Extranodal NK
/ T-cell Lymphoma, Nasal Type
Nasal NK lymphoma
Epidemiology and
Etiology:
- EBV+
(almost all)
- Most
are activated NK cell origin
- Rare
cases are cytotoxic T cell phenotype
- Endemic
places:
- Asia,
Mexico, Central and South America
- Adults
most often
- M >
F
- Immunosuppressed
/ post-transplant in some
Common sites:
- nasal
cavity is commonest and prototypic
- other
extranodal sites:
- palate
- skin
- soft
tissue
- GI
tract
- Testis
- Secondary
lymph node involvement in some
- Bone
marrow very uncommon
Gross features:
- Prominent
necrosis
- ulceration
- Skin
nodules, often ulcerated
Histologic features:
- May
mimic an inflammatory process
- Diffuse
infiltrate, often angiocentric, with vascular destruction
- Medium-sized
lymphocytes usually
- Broad
cytologic spectrum – cells may be small, medium, large, or anaplastic,
or mixture of small and large
- Irregular
nuclei – may be elongated
- Granular
chromatin
- May
be vesicular in larger cells
- Inconspicuous
nucleoli
- Moderate
cytoplasm, pale to clear
- Azurophilic
granules seen in Giemsa stain
- Frequent
mitoses
- apoptotic
bodies frequent
- Heavy
admixture of inflammatory cells often:
- Small
lymphocytes
- Plasma
cells
- Histiocytes
- eosinophils
- angiodestructive
- Fibrinous changes in the blood
vessels maybe
- extensive
ulceration
- prominent
necrosis
- coagulative
necrosis
- angiocentric
- florid
pseudoepitheliomatous hyperplasia sometimes
Immunophenotype
& Special stains:
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Marker:
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Sensitivity:
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Specificity:
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EBER
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Almost all
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CD2
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CD56
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May be negative
if EBV+ and cytotoxic proteins +
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CD43
|
Commonly
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CD3
(cytoplasmic, not membranous)
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Granzymes B
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TIA-1
|
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Perforin
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CD4 (neg)
|
May be positive
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CD5 (neg)
|
Typically
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CD7 (neg)
|
Typically
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CD 8 (neg)
|
May be positive
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TCR-Beta (neg)
|
Typically
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TCR-Gamma (neg)
|
Typically
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CD16 (neg)
|
Typically
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CD57 (neg)
|
Typically
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CD45
|
Commonly
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CD7
|
Occasional
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CD30
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Occasional
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TdT (neg)
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CD25 (neg)
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Molecular features:
- no
rearranged TCR or Ig genes (usually)
- EBV
(great majority)
- Del(6)(q21q25)
or I(6)(p10) amongst others
Other features:
- EM – electron
dense granules
- clinical
features:
- nasal
obstruction
- epistaxis
- extensive
midfacial destructive lesions (lethal midline granuloma)
- hemophagocytic
syndrome in some
- perforation
in GI lesions
- variable
response to therapy, variable prognosis
- occurring
outside the nasal cavity is highly aggressive with short survival times
References: