The histological spectrum of tubulo-reticular inclusion positive renal biopsies: a tertiary hospital experience and review of the literature

Aim: To identify the underlying diseases with TRI-positive kidney biopsies, and describe the histological pattern and spectrum of TRI-positive kidney biopsies.

Methods: A retrospective analysis of all patients’ chart that underwent renal biopsy at King Saud University Medical City between 2012 and 2017 was done. Kidney biopsies that indicated a positive result for tubuloreticular inclusions (TRI’s) on electron microscopy were reviewed and the underlying disease and histological pattern was extracted.

Results: Of 1,473 native kidney biopsies reviewed, 96 (6.5%) were TRI-positive. Of the 96 TRI-positive kidney biopsies, 87 (90.6%) were TRI-positive lupus nephritis (LN); of which 10 (11.5%) were Class V, 49 (56.3%) were active LN, and 28 (32.2%) were inactive LN. The underlying diseases of the nine non-LN TRI-positive cases included diabetic nephropathy, connective tissue disorders, immune complex mediated Glomerulonephritis (GN), acute thrombotic microangiopathy, rhabdomyolysis, and Wegener’s disease.

Conclusion: LN is a very common finding in TRI-positive kidney biopsies. Active LN and chronic LN are the more common classes of TRI-positive LN kidney biopsies, than pure membranous (Class V) LN. TRI positive kidney biopsies without LN are commonly found in diabetic nephropathy, connective tissue disorders and immune mediated GN’s.

This study highlights this finding in our patients cohort in opposition to what has been reported in the literature.