Discrepancies have been reported in differential cell counts according to the diverse processing methods used in bronchoalveolar lavage (BAL) fluid management. The differences have proved to be mainly the result of selective lymphocyte loss, while the exact mechanisms of the phenomenon remain controversial. Observing a similar variation in differentials from differently stained identical smears, we quantified the cell loss due to staining procedures from 45 consecutive satisfactory BAL procedures. To do this, we compared relative lymphocyte recovery on neat pooled lavage in a hemocytometer with that from smears and cytopreps fixed and stained in different ways. We found (1) A significant lymphocyte loss (p < 0.05) whatever the staining method. (2) Different methods of fixation and staining lead to considerable variation in differentials from slides otherwise identically managed. The loss is higher during air-drying fixation followed by staining with an aqueous medium such as Diff-Quik than on spray-fixed slides stained in an alcohol medium such as Papanicolaou stain. (3) The effect of lymphocyte loss on differentials is more important when the initial lymphocytosis is less than 35%, and decreases to nonsignificance when it exceeds 70%. The role of cytocentrifugation or other manipulations in cell loss probably has been overestimated because unknown effects of staining methods were also attributed to these manipulations. We suggest that lymphocyte loss could arise from poor adherence on slides, which is exacerbated during aqueous staining if no artifice (e.g., spray fixation), is used to hold them. Thus, the definition of the long-awaited standard procedure for an accurate differential count of BAL fluid must take into account fixation and staining methods.
The recent occurrence of three similar cases in the same ethnic group from Niger, three from consanguineous parents, suggests that genetic factors are likely to contribute significantly to the genesis of this syndrome, consistent with a recent report that mutation of the bovine NHLRC2 gene resulting in a V311A substitution at a highly conserved locus in the NHLRC2 protein is, when homozygous, causally associated with several forms of polymelia including notomelia, with heteropagus conjoined twinning and with other NTD-related embryonic malformations. Detailed genome-wide studies of children with dysraphic appendages are indicated.
This type of tumor is extremely rare and is only the second case that has been reported at this exact location. This could be the so-called céphalomélie described by Isidore Geoffroy Saint-Hilaire in a duck in his famous Treatise of Teratology (1836). The cause of this malformation is still a matter for debate.
In the original publication of this article, we wrote "Although the allele prevalence of this V311A NHLRC2 mutation in the registered Angus cattle population was only 16% at the time, eleven of 13 consecutive cases with NTD related lesions were homozygous for the NHLRC2 mutation, demonstrating a causal association (Denholm et al., 2015)."In fact, Denholm et al. (2015) stated that the allele prevalence in the registered Angus cattle population in Australia in which the eleven consecutive NTD cases were observed was 7% at the time. (Correlation between the detected NHLRC2 mutation and the observed NTD related phenotypes is higher at the lower (corrected) allele prevalence value.)The online version of the original article can be found at http://dx
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