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Heparin and chondroitin sulfate are both proteoglycans. Therefore, we carried out this study to examine whether heparin-like granular deposits, which frequently impair the morphological assessment of bone marrow touch preparations, could result from the inclusion of cartilage in the bone marrow biopsy.
Touch imprints were made from bone marrow biopsies taken from the posterior superior iliac spine using Jamshidi needles.1,2 Bone marrow touch preparations were stained with Jenner Giemsa, and decalcified bone marrow biopsies were stained with haematoxylin and eosin.
Two hundred and twenty consecutive bone marrow touch preparations and the corresponding biopsies were evaluated for the presence of purple granular deposits and cartilage, respectively. Inspection of trephine biopsies for cartilage was done without knowledge of the touch imprint findings.
The χ2 test was carried out to test whether granular deposits and/or bone marrow biopsy cartilage were more common in children than in adults.
One hundred and ten of the 220 touch preparations had purple granular deposits. One hundred and five cases were free of such deposits. Five cases were interpreted as equivocal with regard to granular deposits.
Samples that were positive for deposits had large numbers of fine to coarse granules, which were located extracellularly (figs 1 and 2). These could pose a significant problem in interpretation, particularly in bone marrows that were not normal or had leukaemic infiltrates. All the 110 positive cases had cartilage in the bone marrow biopsies; there was one case in which cartilage was not observed initially, but was seen when further sections were taken from the biopsy
The five cases that were equivocal on bone marrow touch showed cartilage in the bone marrow biopsy. The touch preparation in these cases had minimal granular deposits. The findings appeared suggestive, but not definitive, for the presence of cartilage. However, their similarity with the sparsely granular appearance at the periphery of florid deposits showed that the equivocal appearance, too, was probably of cartilaginous origin.
In none of the 105 cases where the bone marrow touch preparation was free of granular deposits was cartilage seen in the biopsy.
Among the 220 patients, 83 were children (⩽ 15 years). Of these 83, 68 were positive for granular deposits and cartilage, whereas the remaining 15 were negative for both. When the proportion of children who had (68) or did not have (15) granular deposits was compared with the corresponding figure for adults (47 and 90, respectively), the difference, evaluated by the χ2 test, was significant (p < 0.0001).
In no case were crush artefacts observed.
Purple granular deposits that obscure morphology and make the satisfactory evaluation of bone marrow touch preparations difficult or at times impossible are of common occurrence in our experience, although surprisingly, to the best of our knowledge, are not mentioned in the published literature.1–5
Our results very clearly demonstrate that purple granular deposits, generally dense, in bone marrow touch preparation appear only if cartilage is included in the bone marrow biopsy. The odd case with apparently no cartilage results from the orientation of the bone marrow biopsy, such that a particular section may fail to include the cartilage. In contrast, the presence of only equivocal sparse granularity in a sample containing cartilage can be explained by the proportion constituted by, and the position of, the cartilage within the biopsy, and the way it has been touched on to a slide.
The high frequency of cartilage in the trephine bone marrow biopsy of children has been documented previously,4 and explains the more common occurrence of granular deposits in biopsies from children. The absence of crush artefacts on the touch preparations showed that excess force was not used when making imprints.
The importance of this observation lies in the fact that not only are bone marrow biopsies commonly performed, but the touch preparation made from them may at times be the most important resource for the evaluation of morphology, cytochemistry, or immunocytochemistry.3 This may occur, for instance, when fibrosis or a densely cellular bone marrow make the bone marrow aspiration unsatisfactory.4 In our cancer centre, where bone marrow biopsy with touch imprint rather than aspiration is the commonly performed procedure, this artefact at times impedes swift reporting of the bone marrows.
We conclude that purple granular deposits that impair the evaluation of bone marrow touch preparations are a result of the presence of cartilage in the bone marrow biopsy, and are seen more often in children.
Help from Dr R Gupta in this work is acknowledged.