Clinical Features:

• Indolent cutaneous T-cell lymphoma with a peak incidence in the fifth to seventh decades
• Gradual progression over a number of years through three clinical stages: patch, plaque and tumor
• If there is leukemic involvement, the term Sézary syndrome is used.

Histologic Features:

• Patch stage:
  • Usually scant perivascular, band-like or periadnexal infiltrate of small lymphocytes, often with atypia (described as "cerebriform")
  • Epidermotropism (tumor cells found within the epidermis): single cells and sometimes small collections
  • Haloes around the intraepidermal lymphocytes may be present.
  • Sometimes fibroplasia of the papillary dermis ("wiry collagen")
  • Superficial dermal edema and vascular proliferation may be present.
  • Absent to minimal spongiosis (helpful in the differential diagnosis with eczematous disorders, which may be indistinguishable from MF at this stage)

• Plaque stage:
  • Dense band-like subepidermal infiltrate of neoplastic lymphocytes
  • More significant epidermotropism with occasional Pautrier microabscesses (punched-out spaces within the epidermis filled with neoplastic lymphocytes)

• Tumor stage:
  • Dense, nodular proliferation of tumor cells filling the upper dermis and extending deeper than in earlier stages
  • There is often a significant decrease or loss of epidermotropism.
  • The lymphocytes acquire a more significant degree of atypia, with nuclear enlargement, greater irregularity of the nuclear contour and hyperchromia.

• Immunophenotype: CD4+ (helper) T-cells (positive for CD2, CD3, CD5, CD7, CD45RO).
• Loss of one or more pan-T-cell marker may occur and is supportive evidence for a neoplastic process.

Cases associated with this book:

Mycosis fungoides
Author: Artur Zembowicz M.D. Ph.D.

Conference: DermatopathologyConsultations.com Teaching Collection