Classification of primary cutaneous large cell lymphomas.

Primary cutaneous large cell lymphomas represent a heterogeneous group of malignant lymphomas of T- and B-cell origin. Recent studies have been successful in delineating some well-defined clinicopathologic entities within this group. Primary cutaneous follicular (germinal) center cell lymphomas are the most common type of CBCL. These lymphomas generally present with localized skin lesions on the trunk or scalp. They have an indolent clinical course, are highly sensitive to radiotherapy, and have a favorable prognosis. Within the group of primary cutaneous T-LCL, distinction primarily should be made between CD30-positive (> 75% or large clusters of tumor cells) and CD30-negative (no or few scattered positive cells) T-LCL. Primary cutaneous CD30-positive T-LCL, which includes both anaplastic and non-anaplastic subtypes, have recently been defined as a distinct clinicopathologic entity with a favorable prognosis. The overlapping clinical and histological features with LyP suggest that both conditions are part of a broader spectrum of primary cutaneous CD30-positive lymphoproliferative disorders. Primary CD30-negative T-LCL generally are associated with a poor prognosis (4-year-survival, < 25%). Reports on this group are still few, however, and further studies are required to define subgroups with a more favorable prognosis within this heterogeneous group of lymphomas.

Demonstration of clonal immunoglobulin gene rearrangements in cutaneous B-cell lymphomas and pseudo-B-cell lymphomas: differential diagnostic and pathogenetic aspects.

Twenty-five patients with a benign or malignant cutaneous B-cell lymphoproliferative disease, including seven cutaneous pseudo-B-cell lymphomas, eight primary cutaneous B-cell lymphomas (CBCL), and 10 secondary cutaneous B-cell lymphomas, were investigated for the presence of clonal immunoglobulin (Ig) gene rearrangements using Southern blot hybridization analysis. The selection of pseudo-B-cell lymphomas was based on the presence of polyclonal light-chain expression with immunohistochemical analysis. All cases of CBCL demonstrated monotypic light-chain expression or absence of detectable Ig on CD20+ B cells. Clonal rearrangements of one or more Ig genes were demonstrated in four of seven cases of cutaneous pseudo-B-cell lymphomas, six of eight cases of primary CBCL, and in all cases of secondary CBCL. The observation that cutaneous pseudo-B-cell lymphomas as defined by immunohistochemical criteria often contain occult monoclonal B-cell populations implies that differentiating between pseudo-B-cell lymphomas and CBCL is not always possible by means of gene-rearrangement analysis. These findings may support the concept that cutaneous pseudo-B-cell lymphomas and primary CBCL are part of a continuous and progressive spectrum of B-cell lymphoproliferative skin disorders.

Mycosis fungoides-like lesions associated with phenytoin and carbamazepine therapy.

We report the cases of four patients who were taking the anticonvulsant drugs phenytoin or carbamazepine and in whom skin lesions developed that showed histologic features suggestive of mycosis fungoides. Two patients had a solitary lesion on the trunk, whereas the other two patients had multiple plaques. In all four patients systemic signs were absent.

Direct macrophage migration inhibition test in DNCB contact sensitized guinea pigs.

Using dinitrochlorbenzene contact-sensitized guinea pigs, several DNP conjugates have been assayed in the direct macrophage migration inhibition test (MMIT). Although no significant differences could be observed between the carriers used, conjugates prepared from serum proteins and epidermal extracts tended to give the strongest inhibition of macrophage migration. Conjugates prepared from cells cultured in vitro in the presence of hapten did not cause more inhibition than control conjugates prepared in the absence of cell metabolism. The direct MMIT showed statistical differences between sensitized and nonsensitized groups of guinea pigs. However, none of the conjugates permitted conclusions to be drawn with regard to individual animals.