Bone marrow morphological features and diagnostic value in paediatric disseminated tuberculosis in the setting of...

Disseminated tuberculosis (TB) is a life-threatening condition which is often a challenge to diagnose. When to use bone marrow biopsies to diagnose disseminated TB in paediatrics is always a dilemma, from both a clinical and laboratory perspective, as there are no clear guidelines. Our study primarily aims to evaluate the role of routine bone marrow biopsies, and to compare peripheral blood cultures to aspirate cultures in the diagnosis of disseminated TB, in a paediatric population at Tygerberg Hospital. In addition, we set out to assess the morphology of bone marrow biopsies in this study.

A prospective study, consisting of 35 paediatric patients, was conducted from October 2007 to November 2008. Bone marrow aspirate and trephine biopsies were performed on all patients and examined. Granulomas with Ziehl-Neelsen (ZN) positivity were sought on the trephine biopsy for the presence of acid-fast bacilli (AFB).

Of the 35 children in this study, 25 were eventually diagnosed with TB on the basis of a multitude of clinical and laboratory parameters. The remaining 10 had alternative diagnoses. Peripheral blood TB cultures were positive in less than 1%. Bone marrow aspirate cultures were positive in less than 5%. Bone marrow trephine biopsies showed granulomas with ZN positivity in 11% of the 35 patients.

Our results, generally, agree with the current evidence. Bone marrow biopsies in children should be performed if there is a strong clinical suspicion of disseminated TB, when no alternative non-invasive confirmatory test is available.