Clinicopathological analysis of primary central nervous system NK/T cell lymphoma: rare and localized aggressive tumour among extranasal NK/T cell tumours.
OBJECTIVE
The central nervous system (CNS) is a rare primary site of non-Hodgkin lymphoma. Although direct invasion of nasal natural killer (NK)/T cell tumours into CNS is reported occasionally, primary CNS NK/T cell lymphoma is extremely rare, and the clinicopathological features of primary CNS NK/T cell lymphoma remain largely unknown.


RESULTS
We identified four cases from our consultation files and analysed the clinicopathological features. Three were immunocompetent and one was immunosuppressed. There were three males and one female and their ages ranged from 21 to 77 years (median: 46 years). Radiotherapy was rendered for all patients, and methotrexate was administered to two patients. The overall survival was 4-29 months (median, 19 months) for the three immunocompetent patients. Neoplastic cells exhibited medium to large atypical nuclei. Angiocentric growth and necrosis were observed. The immunophenotype was typical of NK cell tumours: CD3ε, 100%; CD56, 67%; CD5, 50%; cytotoxic molecules, 100%; Epstein-Barr virus encoded small RNA (EBER), 100% and T cell receptor (TCR)-β or γ, 0%. No TCR-gene rearrangements were detected. Reviewing 10 additional cases from the literature and comparing with extranasal NK/T cell lymphoma of the more frequent origins (skin or gastrointestinal tract), primary CNS NK/T cell lymphoma was diagnosed at an earlier stage without B symptoms but exhibited aggressive clinical behaviours.


CONCLUSIONS
Although extremely rare, primary CNS NK/T cell lymphoma does occur and should always be included in the differential diagnosis and we should apply relevant markers routinely in conjunction with exploring the patient background. The accumulation of cases is indispensable to establish an effective treatment strategy for this rare and aggressive malignancy.
Department of Pathology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
Tomoko
T
Miyata-Takata
Department of Pathology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
Katsuyoshi
http://orcid.org/0000-0001-6890-1276
K
Takata
Department of Pathology and Laboratory Medicine, Nagoya University Hospital, Nagoya, Japan.
Seiichi
http://orcid.org/0000-0001-9713-3691
S
Kato
Department of Pathology and Laboratory Medicine, Nagoya University Hospital, Nagoya, Japan.|Department of Gastroenterology and Hepatology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Lei-Ming
LM
Hu
Department of Pathology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
Mai
M
Noujima-Harada
Department of Pathology, Chi-Mei Medical Center, Tainan, Taiwan.
Shih-Sung
SS
Chuang
Department of Pathology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
Yasuharu
http://orcid.org/0000-0001-5234-6861
Y
Sato
Department of Hematology and Oncology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
Yoshinobu
Y
Maeda
Department of Pathology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
Tadashi
T
Yoshino
D000328:Adult; D000368:Aged; D016543:Central Nervous System Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D054391:Lymphoma, Extranodal NK-T-Cell / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D055815:Young Adult
Epstein-Barr virus; central nervous system; extranodal NK/T cell lymphoma