Influence of preanalytical variables on performance of delta-like protein 3 (DLL3) predictive immunohistochemistry

A Quality Analysis of Bony Specimens for Optimal Ethylenediaminetetraacetic Acid (EDTA) Decalcification

Introduction: Weak acids, such as etheylenediaminetetraacetic acid (EDTA), chelate calcium ions from the surface of tissues, decalcifying slowly but preserving molecular structures for ancillary testing. There is a need for optimization of EDTA protocols for specimen decalcification. We studied the effects of EDTA on different types of bony specimens for quality assurance. Methods: Specimens included: proximal femur curettage (0.7 g), fibula shave (1 mm thick, 0.5 g), tibia shave (2 mm thick, 0.9 g), and femur 11-gauge core biopsies. Curettage and shave specimens were placed in formalin then EDTA (Newcomersupply, Middleton, WI, USA) with continuous stirring. Specimens were removed at 24, 48, 72, 96, and 120 hours. Core biopsies were processed in EDTA with heat at 4, 8, 12, and 16 hours. X-ray imaging (Kubtec Xpert 40, Stratford, CT, USA) was obtained. Histological processing was attempted and H&E slides compared to radiologic imaging. Results: Fibula and tibia sections showed appropriate radiolucency at 120 hours and 7 days, respectively. Curettage specimens showed radiolucency of medullary bone at 48 hours. Curettage and fibula sections showed quality histology at 96 hours and 120 hours, respectively. Quality tibia sections were obtained at 7 days, requiring one hour of additional block surface decalcification with 1% HCL solution. Medullary and cortical core biopsies showed quality histology at 12 and 16 hours with heat, respectively. Conclusion: Imaging can determine appropriate decalcification of bony specimens. Medullary bone undergoes more rapid decalcification in EDTA than cortical bone. EDTA decalcification is best used for curettage and core biopsy specimens.