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T-cell Neoplasia
T-cell neoplasias commonly involve the skin. One category - in which, for long intervals, there are opportunities for neoplastic progressions - is primarily restricted to the skin. The latter category was formerly
given recognition as “mycosis fungoides” (MF). The latter designation has retained some usefulness, but has been criticized as lacking in specificity; it was too easy to include lymphomas of non-skin origin in the
category. In addition, there were problems in making a distinction between early mycosis fungoides and “parapsoriasis” (always with questions as to whether such a distinction would be legitimate). With the advent of
cell markers, the archaic terminology as been replaced by one in which emphasis is placed on the type of lymphoid cell (i.e., T-cell); the respective primary neoplasm of the skin has thus become a primary cutaneous
T-cell lymphoma (CTCL). In spite of the advances in the specificity of the terminology, the new designation is as much abused as, or more abused than, the archaic designation. It is to the advantage of clinicians to
have great leeway in defining the “intensions” of the designation, CTCL.
The infiltrates of the classic primary, progressive T-cell neoplasia of the skin are, in early stages, confined to the epidermis and the adventitial dermis (the papillary dermis and the perifollicular connective
sheaths). This confinement might be characterized as an expression of the same respect for a native domain as that exhibited by non-neoplastic T cells in certain inflammatory processes. Since the so-called
“interstitial” variant of MF does not exhibit this type of respect, it seems to be improper to include it as a variant of MF.
For as long as the infiltrates of a T-cell neoplasm respect the domain of the reactive superficial unit (epidermis and adventitial dermis) and, in addition, for as long as they are composed of small cells showing
only mild, or even moderate cytologic atypia, then it might be proper to characterize such patterns as a cutaneous T-cell dysplasia, rather than lymphoma.
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