Extra-nasal NK/T cell lymphoma masquerading as renal infarction

Abstract

Extra-nodal nasal or nasal-type natural killer (NK)/T cell lymphoma is a very rare and aggressive lymphoma that is usually found in Asian and Hispanic communities. Extra-nasal presentation (nasal-type NK/T cell lymphoma), possibly with the exception of cutaneous involvement, portends a particularly poor prognosis, with poor response to treatment. Definitive diagnosis is often delayed due to atypical presentation. We report here a case of a patient with an atypical presentation of nasal-type NK/T cell lymphoma in the kidney, who initially achieved complete remission post radical nephrectomy and involved field radiotherapy, but relapsed 3 months later and died 12 months from the onset of disease. A 72-year-old Caucasian male with a previous abdominal aortic aneurysm repair presented with left flank pain. Initial abdominal computed tomography (CT) demonstrated extensive heterogeneous soft tissue surrounding the abdominal aorta at the level of the renal artery, and replacement of the lower pole of the left kidney with a heterogeneous low-density mass (Figure 1). Subsequent correlative ultrasonography revealed a vascular left lower pole renal mass, which was reported as consistent with a renal cell carcinoma. A left radical nephrectomy was performed; histology unexpectedly showed diffuse patchy lymphoid infiltrates with solid areas of large atypical lymphocytes which were CD3þ, CD47, CD8þ ,C D2þ, CD7þ, and CD56þ, and CD207. Granzyme showed granular positivity and perforin was negative. Ki67 was 60%þ in the large cell areas. EBER-ISH (Epstein‐Barr virus-encoded RNA in situ hybridization) was positive (Figure 2). There was no evidence of angioinvasion and necrosis in the excised tissue. These features were consistent with extranasal NK/T cell lymphoma. Serologically, the patient was positive for Epstein‐Barr virus (EBV) immunoglobulin G (IgG) and negative for EBV IgM. Serum EBV DNA was detectable, but a viral load was not obtained. There was a high b2-microglobulin level of 4.8 mg/L. The serum lactate dehydrogenase (LDH) level was 226 U/L. Bone marrow aspiration and trephine showed no evidence of lymphoma. Further staging with CT and positron emission tomography (PET) showed no evidence of fluorodeoxyglucose (FDG)-avid disease elsewhere. The areas of soft tissue thickening around the abdominal aorta were in keeping with aortitis with focal inflammation rather than definite nodal disease. The patient proceeded to involved field irradiation with 30 Gy, without chemotherapy, and achieved complete metabolic remission for a total of 3 months. A repeat PET scan unfortunately demonstrated relapsed intra-abdominal lymphadenopathy. The patient was unable to tolerate subsequent radiotherapy due to significant back pain, and therefore elected to receive palliative care thereafter; consequently, the patient died 12 months after the initial diagnosis was made. Extra-nodal NK/T cell lymphoma is a rare form of lymphoma that can be subcategorized into nasal or nasal-type NK/T cell lymphoma. The former typically presents as a midline facial destructive lesion, typically within the nasal cavity, whereas extra-nasal