Abstract
Extranodal natural killer/T cell lymphoma, nasal type (ENKL) is a rare and aggressive tumour that can, clinically and histologically, mimic infectious and inflammatory conditions, presenting a diagnostic challenge. The authors report the case of a 69-year-old Portuguese woman previously misdiagnosed with chronic recurrent sinusitis. Despite maximal medical and surgical treatments, the disease was refractory and progressed. The patient had undergone multiple biopsies when the histopathological diagnosis of ENKL was made, 5 months after the initial complaints. Multiagent chemotherapy was offered, but during the first cycle, the patient developed severe infection and pancytopenia, which culminated in her death. This case highlights the need to consider a neoplastic cause when faced with aggressive sinonasal disease not responsive to maximal treatment and the difficulties in establishing the diagnosis of ENKL, with multiples biopsies of deep-tissue usually being required.