Megakaryocytes in pulmonary circulation: an “old” knowledge with new implications

The post-mortem pulmonary findings of a 59-year-old woman with infection by the human immunodeficiency virus and liver cirrhosis related to chronic hepatitis B are presented. The patient was admitted due to decompensated liver disease and initial laboratory data revealed anemia (hemoglobin concentration 8.8 g/dL), leukocytosis (12 × 10⁶/L) and normal platelet count (399 × 10⁹/L). The patient was receiving prolonged highly active antiretroviral therapy. No treatment directed at chronic hepatitis B, tuberculosis or anti-cancer therapy has been administered.

In post-mortem study, hemoperitoneum was identified as the immediate cause of death in association with active pulmonary tuberculosis and hepatitis B virus-associated hepatocarcinoma (TNM Staging System - IVB). Numerous megakaryocytes were detected in pulmonary circulation (Figures 1 and 2). In bone marrow evaluation, mycobacterial or fungal infections as well as cancer infiltration were not detected (Figure 3). The evidence of thrombopoiesis in lungs is not recent and innovative experiments indicate that up to half of platelet production may originate from megakaryocytes located in the pulmonary circulation.¹,²,³

Figure 1
Multiple megakaryocytes (arrows) identified in the pulmonary circulation (Hematoxylin and Eosin staining, 400 × magnification).

Figure 2
Immunohistochemistry analysis for confirmation of megakaryocytes (arrows) in lungs. Factor VIII-related antigen stain. CD61 immunohistochemistry was also positive on megakaryocytes (not shown). 400 × magnification.

Figure 3
Bone marrow biopsy shows normal global cellularity (granulocytic hypoplasia and erythroid hyperplasia) and normal megakaryocyte cellularity (2.8 megakaryocytes per high-power field [× 400] - normal range 2 to 4 per high-power field). There is no evidence of cancer infiltration, granulomas, or mycoses (Hematoxylin and Eosin staining, 200 × magnification).

References

• ¹
  Levine RF, Eldor A, Shoff PK, Kirwin S, Tenza D, Cramer EM.Circulating megakaryocytes. Delivery of large numbers of intact, mature megakaryocytes to the lungs. Eur J Haematol. 1993, 51(4):233-46. doi: 10.1111/j.1600-0609.1993.tb00637.x.
  » https://doi.org/10.1111/j.1600-0609.1993.tb00637.x
• ²
  Lefrançais E, Ortiz-Muñoz G, Caudrillier A, Mallavia B, Liu F, Sayah DM, et al. The lung is a site of platelet biogenesis and a reservoir for haematopoietic progenitors. Nature. 2017; 544(7648):105-9. doi: 10.1038/nature21706.
  » https://doi.org/10.1038/nature21706
• ³
  Borges I, Sena I, Azevedo P, Andreotti J, Almeida V, Paiva A, et al. Lung as a niche for hematopoietic progenitors. Stem Cell Rev. 2017;13(5):567-74. doi:10.1007/s12015-017-9747-z.
  » https://doi.org/10.1007/s12015-017-9747-z

Publication Dates

• Publication in this collection
  10 June 2022
• Date of issue
  2022

History

• Received
  24 Dec 2020
• Accepted
  24 Feb 2021
• Published
  24 May 2021