Utility of left-over renal tissue for light microscopy after immunofluorescence

Sir,

We read the article “retrieval of kidney tissue for light microscopy (LM) from frozen tissue processed for immunofluorescence (IF): A simple procedure to avoid repeat kidney biopsies” by Tyagi et al., with the interest.[1] In our institute, we also usually receive two cores of renal tissue, one in buffered formalin for LM and the other in normal saline for IF. Usually, we process both the tissue simultaneously. We have received adequate renal tissue, most of the time. But occasionally, there are cases where we have faced a similar situation as described by the authors, where glomeruli were present in IF sections, but absent in LM sections. In those instances, we have processed the left over frozen tissue originally sent for IF by fixing it with formalin for 2 hours. In our experience, we also have observed that crescents are easily diagnosed in the processed left over frozen IF tissue, thereby helping in arriving at the diagnosis and avoiding the necessity of repeat renal biopsy. So, in our opinion, in cases where renal biopsy is inadequate in LM sections, the left over frozen tissue can be processed to look for glomeruli, before asking for repeat renal biopsy.