J. H. F. Smith

Does delay in fixation affect the number of mitotic figures in processed tissue

The effect of delay in fixation on the number of mitotic figures in tissues has received little attention, and previous studies have reached differing conclusions. The numbers of mitotic figures in the normal mucosa of six colectomy specimens were counted with delays in fixation of 30 minutes, one hour, two hours, three hours and six hours for samples from each specimen. The numbers of mitotic figures were counted in 50 whole crypts in each specimen by two observers. All phases of mitosis were counted. The number of observable mitotic figures declined by about 30% with a delay in fixation of two hours and by 50% with a delay of six hours. This observation has important implications for the handling of surgical specimens.

Reassessment of the rate of fixative diffusion.

The diffusion of fixatives is slow. Early work using plasma gels and animal tissues showed the distance penetrated by a fixative to be a simple function of the fixation time but this relation has not been established in human tissues. The rates of diffusion into whole human spleens were measured for three primary fixatives over periods ranging from one to 25 days. A positive correlation was demonstrated between penetration distance (mm) and fixation time (hours). The diffusion rates were slower than those in previous studies. These results have possible implications for the handling of surgical specimens.

Is the grading of breast carcinomas affected by a delay in fixation

The effect of delay in fixation on the modified Bloom and Richardson grade of eight breast carcinomas was investigated. Topologically shuffled samples of each tumour were immersed in fixative at times of 0.5, 2, 4, 6, 18 and 24 h after surgical removal. The grade of each tumour was assessed at delays of 0.5 and 6 h. The tubule formation and nuclear pleomorphism components of the grade showed no change with a delay in fixation of 6 h. The number of mitotic figures declined by a mean of 53% over the same period and this resulted in a decrease in the histological grade of one of the tumours. The implications of these findings for the handling of breast specimens in a diagnostic histopathological laboratory are discussed.

Is there any justification for the routine examination of bowel resection margins in colorectal adenocarcinoma

The proximal and distal bowel resection margins of 339 specimens of colorectal adenocarcinoma were examined for the presence of tumour. In only five cases was tumour found in a resection margin. In four of these cases macroscopic examination showed that the tumour extended to the resection margin. In the fifth case the tumour was present in the pericolic fat. These results and reported data on the intramural spread of colorectal cancer suggest that examination of bowel resection margins is unnecessary unless the tumour extends to within 2 cm of the resection margin. Examination of the deep radial margins of the tumour and slides to show other prognostic indicators would be a more effective use of histopathological resources.

Educational Case Report Cervical cytology through the looking glass

A 25‐year‐old woman underwent a routine cervical smear that was reported as showing borderline change. Six months later when 6 months pregnant she had a repeat smear. This is shown in Figure 1 (Pap., original mag. × 600.)