RESUMO
NK/T cell lymphoma, nasal type is an aggressive and uncommon malignancy. Disease that occurs outside of the aerodigestive tract exhibits an even more aggressive clinical behaviour and does not respond as well to conventional therapy compared to its nasal counterpart. We report such a case of NK/T cell lymphoma, nasal type, that presented as an anterior chest wall mass, arising from the left pectoralis muscle. An interesting feature we wish to highlight is the associated eosinophilia that corresponded to disease activity, exhibiting fluctuations with surgical resection and chemotherapy. To the best of our knowledge this is the third reported case of NK/T cell lymphoma that is associated with peripheral eosinophilia. Our case highlights the role of certain NK cell subsets that play a major role in eosinophilic activation in NK/T lymphomas and calls for more research into further classification of this disease by virtue of its NK cell subsets.