This was a rare case of primary tubal lymphoma incidentally discovered during surgery for endometrial carcinoma. At the time of surgery for endometrial carcinoma, surgeons often request an intraoperative pathology consultation for evaluation of disease extent that at least in part guides surgical management. Our patient showed a low grade endometrial adenocarcinoma with superficial myometrial invasion. With this finding alone, she would not need further staging surgery after hysterectomy and salpingo-oophorectomy. However, her left fallopian tube showed a small nodule suspicious for malignancy. Thus the intraoperative interpretation of this nodule became critical to the surgical management because a full staging procedure including pelvic lymph node sampling would be suggested if the nodule were metastatic endometrial carcinoma. Although carcinoma may show distinct gross features, accurate diagnosis relies on frozen section. In our case, frozen section of the left fallopian tube nodule displayed an atypical lymphoid proliferation instead of carcinoma, thus saving the patient from more surgery. The nodule on permanent sections proved to be a primary follicular lymphoma.
Although primary extranodal lymphoma is not infrequent, primary lymphoma of the fallopian tubes is very unusual. Only rare cases of primary tubal lymphoma have been reported. In one case, a 68 year old woman underwent hysterectomy and bilateral salpingo-oophorectomy for a tubo-ovarian mass and was found to harbor a primary follicular lymphoma of the tube, associated with hydrosalpinx and tubo-ovarian abscess . Treatment and outcome information was not available for this patient. Another case was described in a 34 year old woman who presented with pelvic pain and an adnexal mass . Pathologic examination of the excised adnexal mass revealed a primary tubal lymphoma of the mucosa associated lymphoid tissue type. The patient was disease free one year after surgery without chemotherapy. More recently, primary T-cell lymphoma of bilateral fallopian tubes was reported in a 51 year old woman who had presented with a pelvic mass . She maintained remission for more than 5 years after treatment with chemotherapy. These cases show that primary tubal lymphoma, despite its rarity, can show various histologic subtypes including follicular center type, mucosa associated lymphoid tissue type, and T-cell lymphoma. We now describe the second case of primary follicular lymphoma of the fallopian tube. While the other patients in the literature presented with either pelvic pain or mass, the lymphoma in our patient was an incidental finding in a surgical procedure performed for endometrial carcinoma.
The etiology of primary tubal lymphoma is unclear. The association between chronic inflammation and certain types of extranodal lymphomas may have implications for lymphomas of the fallopian tube. Indeed, one previously reported case of primary tubal lymphoma showed associated hydrosalpinx and tubo-ovarian abscess . It was, however, not clear whether tubal inflammation occurred before or after lymphoma in this patient. Because chronic salpingitis usually shows marked tubal distortion with hydrosalpinx, it is unlikely the cause of lymphoma in our patient who showed an otherwise normal appearing fallopian tube.
Lymphoma of the fallopian tube should be distinguished from other diseases. Carcinoma is usually easily distinguished from lymphoma because of the distinct histologic features between the two diseases. While carcinoma usually shows cellular cohesion, lymphoma often displays a diffuse pattern of noncohesive cells. Small cell neuroendocrine carcinomas may histologically simulate lymphoma, but nuclear molding, trabecular formation, and rosettes present in small cell carcinoma are absent in lymphoma. In difficult cases, immunostains for cytokeratin, CD45, synaptophysin, and chromogranin help make the correct diagnosis.
Lymphoma of the fallopian tube should also be distinguished from a chronic inflammatory process. While an inflammatory process shows a cellular heterogeneity, lymphoma usually displays a diffuse infiltration by a monomorphic population of lymphoid cells. Immunostains can help determine the clonality of lesional cells in difficult cases. Diagnostic challenges may arise in evaluating chlamydial salpingitis with a florid lymphofollicular hyperplasia mimicking follicular lymphoma . Unlike follicular lymphoma that is positive for BCL-2, however, follicular hyperplasia is negative for BCL-2.
Accurate subtyping of lymphoma is imperative because various types differ in their rates of progression, overall prognosis, and response to individual forms of treatment. Although different lymphomas may show distinct histologic features, special studies play an important role in subtyping. The lymphoma in our case histologically displayed a follicular pattern consistent with follicular center type. BCL-2 and BCL-6 immunopositivity and t(14, 18) translocation confirmed a follicular lymphoma.
It is also important to distinguish a primary tubal lymphoma from secondary involvement. In general, distinction between primary and secondary lymphomas is facilitated by physical examination, radiologic imaging, and bone marrow biopsy. Since our patient did not show lymphadenopathy or evidence of lymphoma elsewhere, the tumor in the left fallopian tube was consistent with a primary tubal lymphoma. Our patient did not receive chemotherapy and remained disease free for more than 1 year.