[493] Clinicopathologic Spectrum of Cutaneous Marginal Zone Lymphoma: Differences between Primary and Secondary Involvement

Adriana Garcia-Herrera, Alejandra Carvajal-Cuenca, Dolors Colomer, Lluis Colomo, Antonio Martinez, Teresa Estrach, Elias Campo. Hospital Clinic, Barcelona, Spain

Background: Cutaneous marginal zone lymphoma (CMZL) is considered part of the broad group of extranodal marginal zone B-cell lymphomas in the 2008 WHO classification. Distinguishing primary CMZL (PCMZL) from secondary CMZL (SCMZL) is of utmost importance for prognostic and therapeutic approach.
Design: We analyzed the clinicopathologic, phenotypic and genotypic features of a series of 21 patients that showed histopathologic features of CMZL in at least 1 biopsy either at initial presentation or at relapse.
Results: Nine patients were male and 12 were female. Median age was 48 years (range: 23 to 72). Six patients had synchronous or metachronous documented extracutaneous disease. Three cases had a breast MALT lymphoma and other extranodal sites included parotid gland, nasopharynx and bone marrow in one case each, respectively. Morphological and clinical dermatologic features of SCMZL were indistinguishable from cases with PCMZL. All cases showed monotypic plasma cells with immunostains or in situ hybridization for κ and λ; 14 cases showed monotypic κ expression, and 7 cases showed monotypic λ expression. No differences were found between these two groups. Nevertheless, all tumors with primary cutaneous involvement had class-switched heavy chain, with numerous admixed T cells (p=0.036) and clusters or small aggregates of dendritic plasmocitoid cells CD123+ (p=0.013), whereas IgM positive plasma cells were observed in 5 out of 6 SCMZL, mixed with isolated CD123+ cells and scattered T cells. Moreover T cells in PCMZL, more often express a CD4+ phenotype.
Conclusions: Our observations indicate that PCMZL are distinct from secondary cutaneous forms of extracutaneous MALT lymphomas and are characterized by the expression of class-switched immunoglobulins with dense infiltration of reactive T cells and clusters or aggregates of CD123+ plasmocytoid dendritic cells.
Category: Dermatopathology

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 120, Tuesday Morning


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