A case of primary cutaneous marginal zone B-cell lymphoma

We report a case of primary cutaneous marginal zone B-cell lymphoma. A 23-year-old male presented with red nodules on his back for 5 years. Physical examination revealed multiple demarcated red nodules on the back, sized 5 mm×5 mm to 10 mm×15 mm, with smooth surface, soft texture, but without scales and tenderness. Histopathology showed nodular lymphoid hyperplasia in the dermis and subcutaneous tissue, partial follicular atrophy, and small- to medium-sized centrocytoid and monocytoid cells surrounding the follicles and eccrine glands, which locally infiltrated into the subcutaneous adipose tissue. Immunohistochemistry revealed positive for CD20, CD21(FDC network), CD23(FDC network), kappa, Bcl-2, CD43 (partially), Ki-67 (10%), and negative for CD3, CD4, CD5, CD8, Lambda, Bcl-6 and Cyclin-D1. The diagnosis was primary cutaneous marginal zone B-cell lymphoma. The patient declined the treatment and was lost follow-up 1 year later.