Page 316 - SAHCS HIVMed Journal Vol 20 No 1 2019

Page 5 of 7 Original Research

Unique diagnosis on bone marrow examination predictor of a unique diagnosis. More advanced HIV disease,
with a lower CD4 cell count, was found to be an additional
Positive results on BME were found in 48.3% of cases, which predictor of a positive BME in some international studies. 3,13
highlights the important persistent utility of BME in the Keiser et al. and Luther et al. both found that a haematocrit
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investigation of patients with advanced immunosuppression < 25% and 30%, respectively, predicted positive results. This
and unexplained cytopenias, fever or the suspicion of variable; however, was not measured in the current study.
disseminated mycobacterial infection. The finding of positive
results in 48.3% of cases was marginally higher than previous Mycobacterial infection on bone marrow
studies in which diagnoses made on BME accounted for examination
25% – 47% of cases. 3,4,5,8,9,10,12,13,14,21 In the current study, 23.6%
of diagnoses made were unique to the BME. This finding was Just over one-fifth of the unique diagnosis observed on BME
similar to the 24.9% unique diagnoses on BME found by resulted from confirmed MTB infection (22.1%). This finding
Karstaedt et al. ; furthermore, this is also higher than highlights the persistent utility of the BMEs in diagnosing
3
international studies in which the prevalence of unique MTB despite the introduction of the Xpert MTB/RIF testing
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diagnoses has ranged between 8% and 10%. 3,13 Van Schalkyk in early 2011. GeneXpert MTB/RIF testing of sputum has a
et al., however, had an even higher yield of 33% unique reported sensitivity of 88% and a specificity of 99%.
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diagnoses in their cohort of 147 patients. The higher yield of Between 2012 and 2014, 690 435 Xpert MTB/RIF tests had
unique diagnoses across South African studies may reflect been performed in Gauteng with the diagnosis of MTB
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the fact that in the developing world because of resource made in 12% of cases. Despite access to this useful
constraints this investigative modality is not widely available investigative modality being available at the CMJAH during
and, therefore, more consideration is given prior to the study period, we demonstrate that the BME still had
performing a BME, thus those investigations that are utility to not only aid with diagnosis of MTB but also
performed are more likely to yield a positive result. Despite provide additional diagnoses that may not have been
this, the study’s findings may be important to those clinically suspected such as malignancies. An additional
practitioners in resource-constrained areas of SA as a guide consideration is that many ill patients are unable to provide
as to which patients are likely to benefit from BME to aid good quality sputum samples. Although induction of
with diagnosis. sputum may be attempted if this is unsuccessful, the
availability of alternative diagnostic means such as BME is
The predominant unique diagnosis made on BME in the necessary. In recent years, the urine lipoarabinomanin
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current study was that of MTB, which encompassed 22.1% (urine LAM) test has become available as another modality
(17/77) of BMEs with a unique diagnosis. This finding is in to aid diagnosis of disseminated MTB infection; however,
agreement with the findings by both Van Schalkwyk et al. this testing modality was not available at our centre at the
4
and Karstaedt et al., which also revealed MTB as the time of the study and its influence on the future necessity of
3
predominant unique diagnosis on BME. Brooke et al. in BME is still to be determined.
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5
1997 reviewed 215 bone marrow samples over a 9-year period
in London and similarly found MTB as the predominant Granulomata on bone marrow examination
diagnosis (20% of all cases). In 57 cases granulomata were the only positive finding on the
BME. Although there are potentially multiple causes of
Other unique diagnoses found in the current study, which granuloma on BME, in the setting of advanced HIV and with
were similarly found in other studies, were disseminated a clinical suspicion of MTB in 32% of cases, the presence of
MAC, haematological malignancies and disseminated granuloma in the clinical setting would add value in assisting
cryptococcosis. 11,14,21 Most international studies, however, with the decision to possibly initiate a patient on empiric
found the prevalence of MAC to be higher than that of MTB, MTB treatment. Lin et al., in their study based in Taiwan,
12
reflecting differing disease profiles of mycobacterial infection found that patients with MTB infection were more likely to
in developing countries like SA in which MTB is predominant have granulomata on BME than those with non-tuberculosis
versus the developed countries in which MAC appears to be mycobacterial infections (82% compared to 30% of their 24
a more common diagnosis on BME. 22 patients; p = 0.03). This finding together with the high
prevalence of HIV positive patients with lower CD4 cell
Predictors of a positive bone marrow counts possibly accounts for the higher prevalence of
examination result granulomata observed on BME in South African studies.

This study found that a WCC ≤ 4 × 10 /L was a positive Riley et al. found that there were no positive MTB stains on
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predictor of a unique diagnosis on BME (p = 0.002). A BME in the absence of granulomata leading to their
neutrophil count of ≤ 0.5 × 10 /L, although found more suggestion that the ZN stain is of no use in the absence of
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commonly in those with a unique diagnosis, was not found granulomata. A similar finding was observed in our study
3
to be significant. Karstaedt et al., similar to our study, found with 48 patients having both a positive ZN stain and
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that a WCC < 4 × 10 /L predicted a unique diagnosis. Van granulomata observed on BME as compared to three patients
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Schalkwyk et al. found that a neutrophil count < 0.5 × 10 /L with a positive ZN stain and no granulomata observed on
predicted a unique BME result; however, that study BME. Despite this difference, the presence of a concurrent
additionally found that a Hb < 6 g/dL was also a significant positive ZN stain increases the index of suspicion that the
http://www.sajhivmed.org.za 309 Open Access