Abstract
Plasmablastic lymphoma (PBL) is a rare and recently described entity of large B-cell lymphoma. It predominantly occurs in the oral cavity of human immunodeficiency virus (HIV)-positive patients and exhibits a highly aggressive clinical behavior without effective treatment. Recently, sporadic cases describing PBL in extraoral locations of HIV-negative patients have been reported; frequently in patients with underlying immunosuppressive states. To develop the understanding of PBL, the current study reports the unusual presentation of duodenal PBL and reviews the pathogenesis, immunohistochemical features, clinical and differential diagnoses, as well as the treatment of PBL as described in previous studies. The case of a 75-year-old female with duodenal PBL without definite immunosuppression is presented in the current report. The tumor was composed of large B-cell-like cells, and was positive for cluster of differentiation 138 and melanoma ubiquitous mutated-1, with ~80% of the tumor cells positive for Ki-67. The features of the tumor were as follows: Extraoral location, HIV-negative, immunoglobulin M λ-type M protein expression, light chain restriction (monoclonal) and Epstein-Barr virus-encoded small RNA-negative, which are considered to be unusual for PBL. These unusual features complicate the differentiation of PBL from other plasma cell diseases. To the best of our knowledge, this is the first study to report a case of duodenal PBL in an immunocompetent patient. To date, the standard treatment of PBL remains elusive, however, the most commonly administered chemotherapy treatments are CHOP [intravenous cyclophosphamide (750 mg/m(2), day 1), intravenous doxorubicin (50 mg/m(2), day 1), intravenous vincristine (1.4 mg/m(2), day 1) and prednisone (100 mg, days 1-50)]-like regimens. The patient was administered two cycles of CHOP chemotherapy for 56 days, however, ultimately succumbed as a result of disease progression. Therefore, PBL represents a diagnostic and therapeutic challenge. PBL must be considered in the differential diagnosis of gastrointestinal tumors in daily practice, even in immunocompetent patients. Furthermore, CHOP does not appear to be an optimal treatment regimen and more intensive regimens are required.