Mature T/NK-Cell lymphomas of the oral and maxillofacial region: A multi-institutional collaborative study.

Background The diagnosis of oral and maxillofacial mature T/NK-cell neoplasms is challenging because of their rarity, morphological heterogeneity and complex immunophenotype, with scarce available data describing their clinical and microscopic aspects. Therefore, in this study we investigated a series of mature T/NK-cell neoplasms affecting this anatomical region and provided an updated literature review. Methods Cases diagnosed as mature T/NK cell lymphomas affecting the oral and maxillofacial region were retrospectively retrieved from six pathology files and their diagnoses were confirmed using haematoxylin and eosin-stained slides, immunohistochemical reactions and in situ hybridization for Epstein-Barr virus (EBV) detection. Patients' clinical data were collected from their pathology forms. Results A total of 22 cases were included in this study. Eleven (50%) consisted of extranodal NK/T-cell lymphomas, nasal type; eight (36.4%) were peripheral T-cell lymphomas, NOS; two (9.1%) were adult T-cell leukaemia/lymphomas, and one (4.5%) was an ALK-positive anaplastic large cell lymphoma. Overall, males predominated, with a mean age of 55.7 years. The palate was the most affected site (50%), and tumours usually presented as destructive and painful ulcers. EBV was present in all cases of extranodal NK/T cell lymphoma nasal type, but was absent in the other subtypes. Conclusion Among mature T/NK-cell lymphomas of the oral and maxillofacial region, extranodal NK/T cell lymphoma, nasal type and peripheral T-cell lymphoma, NOS predominated. Older men were the most affected patients, and this heterogenous group of neoplasms has a very aggressive clinical behaviour.