Primary cutaneous marginal zone B-cell lymphoma with anetoderma: spontaneous involution plus de novo clonal expansion.

We describe a rare case of primary cutaneous marginal zone B-cell lymphoma (PCMZL) in a 33-year-old male affected by hepatitis B virus (HBV)-related chronic active hepatitis. The patient presented with multiple cutaneous papulonodular lesions characterized by polymorphic immunomorphology, with inverse pattern of immunoglobulin light chain restriction in two different lesions, coupled with mucin deposition and anetoderma in a third lesion. The involution of lesions of PCMZL with secondary anetoderma has been previously described, but this has not been reported in the context of multiple lesions showing differing immunoglobulin light chain restriction. We speculate that these findings may be secondary to a variable interaction between a chronic antigenic stimulus (i.e. HBV) and its specific immune response.