Primary adrenal CD56-negative extranodal NK/T-cell lymphoma: Case report and literature review.

Primary adrenal extranodal natural killer (NK)/T-cell lymphoma (ENKTL) is exceptionally rare, and it remains unclear whether this subtype of ENKTL exhibits distinct clinicopathological features. This case report describes a later 30s female patient who presented with 6 months of back pain. 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) revealed a hypermetabolic left adrenal mass. Histopathology revealed diffuse atypical lymphocytes with necrosis and vascular invasion. Immunohistochemical analysis demonstrated tumor cell positivity for CD3, CD2, CD8, TIA-1, and granzyme B, while being negative for CD5, CD4, CD56, CD20, Pax-5, CD30 and keratin, with a Ki-67 proliferation index of approximately 80%. Chromogenic in situ hybridization showed strong and uniform nuclear positivity of Epstein-Barr virus-encoded RNA (EBER) in the neoplastic population. T-cell receptor rearrangement (TR-γ) was in germline configuration. The final diagnosis of primary adrenal CD56-negative extranodal NK/T-cell lymphoma was confirmed. Chemotherapy was initiated immediately. But she died within 4 months because of disease progression. Primary adrenal ENKTL appears to be exceedingly rare and might portend a particularly poor prognosis. CD56 negativity and advanced stage could potentially represent key prognostic determinants.