The cellular microenvironment and neoplastic population in mycosis fungoides skin lesions: a clinicopathological correlation.

The cellular microenvironment has been proven to play a crucial role in solid tumours and seems to be important in haematologic malignancies, however, it has not been adequately investigated in primary cutaneous T cell lymphomas. The aim of this study was to register the composition of the cellular microenvironment in mycosis fungoides skin lesions and correlate the composing parameters with the clinical data and follow-up results. The presence of eosinophilic polymorphonuclear leukocytes, B lymphocytes, CD68 ⁺ macrophages, and CD1a ⁺ epidermal Langerhans and antigen-presenting dermal dendritic cells, as well as their relation to clinicopathological parameters, were studied in 16 mycosis fungoides cases of different disease stages. The presence and nature of the participating T cell populations was also investigated. CD8 ⁺ tumour infiltrating T cells and CD56 ⁺ cells were found among neoplastic CD4 ⁺ T cells in the lesions. Generally, eosinophils and B lymphocytes were absent or in low numbers, regardless of clinical presentation, contrary to tumourous lesions. Macrophages and CD1a ⁺ cells were constantly present, even in early-stage mycosis fungoides. The reduced presence of the CD1a ⁺ population was associated with resistance to therapy (x ² ; p = 0.012). There is a striking difference in cellular microenvironment composition between early and advanced mycosis fungoides lesions.