Construction of a tissue microarray with two millimeters cores of endometrioid endometrial cancer: factors affecting the quality of the recipient block.

The tissue microarray (TMA) method currently is not used to render a primary diagnosis of cancer, but its scientific value has been proved in studies of various cancer types. TMA technology still is not used often for uterine tumors, however. We investigated the repeatability of histological diagnosis of endometrioid endometrial cancer (EEC) using conventional histology and TMA using 2 mm cores. We examined EEC tissues from 171 patients. Formalin fixed, paraffin embedded tissue donor blocks from EEC specimens were selected and examined histologically. Duplicate 2 mm tissue cores were inserted into a TMA recipient block. EEC tissues were examined as hematoxylin-eosin stained sections from the TMAs. EEC tissue was identified in the TMAs in 158 cases (92.4%) and not found in 13 cases (7.6%). On the TMA slides, both EEC positive cores were identified in 129 cases (75.4%), but only one core in 29 cases (17.0%). Among 342 biopsies of the donor blocks (each case in duplicate), EEC was found in 287 cases (83.9%) using the TMA: 124/146 (84.9%) with superficial infiltration, 153/178 (86.0%) with deep myometrial infiltration, and 10/18 (55.6%) without myometrial infiltration. We concluded that two 2 mm tissue cores from a biopsy of a donor block inserted into a TMA recipient block were sufficient to diagnose EEC in more than 90% of cases. EEC was identified in the TMAs with similar frequency with respect to superficial and deep myometrial infiltration. Cases without myometrial infiltration were identified less often.