Expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) is important in predicting a response to targeted therapies in breast cancer. Immunohistochemical assays to determine hormone receptor (HR) and HER2 status must therefore be accurate and reproducible. Tissue fixation has been shown to play a crucial role in determining consistency in quality. Although guidelines impose upper limits for the fixation period, the data on which these limits are based are scant. This study aimed to prospectively examine the effect of fixation of >72 hours on these assays. In 101 invasive breast cancer samples, HR and HER2 status was compared between tumor blocks undergoing a short fixation period with those undergoing a period of prolonged fixation (PF). Discordances were classified as an incremental change between categories of (i) a single order of magnitude, that is a difference in the status of low positive (Allred score 3) compared with positive (Allred score 4 to 8) or negative (Allred score 0 or 2) and vice versa for HRs and a difference in HER2 status of equivocal compared with negative or positive and vice versa or (ii) greater than a single order of magnitude, that is a difference in the status of positive compared with negative or vice versa. The median fixation time for the short fixation group was 13 hours and 18 minutes (mean, 13 h 17 min; range, 10 h 33 min to 17 h 45 min) and for the PF group was 79 hours 22 minutes (mean, 79 h 35 min; range, 73 h 33 min to 102 h 30 min). Eight cases showed discordances, all of which were of a single order of magnitude including 1 for ER, 5 for PR, and 2 for HER2. In 6 of these, a higher score was seen in the PF group. In conclusion, fixation for limited periods beyond 72 hours does not result in a reduction in assay sensitivity in the determination of ER, PR, or HER2 immunohistochemical status.

Background: Thirty-one gliosarcomas (25 nonirradiated and 6 postirradiated tumors) were selected based on the presence of two distinctive areas: a malignant gliomatous and a sarcomatous component. In all cases, the sarcomatous component appears like fibrosarcoma or malignant fibrous histiocytoma. Two tumors showed additional areas consisting of osteochondroid differentiation. Methods: All tumors were examined using antibodies against Ulex europaeus agglutinin I (UEA), glial fibrillary acidic protein (GFAP), vimentin (VM), epithelial membrane antigen (EMA), desmin, collagen IV, alpha-1-antitrypsin (a-l-AT) and smooth muscle actin (SMA). Results: While the VM highlighted the sarcomatous areas of all tumors there were only scattered spindle cells that were GFAP-positive in the same areas. The a-l-AT was diffusely reactive in the sarcomatous areas in 20 cases. Focal immunoreactivity was seen with SMA (20 tumors), UEA (8 tumors), EMA (5 tumors), collagen IV (5 tumors) and desmin (4 tumors) in the nonvascular sarcomatous cells. Conclusions: The range of immunophenotypical expression is likely to be a reflection of the capacity of a multipotential progenitor to undergo divergent differentiation. There is very little morphological difference between the postirradiated and nonirradiated tumors except that a higher proportion of postirradiated tumors are immunoreactive to SMA and desmin.