Rare case of low-grade extranodal NK/T-cell lymphoma, nasal type, arising in the setting of chronic rhinosinusitis and harboring a novel N-terminal KIT mutation

Diagn Pathol. 2018 Nov 23;13(1):92. doi: 10.1186/s13000-018-0765-1.

Abstract

Background: Extranodal NK/T-cell lymphoma, nasal type (ENKTCL-NT), is a rare aggressive subtype of non-Hodgkin lymphoma characterized by angioinvasion, angiodestruction, necrosis and strong association with Epstein-Barr virus (EBV). ENKTCL-NT occurs worldwide and is more prevalent in Asian and the Native American populations of Mexico, Central and South America. It represents approximately 10% of all peripheral T-cell lymphomas worldwide. The aim of this report is to present a rare case of ENKTCL-NT with an unusually indolent clinical course and low-grade histopathologic features.

Case presentation: A 71-year-old Asian woman with a long-standing history of seasonal rhinosinusitis presented with persistent nasal congestion, cough, and fever unresponsive to antihistamines and antibiotics. Histopathological evaluation of a polypoid nasal mass revealed an atypical infiltrate with predominantly small lymphoid cells that were CD2+, surface CD3-, cytoplasmic CD3+, CD5(dim)+, CD7(dim)+, cytotoxic markers (granzyme B and perforin)+, EBER+ and CD56-. The Ki-67 proliferative index was very low (< 1%). T-cell receptor gamma gene rearrangement studies were positive for a monoclonal rearrangement, and sequencing studies identified a novel KIT mutation (p. K167 M, c. 500 A > T). A diagnosis of low-grade ENKTCL-NT was rendered.

Conclusions: Our case of ENKTCL-NT is unusual due to (1) an indolent clinical course (2) low-grade histopathologic features including a low proliferative index (3) lack of CD56 expression and (4) a novel KIT mutation. This case raises awareness of the existence of a subset of cases of ENKTCL-NT that can potentially be misdiagnosed as a reactive process, particularly in patients with recurrent chronic rhinosinusitis.

Keywords: Epstein-Barr virus; Indolent; KIT mutation; Low-grade; NK/T-cell lymphoma.

Publication types

  • Case Reports

MeSH terms

  • Aged
  • Biomarkers, Tumor / genetics*
  • Biopsy
  • Chronic Disease
  • Diagnosis, Differential
  • Female
  • Genetic Predisposition to Disease
  • Humans
  • Immunohistochemistry
  • Lymphoma, Extranodal NK-T-Cell / complications
  • Lymphoma, Extranodal NK-T-Cell / genetics*
  • Lymphoma, Extranodal NK-T-Cell / pathology
  • Lymphoma, Extranodal NK-T-Cell / surgery
  • Mutation*
  • Neoplasm Grading
  • Nose Neoplasms / complications
  • Nose Neoplasms / genetics*
  • Nose Neoplasms / pathology
  • Nose Neoplasms / surgery
  • Phenotype
  • Predictive Value of Tests
  • Proto-Oncogene Proteins c-kit / genetics*
  • Rhinitis, Allergic, Seasonal / complications*
  • Rhinitis, Allergic, Seasonal / diagnosis
  • Sinusitis / complications*
  • Sinusitis / diagnosis

Substances

  • Biomarkers, Tumor
  • KIT protein, human
  • Proto-Oncogene Proteins c-kit