Primary cutaneous lymphoma

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Primary cutaneous lymphomas represent a group of extranodal non-Hodgkin lymphomas (T- or B-cell) primarily confined to the skin with no evidence of extracutaneous disease at the time of diagnosis (cf. secondary involvement of the skin).

Mycosis fungoides is the most prevalent type of primary cutaneous lymphoma. Sézary syndrome, although rare, is a classic described form of T-cell cutaneous lymphoma.

Epidemiology

They account for up to a fifth of all primary extranodal forms of non-Hodgkin lymphoma .

Among the primary cutaneous lymphomas, B-cell types represent ~25% and T-cell types account for ~75% of the cases .

Clinical presentation

Skin lesions isolated to an area of the body with thickening and possible ulcerations.

B-cell lymphomas

  • up to half of the cases present with a single skin lesion
  • head and neck regions 

T-cell lymphomas

  • multiple lesions
  • trunk region 

Pathology

According to the 2018 revision of the World Health Organization–European Organization for Research and Treatment of Cancer (WHO-EORTC) classification, primary cutaneous lymphomas are divided as :

T-cell lymphomas

  • mycosis fungoides
    • variants: folliculotropic, pagetoid reticulosis, granulomatous slack skin
  • Sézary syndrome
  • adult T-cell leukemia/lymphoma
  • primary cutaneous CD30+ LPDs  
    • C-ALCL
    • LyP
  • subcutaneous panniculitis-like T-cell lymphoma
  • extranodal NK/T-cell lymphoma - nasal type
  • chronic active EBV infection
  • primary cutaneous peripheral T-cell lymphoma
    • primary cutaneous γ/δ T-cell lymphoma
    • CD8+ AECTCL (provisional)
    • primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder (provisional) 
    • primary cutaneous acral CD8+ T-cell lymphoma (provisional) 
  • primary cutaneous peripheral T-cell lymphoma, NOS 

B-cell lymphomas

  • primary cutaneous follicle center lymphoma (PCFCL)
  • primary cutaneous marginal zone B-cell lymphoma (PCMZL) 
  • primary cutaneous diffuse large B-cell lymphoma, leg type (PCLBCL)
  • EBV+ mucocutaneous ulcer (provisional)
  • intravascular large B-cell lymphoma

Radiographic features

Most of the times imaging have non-specific features and limited for staging purposes.

US and CT can demonstrate skin thickening in a nodular-like pattern or forming plaques.

Nuclear medicine

Increased avidity on 18F-FDG PET-CT is almost always present .