Immunoreactive endometritis

Primary Extranodal Marginal Cell Lymphoma, MALT Type, of the Endometrium Arising in a Patient With Rheumatoid Arthritis: Report of a Case

Primary marginal zone B-cell MALT-type lymphomas of the uterine corpus are exceedingly rare entities, with only 6 cases reported in the literature to date. We present the additional case of a 70-yr-old white woman who underwent a laparoscopic total hysterectomy with bilateral salpingo-oophorectomy for an asymptomatic ovarian cyst. At microscopic examination, endometrial samples showed a dense, nodular lymphocytic infiltrate, suggestive of a lymphoproliferative disorder. Morphology, immunohistochemistry, and molecular analysis supported the diagnosis of MALT-type lymphoma of the endometrium. Benign reactive conditions, such as endometritis and other small B-cell lymphomas were ruled out. Moreover, we investigated the pathogenesis of our case, focusing on Chlamydia trachomatis infection, chromosomal translocations affecting the NF-kB pathway, and discussing the role of autoimmunity in the development of MALT-type lymphomas.

Primary extranodal marginal zone B-cell lymphoma of MALT type of the endometrium

BACKGROUND

Only one case of primary extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) of the endometrium has been previously reported.

CASE

A 65-year old patient presented with postmenopausal bleeding. She was found to have endometrial polyps. The endometrial curettings showed a dense lymphoid infiltrate that was suggestive of a lymphoproliferative disorder. Histological examination of the total abdominal hysterectomy revealed primary extranodal marginal zone B-cell lymphoma (MALT-type lymphoma) of the endometrium. The diagnosis was supported by morphology, immunohistochemistry, and molecular analysis.

CONCLUSIONS

Extranodal MALT lymphoma of the endometrium is exceptionally rare although the female genital tract is rich in mucosa and the presence of MALT tissue has been previously described. The diagnosis of lymphoproliferative disorder in this case was initially made on endometrial curettings. Although most lymphoid aggregates within endometrial curettings are due to reactive conditions such as endometritis, the possibility of lymphoma must be kept in mind when dense lymphoid aggregates or atypical lymphoid cells are present in the curettings.

Primary low-grade endometrial B-cell lymphoma

We describe three cases of primary low-grade B-cell lymphoma of the endometrium and contrast the histological, immunohistochemical, and molecular features with two examples of benign endometrial lymphoid infiltrates. The first case was an incidental finding in a curettage specimen, confirmed on a subsequent hysterectomy. The other two cases of lymphoma were incidental findings on hysterectomy procedures performed for prolapse and cervical dysplasia, respectively. All three lymphomas occurred in patients in their sixties; none formed gross tumors. Histologic examination revealed lymphoid nodules adjacent to endometrial glands. The lymphoid cells showed mild nuclear enlargement and slight irregularities of the nuclear contour. None of the three patients had evidence 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 marker CD43. Polymerase 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 proliferation of B-lymphocytes in two cases. In the third case, a faint band was found superimposed on a background smear, suggesting the presence of a B-cell clone. In contrast, the two examples of histologically benign lymphoid aggregates of the endometrium consisted predominantly of T cells with rare B-lymphocytes; there was no evidence of coexpression of CD43 by B-cells. The PCR amplification from the benign lymphoid aggregates did not support a clonal process. Primary lymphoid neoplasms of the endometrium are rare, and all cases described so far have been high-stage, high-grade neoplasms. To our knowledge, this is the first report of primary low-grade B-cell lymphoma of the endometrium, presumably arising from endometrial lymphoid tissue.