Secondary cutaneous involvement by direct extension in high-grade B-cell lymphomas.

Cutaneous involvement by a systemic lymphoma via direct extension is a very rare phenomenon, historically described in patients who had advanced-stage disease with bulky lymphadenopathy. Since its original description, most cases of cutaneous lymphomatous spread via direct extension are attributable to Hodgkin disease. Here, we report the occurrence of direct cutaneous dissemination in the setting of nodal high-grade B-cell lymphomas, specifically diffuse large B-cell lymphoma (DLBCL) and B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and classical Hodgkin lymphoma (also called gray-zone lymphoma). Both cases are adequately documented with clinical, histopathologic, and immunophenotypic data, as well as additional cytogenetic analysis.