with a mean serum creatinine of 2.9 ± 1.0 mg/dL. Nine had proteinuria of 1+ or greater, three were nephrotic range.
Kidney biopsies from all patients demonstrated acute tubular injury with markedly enlarged nuclei. There was chronic injury present in the majority of cases, with a mean global glomerulosclerosis of 31.6 ± 22.4%. There was interstitial inflammation and tubulitis seen in 12 patients, six which had only mild inflammation (10-25% cortex). Interstitial inflammation was lymphoplasmacytic in 11 and one was neutrophil-rich. All cases were negative for SV40 and CMV, ruling out viral cytopathic effects. Eight had a second kidney biopsy diagnosis, including 2 with IgA nephropathy, 2 with minimal change disease, 1 with thin glomerular basement membranes, 1 with focal segmental glomerulosclerosis, 1 with chronic active pyelitis, and 1 with T cell mediated rejection.
Conclusion
KTIN patients were predominantly males presenting in middle age with chronic kidney disease and proteinuria. The majority of patients had no greater than mild interstitial inflammation, of which is lymphoplasmacytic in character. A concurrent second kidney biopsy diagnosis was present in one-half of patients.