Paraffin ‘donor’ blocks were selected for each case. Using a manual tissue arrayer (MTA-1, Beecher Instruments, (Sun Prairie, WI) 0.6 mm cores were transferred from each donor block to a blank recipient paraffin block and arrayed in triplicate by one of the authors (RRS). Use of decalcified blocks could not be avoided in 65% (66/102) cases. For chondroid chordomas, whenever possible, at least one core was obtained from chondroid predominant areas, and one core from more conventional appearing areas. The cores from the donor block were annealed to the recipient block by heating to 37°C for 5 minutes and gently pressing on a flat surface to make all cores level. Paraffin sections from the constructed tissue microarray block were cut (without tape transfer) and incubated with commercially available antibodies for S-100 protein, cytokeratin cocktail AE1/AE3, brachyury, EMA, CD24, podoplanin, ()GFAP, polyclonal ()CEA, and SOX-9. Antibodies, dilutions, company and pretreatment are summarized in Table 2. Staining was visualized using the ImmPRESS™ (Vector Labs, Burlingame, CA) detection system with 2 - diaminobenzidine (DAB) as the substrate chromogen.