Primary Cutaneous Anaplastic Large Cell Lymphoma (C-ALCL)

 

Epidemiology and Etiology:

    • Adults / elderly

 

Common sites:

    • Limited to Skin at diagnosis (nearly all)
    • Extracutaneous dissemination may occur (10%)
      • Lymph nodes
    • Other organ involvement is rare

 

Gross features:

    • Solitary or localized skin lesions
      • Tumours
      • Nodules
      • Papules (rare)
    • Multicentric (20%)

 

Histologic features:

    • Diffuse infiltrate
      • Involving both upper and deep dermis and subcutaneous tissue
      • Epidermal invasion and ulceration may be seen but epidermotropism is less common
      • Modest inflammatory background maybe
        • An abundant inflammatory background suggests lymphomatoid papulosis
    • Cytologic features similar to systemic ALCL
      • However pleomorphic, multinucleated giant cells and Reed-Sternberg-like cells are often more numerous
        • Resemble cells in Type A lesions of lymphomatoid papulosis
        •  

 

Immunophenotype:

Marker:

Sensitivity:

Specificity:

CD30 (>75% of cells)

 By definition

 

T cell markers, commonly with variable loss of CD2, CD5, and/or CD3

 

 

CD4

Usually

 

Cytotoxic markers:

Granzyme B, perforin, TIA-1

70%

 

HECA-452

50%

 

EMA (neg)

 

 

ALK (neg)

 

 

Cutaneous lymphocyte antigen

 

 

 

Molecular features:

    • clonally rearranged TCR genes
    • NPM-ALK fusion transcripts (small minority – may be cutaneous involvement with systemic ALCL)
    • NOT t(2;5)

 

Other features:

    • limited to the skin at presentation (nearly all)
    • may spontaneously regress, similar to lymphomatoid papulosis
      • cutaneous relapses are frequent

 

References:

    • WHO blue book (2001)