Most primary cutaneous CD30-positive lymphoproliferative disorders have a CD4-positive cytotoxic T-cell phenotype.

Primary cutaneous CD30-positive (anaplastic) large T-cell lymphomas and lymphomatoid papulosis are closely related types of cutaneous T-cell lymphoma with a favorable prognosis. The neoplastic T cells in these conditions have the phenotype of activated CD3+, CD4+, CD8-, CD30+ skin homing T cells, but their normal counterpart has not yet been defined. To further characterize the cellular origin of the neoplastic T cells, skin biopsies from 14 patients with primary cutaneous CD30-positive (anaplastic) large T-cell lymphomas, nine patients with lymphomatoid papulosis, and six patients with primary cutaneous CD30-negative pleomorphic large T-cell lymphomas were stained with monoclonal antibodies against cytotoxic cell-associated molecules granzyme B and T-cell restricted intracellular antigen. In nine of nine lymphomatoid papulosis and in 10 of 14 CD30-positive primary cutaneous large T-cell lymphomas, expression of granzyme B and T-cell restricted intracellular antigen by variable numbers of neoplastic cells was found. Expression of granzyme B by the neoplastic CD30-positive T cells was confirmed by double-staining for granzyme B and CD30 (three cases) and by the detection of granzyme B mRNA using RNA in situ hybridization (one case). In most cases equal numbers of granzyme-B-positive and T-cell restricted intracellular antigen positive tumor cells were observed. In five of six CD30-negative primary cutaneous large T-cell lymphomas the neoplastic cells did not express these proteins, whereas in one case a sporadic positive tumor cell was found. These results demonstrate that, in contrast to primary cutaneous CD30-negative pleomorphic large T-cell lymphomas, the neoplastic cells in most primary cutaneous CD30-positive (anaplastic) large T-cell lymphomas and lymphomatoid papulosis have a unique CD4+, CD8-, cytotoxic T-cell phenotype.