Lymphomatoid Papulosis (LyP)
Epidemiology:
- Adults (45y. median)
- Children maybe
- M>F (2-3:1)
- Lymphoma association:
- Preceded by
- Associated with
- Followed by
- Types:
§ MF
§ Cutaneous ALCL
§ Hodgkin
Common sites:
- Skin-limited
- Oral mucosa (rarely)
Gross features:
- variable
- may look identical to PLEVA
- may have large ulcerated plaques and nodules
- papular maybe
- papulonecrotic maybe
- nodular maybe
- spontaneously regressing
- may leave behind superficial scars
Histologic features:
- extremely variable
- correlates with the age of the lesion
- large, atypical, anaplastic, immunoblastic
or Hodgin-like cells
- hyperchromatic, convoluted, bizarre-shaped nuclei
- “lumps of coal”
- most prevalent in papillary and upper reticular
dermis
- marked inflammatory background
- Histiocytes
- Small lymphocytes
- Neutrophils
- eosinophils
- 3 histologic types representing a spectrum:
- Type A
- Scattered or small clusters
- Large, sometimes multinucleated or R-S-like
CD30+ T-cells
- Numerous inflammatory cells intermingled
- Type B (< 10%)
- Epidermotropic infiltrate of small atypical cells with cerbriform
nuclei similar to MF
- Type C
- Monotonous population or large clusters
- Large CD30+ T-cells
- Relatively few admixed inflammatory cells
- may resemble PLEVA or PLC
or MF (type B)
Immunophenotype:
- Type A and Type C:
- Large cells have the same immunophenotype
as C-ALCL
- Type B:
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Marker:
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Sensitivity:
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Specificity:
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(Type B) :
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CD3
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CD4
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CD8 (neg)
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Rare cases are
positive with an NK-cell phenotype
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CD30 (neg)
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Molecular features:
- TCR gene rearrangement (60%)
- Identical to associated lymphomas
- No consistent abnormalities
- NOT t(2;5)(p23;q35)
Other features:
- Chronic
- Several months to 40 years
- Recurrent
- Self-healing
- Individual skin lesions disappear within 3-12
weeks
- Excellent prognosis (2% mortality in 77 months)
- A small but significant percentage eventually
develop into cutaneous or nodal lymphoma
References: