Stromal Cells with Telocyte-Like Characteristics in the Ethmoidal Mucosa: Immunohistochemical Characterisation and Methodological Considerations

Background Telocytes (TCs) are specialised stromal cells characterised by extremely long, thin, moniliform cytoplasmic processes (telopodes). Although described in multiple organs, they have not been investigated in the sinonasal mucosa. This study provides preliminary immunohistochemical characterisation of stromal cells with TC-like morphology in human ethmoidal mucosa (SCs/TCs). Methods Paraffin-embedded ethmoidal mucosa from seven patients undergoing sinus surgery was analysed using immunohistochemistry with eight markers (CD34, vimentin, α-SMA, smooth muscle myosin heavy chain, CD10, nestin, von Willebrand factor, HER-2). Morphological qualification criteria for SCs/TCs were: (1) processes > 50 μm, (2) moniliform contour with podoms/podomeres, (3) absence of lumina excluding sectioned endothelium, and (4) markedly thinner calibre than endothelial tubes. Cells that fulfilled these criteria and expressed mesenchymal markers were classified as TC-like. Results CD34+/vimentin+/α-SMA+/CD10 − SCs/TCs were identified, with telopodes exceeding 50 μm (mean 78.4 ± 24.6 μm) and forming interconnected networks (density 12.3 ± 3.7 cells/mm²) embedded among microvessels. Subpopulations showed myoid differentiation (smooth muscle myosin+, ~ 19%) or HER-2 expression (~ 12%). Detailed morphological evaluation allowed distinction from false TC appearances generated by tangentially sectioned CD34 + endothelium, which consistently showed CD10+/vWF+/nestin+ phenotypes. Conclusions This pilot study provides preliminary evidence of stromal cells with TC-like characteristics in the human ethmoidal mucosa and establishes practical morphological criteria for their light-microscopic identification. Occasional HER-2 expression indicates possible phenotypic heterogeneity but requires functional validation. Definitive classification as TCs and clarification of their physiological or pathological roles will require co-labelling and ultrastructural confirmation.