Objective: To investigate the possibility of glomerular retrieval from formalin left in biopsy vials and to evaluate its diagnostic value and accuracy.
Study design: Cell blocks were prepared from 94 consecutive formalin vials left after processing of renal biopsies from 93 patients, including 25 transplant patients. The prepared cell blocks were processed with routine biopsies and evaluated separately, and the results compared.
Results: Of the 94 samples, 29 (23 nontransplant patients and 6 allograft recipients) showed the presence of glomeruli in cell blocks, with an average of 1.7 glomeruli per cell block. In nonallograft native renal biopsies, the histologic diagnosis of glomerular morphology in cell blocks correlated with routine biopsy in 18 of 22 cases. The least retrieval was seen in crescentic glomerulonephritis, diabetic glomerulosclerosis and diffuse global glomerulosclerosis, possibly due either to the tight adherence of the glomerular tuft to the crescent or to fibrosis. All 6 samples from transplant recipients showed normal glomeruli in routine histology and in cell block preparations.
Conclusion: Cell blocks from discarded formalin may be a useful adjunct to routine histopathology for the diagnosis of glomerular disease in centers where inadequacy of renal biopsy is frequently reported.