Cutaneous B-cell lymphoproliferative disorders: report of the 2011 Society for Hematopathology/European Association for Haematopathology workshop.

The diagnosis and classification of the cutaneous B-cell lymphomas can be quite a challenge, with a definitive diagnosis sometimes being elusive, even when an extensive workup has been performed. Distinction of benign from neoplastic disorders can be difficult, with some hyperplasias mimicking lymphomas and vice versa. There are only a limited number of skin-specific B-cell lymphomas, including primary cutaneous follicle center lymphoma and primary cutaneous diffuse large B-cell lymphoma, leg type. Cutaneous marginal zone lymphomas have distinctive features but are classified with the other mucosa-associated lymphoid tissue lymphomas. It is important, however, to also remember that many other B-cell lymphomas/ plasma cell neoplasms can primarily, or more often secondarily, involve the skin. Some may mimic one of the skin-specific lymphomas but have very different clinical implications. Iatrogenic and senescent immunodeficiency-associated lymphoproliferative disorders that are often Epstein-Barr virus (EBV) positive can also primarily involve the skin, including cases also known as EBV-positive mucocutaneous ulcer.