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).

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 ...