RT Journal Article SR Electronic T1 Characterisation of subpopulations of myeloid cells in infantile haemangioma JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 571 OP 574 DO 10.1136/jclinpath-2014-202846 VO 68 IS 7 A1 Elysia M S Tan A1 Daria A Chudakova A1 Paul F Davis A1 Helen D Brasch A1 Tinte Itinteang A1 Swee T Tan YR 2015 UL http://jcp.bmj.com/content/68/7/571.abstract AB Aims Cells expressing markers of mast cells, macrophages and dendritic cells have previously been demonstrated within the interstitium of infantile haemangioma (IH). This study characterised these myeloid cellular subpopulations within IH.Methods Immunohistochemical staining was performed on proliferating and involuted IHs for the expression of Nanog, tryptase, CD163, DC-SIGN and CD45. The presence of mRNA corresponding to Nanog, tryptase α/β-1, tryptase β-2, CD163 and DC-SIGN was confirmed by NanoString and RT-PCR in snap-frozen IH tissues.Results Immunohistochemical staining showed expression of Nanog by interstitial phenotypical mast cells within proliferating IH, which were separate from the interstitial M2-polarised macrophages that also expressed DC-SIGN, a dendritic cell marker. These two myeloid cellular subpopulations in IH did not express the pan-haematopoietic marker, CD45.Conclusions There are two interstitial subpopulations of myeloid cells within IH: phenotypical mast cells which also express Nanog, indicating a primitive phenotype; and M2-polarised macrophages which also express DC-SIGN.