CD56+ lymphoma with skin involvement: clinicopathologic features and classification.

Background: Extranodal lymphomas expressing CD56 (neuronal cell adhesion molecule) are characterized by a high incidence of cutaneous involvement and a very aggressive clinical course. Knowledge about the prognosis and clinicopathologic features of CD56(+) lymphomas with skin involvement is very limited.
Objectives: To determine survival and prognostic factors for extranodal CD56(+) lymphomas with skin involvement and to describe their clinicopathologic features.
Design: Retrospective literature survey and case studies.
Patients: A total of 181 patients with CD56(+) lymphoma involving the skin: 177 cases from the literature and 4 new cases.
Main Outcome Measure: Survival and its dependence on the following putative prognostic factors: staging, histopathologic findings, lymphocyte markers, T-cell receptor gene rearrangement, Epstein-Barr virus infection, treatment modality.
Results: Three major subtypes of CD56(+) lymphoma in the skin were distinguished: blastic lymphoma, nasal-type natural killer-cell/T-cell lymphoma, and subcutaneous panniculitislike lymphoma. The disease disseminated readily, mainly to lymph nodes, bone marrow, the central nervous system, and the liver, but 45% of patients had a purely cutaneous disease at presentation. All subtypes had a very aggressive course with a median survival of 14 months. The main risk factors were age older than 55 years (hazard ratio [HR], 2.5; 95% confidence interval [CI], 1.8-3.2), systemic dissemination at presentation (HR, 2.0; 95% CI, 1.5-3.3), and lack of CD30 (HR, 3.8; 95% CI, 1.4-4.9) or CD4 expression (HR, 1.56; 95% CI, 1.06-2.57). The different treatment modalities did not improve survival.
Conclusions: CD56(+) lymphomas involving the skin are rare and extremely aggressive regardless of their histologic presentation and the extent of skin involvement. No effective treatment is available. The risk of death is particularly increased in older patients with CD30(-)CD4(-) lymphomas.