Author(s)

Valentina Tabanelli¹, Riccardo Valli², Magda Zanelli², Simona Righi¹, Anna Gazzola¹, Claudia Mannu¹, Stefano Pileri¹, Elena Sabattini¹

¹Hematopathology and Haematology Sections, Department of Experimental, Diagnostic and Specialty Medicine, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy.
²Anatomic Pathology Unit, IRCSS Santa Maria Nuova Hospital, Reggio Emilia, Italy.

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.

ENKL, Indolent, CAEBV, EBV

Tabanelli, V. , Valli, R. , Zanelli, M. , Righi, S. , Gazzola, A. , Mannu, C. , Pileri, S. and Sabattini, E. (2014) A Case of Sinonasal Extranodal NK/T-Cell Lymphoma with Indolent Behaviour and Low-Grade Morphology. Case Reports in Clinical Medicine, 3, 596-600. doi: 10.4236/crcm.2014.311129.