Cutaneous Double-Hit B-Cell Lymphoma: An Aggressive Form of B-Cell Lymphoma With a Propensity for Cutaneous DisseminationMagro, Cynthia M. MD; Wang, Xuan MD, PhD; Subramaniyam, Shivakumar PhD; Darras, Natasha MD; Mathew, Susan PhDAmerican Journal of Dermatopathology: April 2014 - Volume 36 - Issue 4 - p 303–310 doi: 10.1097/DAD.0b013e31829beaa7 Original Study Abstract Author Information Abstract: Diffuse large cell B-cell lymphoma of the skin is most commonly represented by diffuse large cell variants of primary cutaneous follicle center cell lymphoma and the leg-type lymphoma. In a minority of cases, the infiltrates are an expression of stage 4 disease of established extracutaneous B-cell lymphoma. We describe 3 patients with an aggressive form of B-cell lymphoma secondarily involving the skin. Two of the patients were in the ninth decade of life, whereas 1 patient was 34 years of age. In the elderly patients, there was an antecedent and/or concurrent history of follicular lymphoma, whereas in the younger patient, the tumor was a de novo presentation of this aggressive form of lymphoma. The elderly patients succumbed to their disease within less than a year from the time of diagnosis, whereas 1 patient is alive but with persistent and progressive disease despite chemotherapeutic intervention. The infiltrates in all 3 cases were diffuse and composed of large malignant hematopoietic cells that exhibited a round nucleus with a finely dispersed chromatin. Phenotypically, the tumor cells were Bcl-2 and CD10 positive, whereas Bcl-6 and Mum-1 showed variable positivity. One case showed combined Mum-1 positivity along with an acute lymphoblastic lymphoma phenotype, including the absence of CD20 expression. In each case, there was a c-MYC and BCL2/IGH rearrangement diagnostic of double-hit lymphoma. In one case, there was an additional BCL6 rearrangement, defining what is in essence triple-hit lymphoma. In conclusion, double-hit lymphoma is an aggressive form of B-cell neoplasia resistant to standard chemotherapy regimens, which in many but not all cases represents tumor progression in the setting of a lower grade B-cell malignancy. Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY. Reprints: Cynthia M. Magro, MD, Department of Pathology and Laboratory Medicine, Room F-309, Box 58, 1300 York Ave, Weill Medical College of Cornell University, New York, NY 10065 (e-mail: firstname.lastname@example.org). The authors declare no funding or conflicts of interest. © 2014 by Lippincott Williams & Wilkins.