BONE-MARROW FIBROSIS - HISTOMORPHOMETRIC ANALYSIS AND INTEROBSERVER REPRODUCIBILITY OF A SIMPLE OPTICAL METHOD OF ASSESSING ITS INTENSITY

A histomorphometric analysis of the length of reticulin fibres per are a of haemopoietic bone marrow was performed on 59 trephine iliac crest biopsies. The values obtained were found to correlate with the degree of fibrosis as determined by a simple optical method based on the deg ree of microscopic magnification required for recognition of the prese nce of reticulin fibres. The mean length of fibre (mum/10000 mum2) for the three degrees of fibrosis defined by the optical method were: 241 .8 +/- 16.6 for grade I, 713 +/- 8 5.6 for grade II, and 1827.9 +/- 23 0.4 for grade III (P < 0.001). In a series of 67 biopsies, the overall interobserver agreement of the optical method was found to be good (S pearman's r = 0.99; P < 0.001) and there was good individual agreement for each of the three degrees of fibrosis (improved kappa test). Ther e was a small amount of overlap between the extreme values of adjacent optical degrees. These results suggest that the optical method descri bed here can be recommended as a practical technique for the routine e valuation of myelofibrosis.