Abstract
Extranodal NK/T-cell lymphoma, nasal type (ENKL), is an uncommon subtype of EBV associated lymphoma usually characterized by aggressive clinical course. We report an atypical sinonasal ENKL case with long-lasting indolent behaviour, developed in the setting of a polymorphic EBV-associated lymphoproliferative disorder (LPD). A 52-year-old woman had suffered from chronic sinusitis and nasal obstruction since 2000, moderately worsened during the last years (marked enlargement of the sino-nasal mucosa at MRI in 2011) with elevated anti-VCA IgG and IgM titers. Three subsequent biopsies revealed slightly increasing morphophenotypic atypia, ranging from a polymorphic B- and T-cell EBV positive proliferation (diagnosed in 2011, but not fulfilling CAEBV diagnostic criteria) to an overt monomorphic mildly atypical T LPD without necrosis and angiocentricty diagnosed as ENKL in 2013 upon immunophenotype and TCR-γ gene clonal rearrangement. Clinically indolent ENKL with low-grade morphology is extremely rare and diagnostically challenging; while the few reports in the literature describe long-survival in ENKL treated patients comparing histologically neoplastic lesions at onset and recurrences, no reports are published on the slow progression from a polymorphic EBV-related T/NK proliferation to a histologically overt clinically indolent ENKL in an untreated patient who only received occasional steroid administration.
Highlights
Extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKL), is an uncommon subtype of lymphoma derived from NK or, less commonly, from cytotoxic T-cells, associated with Epstein-Barr virus (EBV), which usually arises in the upper aerodigestive tract [1]
We report an atypical case of sinonasal NK/T-cell lymphoma with indolent biological behaviour, developed in the setting of a polymorphic EBV-associated lymphoproliferative disorder
Many EBV-T/NK lymphoproliferative disorder (LPD) cases clinically overlap with chronic active EBV infection which usually develops in children and young adults, it can be rarely detected in middle-aged and elderly; CAEBV diagnostic criteria are largely clinical and are represented by high viral load in peripheral blood or tissues, recurrent or persistent infectious mononucleosis-like symptoms for at least 3 months and absence of immunodeficiency [1]
Summary
Extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKL), is an uncommon subtype of lymphoma derived from NK or, less commonly, from cytotoxic T-cells, associated with Epstein-Barr virus (EBV), which usually arises in the upper aerodigestive tract [1]. It displays a peculiar geographical distribution, being extremely uncommon in Western countries with a predilection for Asian and South American populations; it is considered an aggressive form of non-Hodgkin lymphoma with a poor prognosis [1]. We report an atypical case of sinonasal NK/T-cell lymphoma with indolent biological behaviour, developed in the setting of a polymorphic EBV-associated lymphoproliferative disorder
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