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• Negative images of mycobacteria
  Debdatta Basu
  Published on: 18 April 2016

• Published on: 18 April 2016

  Negative images of mycobacteria

  • Debdatta Basu, Professor of Pathology
  • Other Contributors:
    • Paari Murugan, Krishnan R Iyengar

  Dear Editor,

  We read with interest the article by Dunn et al.[1] We have reported unstained rod-shaped images of mycobacteria in Romanowsky-stained aspirate smears of lymphnodes and bone marrow in patients with AIDS.[2,3] These were subsequently confirmed to be acid-fast bacilli with Ziehl- Neelsen stain. We referred to them as ‘negative images’. Maygarden and Flanders first reported negative images of mycobacteria...

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  Dear Editor,

  We read with interest the article by Dunn et al.[1] We have reported unstained rod-shaped images of mycobacteria in Romanowsky-stained aspirate smears of lymphnodes and bone marrow in patients with AIDS.[2,3] These were subsequently confirmed to be acid-fast bacilli with Ziehl- Neelsen stain. We referred to them as ‘negative images’. Maygarden and Flanders first reported negative images of mycobacteria in patients with AIDS.[4] In addition to finding these negative images of mycobacteria within the cytoplasm of histiocytes, we have demonstrated them in the background in the extracellular necrotic debris in the lymphnode aspirate smears.[2]

  Although the authors have reported their findings in granulomas, we did not encounter granulomatous inflammation in the lymphnodes. The smears showed only degerating and viable neutrophils and macrophages in a necrotic background with negative images. This finding may be explained by the fact that all our patients were HIV positive, in whom a granulomatous response is not expected. The bone marrow biopsy, in one case, however showed ill-defined granulomas and collections of foamy histiocytes, which had plenty of intracellular negative images.

  We also contrast the findings of the authors with respect to the PAS negativity of the organisms. Papolla et al. demonstrated that in contrast to other mycobacteria, including M.tuberculosis, M.avium-intracellulare has a unique staining character of PAS positivity and acid-fastness.[5] All our cases were also PAS positive.

  The term pseudo-Gaucher cells may also be inappropriate in the sense that these cells with intracellular negative images have very few, if any similarities with the other pseudo-Gaucher cells found in conditions like Chronic Myeloid Leukemia, where there is indeed presence of increased glucocerebroside as in a true Gaucher cell.

  We do however; concur with the fact, that a diligent search for these negative images, both in the histiocytes and in the background, is a rapid and inexpensive way of detecting mycobacteria before specific results are available.

  References

  1. P Dunn, M-C Kuo and C-F Sun Pseudo-Gaucher cells in mycobacterial infection: a report of two cases. Journal of Clinical Pathology 2005;58:1113-1114

  2. Iyengar KR, Basu D Negative images in the fine needle aspiration cytologic diagnosis of mycobacterial infections. Malaysian J Pathol 2001; 23: 89-92

  3. Basu D and Nilkund J. Detecting mycobacteria in Romanowsky-stained cytologic smears: a case report. Acta Cytol 2003: 47; 774-776

  4. Maygarden SJ, Flanders EL. Mycobacteria can be seen as “negative images” in cytology smears from patients with acquired immunodeficiency syndrome. Mod Pathol 1989; 2:239-243.

  5. Papolla MA, Mehta VT. PAS reaction stains phagocytosed atypical mycobacteria in paraffin sections. Arch Pathol Lab Med 1984;108:372-373.

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  Conflict of Interest:
  None declared.

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