PRIMARY LOW-GRADE ENDOMETRIAL B-CELL LYMPHOMA

We describe three cases of primary low-grade B-cell lymphoma of the en dometrium and contrast the histological, immunohistochemical, and mole cular features with two examples of benign endometrial lymphoid infilt rates. The first case was an incidental finding in a curettage specime n, confirmed on a subsequent hysterectomy. The other two cases of lymp homa were incidental findings on hysterectomy procedures performed for prolapse and cervical dysplasia, respectively. All three lymphomas oc curred in patients in their sixties; none formed gross tumors. Histolo gic examination revealed lymphoid nodules adjacent to endometrial glan ds. The lymphoid cells showed mild nuclear enlargement and slight irre gularities of the nuclear contour. None of the three patients had evid ence of disease outside the endometrium by physical examination, bone marrow biopsy, or sampling of pelvic lymph nodes. Immunohistochemistry demonstrated a B-cell phenotype of the lymphoid cells (CD20 positive, CD79a positive) with aberrant coexpression of the T-cell-associated m arker CD43. Polymer ase chain reaction (PCR) amplification of the VDJ region of the immunoglobulin heavy-chain was performed on DNA isolated from paraffin sections. These studies demonstrated a clonal prolifera tion of B-lymphocytes in two cases. In the third case, a faint band wa s found superimposed on a background smear, suggesting the presence of a B-cell clone. In contrast, the two examples of histologically benig n lymphoid aggregates of the endometrium consisted predominantly of T cells with rare B-lymphocytes; there was no evidence of coexpression o f CD43 by B-cells. The PCR amplification from the benign lymphoid aggr egates did not support a clonal process, Primary lymphoid neoplasms of the endometrium are rare, and all cases described so far have been hi gh-stage, high-grade neoplasms. To our knowledge, this is the first re port of primary low-grade B-cell lymphoma of the endometrium, presumab ly arising from endometrial lymphoid tissue.