%0 Journal Article %J Ophthalmic Plast Reconstr Surg %D 2019 %T Orbital Nasal-Type Extranodal Natural Killer/T-Cell Lymphoma: An Ongoing Diagnostic Challenge Further Confounded by Small-Cell Predominance %A Wolkow, Natalie %A Jakobiec, Frederick A %A Habib, Larissa A %A Freitag, Suzanne K %X PURPOSE: To highlight the histopathologic diagnostic challenges of small-cell predominant extranodal nasal-type natural killer/T-cell lymphoma (ENTNKT) of the orbit. METHODS: Retrospective chart review and histopathologic study with immunohistochemistry and in situ hybridization of 3 cases. RESULTS: Three cases of ENTNKT presented to the Mass Eye and Ear emergency room as orbital cellulitis over 1 year. The first case was unusual in that there was a predominance of small cells, giving the ENTNKT the histopathologic appearance of a nonmalignant inflammatory process. This challenging case is juxtaposed alongside 2 other cases, which exhibited the more typical lymphomatous microscopic appearance. DISCUSSION: ENTNKT can extend into the orbit from the adjacent sinuses or rarely arise primarily in the orbit. A diagnosis is typically made with a biopsy. Occasionally, however, the histopathologic diagnosis can be elusive when a predominance of small lymphomatous cells that are virtually indistinguishable from non-neoplastic inflammatory cells is present. Demonstration of CD56 positivity by immunostaining and in situ hybridization for Epstein-Barr virus are essential in confirming the diagnosis. CONCLUSIONS: ENTNKT should be considered both in the clinical and histopathologic differential diagnoses of orbital infections and idiopathic inflammations (pseudotumor). %B Ophthalmic Plast Reconstr Surg %V 35 %P 478-483 %8 2019 Sep/Oct %G eng %N 5 %1 http://www.ncbi.nlm.nih.gov/pubmed/30865070?dopt=Abstract %R 10.1097/IOP.0000000000001333