Background: Primary cutaneous marginal zone B-cell lymphoma (MZCL) has recently been described. Differentiation from follicular centre cell lymphomas and lymphocytomas is often difficult due to insufficient experience and a lack of large series of patients.
Objectives: To characterize primary cutaneous MZCL better, we report clinical, histopathological, immunophenotypic and molecular genetics features in a series of 22 patients.
Methods: All patients were treated and followed up at the same institution. Diagnosis of MZCL was based on the World Health Organization classification criteria. All samples were routinely tested with a wide panel of monoclonal antibodies. DNA was extracted from every sample following standard methods. IgH rearrangement and t(14;18)(q32;q21) studies were performed in all samples.
Results: Twenty-two patients (20 men, two women; mean age 50 years, range 24-77) were included. The mean follow-up was 43 months. Seventy per cent of patients presented with characteristic skin lesions on the trunk or extremities, consisting of deep red to violaceous infiltrated plaques, nodules or tumours frequently surrounded by diffuse or annular erythema. Four patients presented with lesions on the head and neck area. Two patients had disseminated skin lesions. The main histopathological features were non-epidermotropic, dense lymphocytic infiltrates mainly distributed in a nodular pattern. Adnexal involvement was usually present, with eventual formation of lymphoepithelial complexes. Cytologically, the infiltrate was polymorphous with marginal zone B cells and B-monocytoid cells. Blastoid CD30+ cells were often observed. Colonized reactive germinal centres and lymphoplasmocytoid differentiation were frequently present. Neoplastic cells were CD20+, CD79a+, CD5- and CD10-. Monotypic expression of light chains was observed in 18 cases (13 kappa; five lambda). Clonal IgH rearrangements were detected in 14 cases. The bcl-2 mutation t(14;18)(q32;q21) was demonstrated in two cases. Most patients were treated with local radiotherapy. Complete response rate with this approach was 100%. Six patients (27%) had skin recurrences from 6 months to 8 years after first treatment. Five patients (23%) had extracutaneous involvement. Two of them had a large cell transformation and one died of lymphoma. Three of four patients with head and neck presentation developed extracutaneous disease.
Conclusions: MZCL appears to be a well recognizable entity, clinically, histologically and immunophenotypically. Although prognosis is generally good, the disease has potential for skin as well as extracutaneous recurrences. Large cell transformation and head and neck presentation may be associated with a worse prognosis.