The presence of CD30+ cells in cutaneous lymphomas has come to prominence in recent years as a potential diagnostic and therapeutic marker. In primary cutaneous marginal zone B-cell lymphomas, the presence of large CD30+ cells with Hodgkin-like features and their significance have not yet been studied. Here we describe the main clinical, histologic, immunophenotypic, and molecular characteristics of 13 cases of primary cutaneous marginal zone lymphomas featuring >10% of CD30+ large cells, and analyze their relationship with histologic and clinical progression of the disease and with other morphologic and immunophenotypic features. We report 10 male and 3 female patients, 4 with early-local disease and 8 with locoregional advanced disease without extracutaneous involvement but with a high relapse rate of 69%. We describe an association between a high level of CD30 expression and disease progression, with increased clinical recurrence in cases with >15% of CD30+ cells. We also discuss the differential diagnosis with other cutaneous and systemic lymphomas, especially Hodgkin lymphoma.

Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT) represents approximately 20% of cutaneous B lymphomas with an intermediate prognosis. Spontaneous regression is uncommon; there are only 2 published cases. An 83-year-old woman presented 2 orange erythematous nodules on the back of her right leg with an elastic consistency, infiltrated, painful to the touch, and of an 8-month evolution. A histological examination revealed a dense cellular dermo-hypodermic infiltrate sparing the papillary dermis, composed of large cells with immunoblast and centroblast morphology and frequent mitosis. Immunohistochemical studies showed positivity for CD20, CD79, Bcl2, Bcl6, MUM1, Fox-P1, and IgM with Ki67 >95%. Rearrangement of heavy IgH chains was monoclonal. The extension study was negative, establishing a diagnosis of PCDLBCL-LT, T2aN0M0. Three months after biopsy, the patient's lesions regressed spontaneously. New biopsies were taken that revealed a mild diffused dermo-hypodermic cellular infiltrate compounded by small-sized T lymphocytes, with predominance of CD8. Despite its self-limited character, treatment with radiotherapy was done, remaining asymptomatic after 1 year follow-up. There are 2 published cases of PCDLBCL-LT with spontaneous regression. The cause of this unusual autoinvolutional phenomenon is unknown; it may be an immune response against tumor cells through a traumatic or infectious mechanism.

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