Unifying Term Proposed for T-Cell Clonality Diseases

WAIKOLOA, HAWAII — The phrase "cutaneous T-cell lymphoid dyscrasia" could serve as a novel unifying term for a variety of chronic skin conditions characterized by persistent T-cell clonality without meeting the histologic or clinical criteria for mycosis fungoides, Dr. Joan Guitart proposed at the annual Hawaii dermatology seminar sponsored by Skin Disease Education Foundation.

Cutaneous T-cell lymphoid dyscrasias encompass eight distinct clinicopathologic precancerous entities, and is a better term than "precutaneous T-cell lymphoma" or "premycotic" because most affected patients will in fact have an innocuous, indolent clinical course without ever progressing to overt cutaneous T-cell lymphoma (Arch. Dermatol. 2007;143:921–32).

For example, long-term studies demonstrate that only 10%–15% of patients with parapsoriasis—one form of cutaneous T-cell lymphoid dyscrasia—evolve into mycosis fungoides, explained Dr. Guitart, professor of dermatology at Northwestern University, Chicago. He proposed the following criteria as requisite for cutaneous T-cell lymphoid dyscrasia:

▸ The condition is chronic with a tendency to relapse following topical therapy.

▸ There is no known triggering event, such as the occurrence of T-cell clones in conjunction with rheumatoid arthritis, lupus erythematosus, organ transplants, or other states of long-term immunostimulation. There also is no evidence of allergic reaction, hypersensitivity, or connective-tissue disorder.

▸ There is the presence of one or a few T-cell clones defined by reduced CD7 and CD62L expression in skin specimens.

▸ There is a lack of morphologic evidence for T-cell lymphoma. The dominant lymphocyte is small or intermediate in size.

Other skin disorders fitting the definition include pityriasis lichenoides chronica, idiopathic follicular mucinosis, atypical lymphocytic lobular panniculitis, clonal erythroderma, pigmented purpuric variant, syringolymphoid hyperplasia with alopecia, and hypopigmented interface variant.

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