Cutaneous Lymphomas

Question 1

T-cell clones found in what reactive conditions?

Answer 1

• PLEVA
• PLC
• Drug reactions
• others

Question 2

Mycosis Fungoides

Clinical

Histo

DDX

IPOX

Answer 2

Clinical

• long-history
• sun-protected sites initially

Histo:

• epidermotropism
• linear array along basal epidermis (without spong)
• Pautrier’s microabscesses
• Plaques have psoriasiform or lichenoid pattern
• Tumor stage shows large, highly atypical cells with large cell transformation, CD30+

DDX:

• Spongiotic dermatitis (> spong and < exocytosis; eosinophils, vesicles, Langerhans cells)

IPOX

Positive: CD3, CD4

Negative: CD30, CD8 (unless aggressive CD8 epidermotropic CTCL or gamma-delta lymphoma)

Loss of CD5 and CD7

Question 3

CD30+ lymphoproliferative disorders of the skin

Answer 3

1. Lymphomatoid papulosis
   
   • Types A, B, C
   • Multiple regressing papules
   • A - CD30+ cells mimic RS cells
   • B - looks like MF
   • C - looks like ALCL
2. ALCL
   
   • one nodule
   • sheets of large, atypical CD4+, CD30+ and EMA and ALK negative lymphs
   • EMA and ALK can r/o systemic ALK

Question 4

Most common cutaneous B-cell lymphoma

Answer 4

Marginal zone

CLinical: one to few papules or nodules (possibly for years)

Histo: monocytoid B-cells; often plasmacytic diff’n at periphery

IPOX:

Positive: CD20, CD79a, bcl-2

Negative: bcl-6, CD5, CD10

+/- CD43

low ki-67

kappa or lambda restricted

Question 5

Cutaneous follicular lymphoma

Answer 5

Clinical: one to few reddish/brown nodules on head and neck or upper trunk

Histo: follicular to diffuse, follicles lack mantle zones; centrocytes; lacks plasma cells

IPOX:

Positive: CD20, CD79a, CD10, bcl-6

Negative: CD5

+/- bcl-2

low ki-67