Neurosurgery notes/Tumours/Haematolymphoid and histiocytic tumours/Lymphomas/T-cell and NK/T-cell lymphomas/NK/T-cell Lymphoma (Nasal Type)

NK/T-cell Lymphoma (Nasal Type)

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T-cell and NK/T-cell lymphomas

Definition

  • Essential
    • Biopsy-proven lymphoma manifesting in the CNS.
    • NK-cell immunophenotype (typically CD3+, CD2+, CD5-, CD7+, CD56+) OR Cytotoxic T-cell immunophenotype (typically CD3+, CD8+).
  • Desirable
    • Expression of cytotoxic molecules (perforin, granzyme B).
    • Absence of clonal TR gene rearrangement in cases of NK-cell lineage.

Numbers

  • Adults (median age: fifth decade, range 21–77 years)
  • Male preponderance (M:F ratio of approximately 2:1).
  • Most reported cases have involved Asian patients.

Localisation

  • Primarily manifests in the CNS
  • Usually forming a single mass, although multiple lesions can occur.
  • Involved sites typically include the frontal and temporal lobes, pituitary, and cerebellum.

Clinical Features

  • Symptoms are often rapidly progressive, including dizziness, headache, vomiting, paralysis, weakness, aphasia, dysphagia, dysarthria, and mental deterioration. The manifestations may mimic a cerebrovascular accident.

Histopathology and Immunophenotype

Macroscopic

  • Necrosis is common.

Microscopic Features

  • The tumour consists of atypical lymphoid cells that range from medium-sized to large, often exhibiting pleomorphic features and irregular nuclei.
  • A key finding is angiocentric growth accompanied by extensive necrosis, which is typically coagulative. Mitotic figures are readily found.

Immunophenotype

  • Neoplastic cells are usually positive for CD3, CD56, cytotoxic granule protein, and EBV-encoded small RNA (EBER).
  • They are typically negative for CD5 and B-cell antigens.

Pathogenesis

  • The rearrangement of TR genes is usually in germline configuration, though clonal rearrangement may occur.
  • In a subset of patients, immunodeficiency (such as HIV infection or prior transplantation) may play a role in the aetiology.

Management

  • Methotrexate-based chemotherapy may offer a benefit.

Prognosis

  • The prognosis is generally poor, with the disease progressing rapidly.
    • Poor prognostic subtype
      • EBV-positive nasal-type extranodal NK/T-cell lymphoma primary to the CNS
        • Mainly affects young to middle-aged adult men
        • Has pathological features similar to those seen in other sites, and
        • Very poor prognosis
  • Median survival is short, approximately 6 months (range 1–18 months), and long-term survival is rare.