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Chapter 66: Cutaneous T-Cell Lymphoma (Mycosis Fungoides and Sézary Syndrome)

DEFINITION

Mycosis fungoides (and its variant Sézary syndrome)are malignant proliferations of mature memory T lymphocytes of the phenotype CD4+CD45RO+ (memory T cells). They invariably involve the skin and are the principal forms of cutaneous T-cell lymphoma.
Other types of lymphoma may also have prominent skin involvement (see Table 66–1).

TABLE 66–1WORLD HEALTH ORGANIZATION–EUROPEAN ORGANIZATION FOR RESEARCH AND TREATMENT OF CANCER CLASSIFICATION OF PRIMARY CUTANEOUS T-CELL AND NATURAL KILLER CELL LYMPHOMAS

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TABLE 66–1 WORLD HEALTH ORGANIZATION–EUROPEAN ORGANIZATION FOR RESEARCH AND TREATMENT OF CANCER CLASSIFICATION OF PRIMARY CUTANEOUS T-CELL AND NATURAL KILLER CELL LYMPHOMAS

Mycosis Fungoides
1. Mycosis fungoides variants and subtypes
  1. Folliculotropic mycosis fungoides
  2. Pagetoid reticulosis
  3. Granulomatous slack skin
Sézary Syndrome
Adult T-Cell Leukemia/Lymphoma
Primary Cutaneous CD30+ Lymphoproliferative Disorders
1. Primary cutaneous anaplastic large cell lymphoma
2. Lymphomatoid papulosis
Subcutaneous Panniculitis-Like T-Cell Lymphoma
Extranodal Natural Killer/T-Cell Lymphoma, Nasal Type
Primary Cutaneous Peripheral T-Cell Lymphoma, Unspecified
1. Primary cutaneous aggressive epidermotropic CD8+ T-cell lymphoma (provisional)
2. Cutaneous γδT-cell lymphoma (provisional)
3. Primary cutaneous CD4+ small/medium-sized pleomorphic T-cell lymphoma (provisional)
Precursor Hematologic Neoplasm
1. CD4+/CD56+ hematodermic neoplasm (blastic NK-cell lymphoma)

Source: Williams Hematology, 8th ed, Chap. 105, Table 105–1, p. 1596.

EPIDEMIOLOGY

Cutaneous T-cell lymphoma are two-fold more common in males than females.
Median age at diagnosis is 55 years.
In the United States, there are approximately 1000 cases per year representing about 1.5 percent of lymphomas.

CLINICAL FINDINGS

Patients usually present with nonspecific skin lesions (chronic dermatitis) occurring years before diagnosis.
Early in disease, patients are often diagnosed with eczema (spongiotic dermatitis), psoriatic-like dermatitis, or other nonspecific dermatoses associated with pruritus.
Histologic diagnosis may be difficult in early stages. Neoplastic infiltrates may be minimal, masked by normal inflammatory cells, and the neoplastic mature CD4+ phenotype may be misinterpreted as normal inflammatory cells.
Mycosis fungoides may be divided into patch stage (patch-only disease), plaque stage (both patches and plaques) and tumor stage (more than one tumor along with patches and plaques).
A patch is defined as a flat lesion with varying degrees of erythema with fine scaling; a plaque is defined as a demarcated, erythematous, brownish lesion, with variable scaling of at least 1 mm elevation above the skin surface; a tumor extends at least 5 mm above the surface (tumors are usually in a setting of patches and plaques) (see Fig. 66–1).
Mycosis fungoides d'emblée is an aggressive form with a poor prognosis characterized by tumors arising de novo in the absence of patches or plaques.
Lesions have a predisposition for skin folds and non–sun exposed areas (bathing-trunk distribution) but in later stages they can be generalized and involve the face, palms, soles, and other areas.
Progression through stages usually occurs over years but some cases may present with late stage lesions.
Pruritus may be mild or severe and is one of the principal quality of life issues for patients. It ...