Benign mesothelioma of the uterus
Benin mesothelioma of the uterus was first described in 1942. The old name of adenomatoid tumor fell due to the presence of structure's pseudoglandular suggestive of an adenoma.
Benin mesothelioma generally affects the genital tract.
This tumor is more frequently observed in humans in the epididymis, but it also affects the female genital tract, sitting at the trunk (48%), uterus (42%) or yet the ovary (7%). It is the most common benign tumor of the fallopian tube.
However, rare cases of mesothelioma have been reported in Benin at the heart of the adrenal gland, mesentery, pleura and retroperitoneal.
The histogenesis of these tumors has long been debated. Assumptions of epithelial, endothelial, mesothelial or Müllerian were discussed. Immunohistochemical and ultrastructural studies have now established more recent origin of these tumors mesothelial justifying the term mesothelioma Benin.
The incidence of mesothelioma of the uterus Benin on hysterectomy was 0.37% in the series of Huang et al. and 1.2% according to Mainguene. However, the true incidence of this tumor is probably more important because it often goes unnoticed because of its small size and its resemblance to leiomyomas and adenomyomas.
The average age of onset is 41 years, with extremes ranging over from 20 to 85 years. Our patient, aged 30, was relatively young.
It is most often discovered incidentally but may prove, as in our case, by abdominal pain, cycle disorders usually caused by concomitant lesions (endometriosis or leiomyoma). Preoperative assessment does not suspect the diagnosis. Indeed, the sonographic appearance is that of a leiomyoma or uterine adéomyome However, MRI may have a definite contribution in cystic forms.
The most benign mesothelioma of the uterus is subserous or located at the outer layers of the myometrium. The posterior surface of the uterus, particularly near the bottom or horns, is a location of choice. In our case, mesothelioma had a classic location: subserous, at the posterior surface of the uterus.
Benin mesothelioma of the uterus occurs most often as a solitary nodule. The macroscopic appearance is similar to that of leiomyoma. This is a firm mass, well circumscribed but less clearly a leiomyoma, write to yellow cup, more or less fasciculata. The mean diameter is close to 2 cm.. However, other forms of the diffuse or multinodular uterus have been described; these are rare and benign lesions, reported almost exclusively in patients treated with immunosuppressants in renal transplantation.
Benin mesothelioma of the uterus is often associated with other uterine tumors, usually benign (leiomyomas in 59-80% of cases, adenomyomas in 16.6% of cases). The coexistence of this tumor with cervical cancer or endometrial cancer was reported in the literature.
Several histological types were found. Quigley and Hart described four types: adenoid, angiomatoid (most common), solid and cystic. A combination of two or more components is possible.
The shape of cystic mesothelioma of the uterus Benin is the rarest and is localized in subserous or intramural. Two of the five cases of mesothelioma reported in the literature cystic tumors were multilocular with the presence of a dense component. The three other cases, like our patient, have purely cystic tumors without solid quota or partitions.
Histologically, the lesion consists of a proliferation of cuboidal cells or flattened, arranged in granuliform structures, pseudo-vascular or trabecular, embedded between bundles of hyperplastic smooth muscle fibers. Immunohistochemical study revealed a depression of cytokeratins and vimentin indicating a mesothelial origin. Electron microscopy, cells have the ultrastructural features of mesothelial cells: microvilli, tonofilament bundles, desmosomes between many cells, but absent from the basement membrane is also thickened. The diagnosis of adenomatoid tumor multinodular based on histological and adenomatoid angiomatosis, and on the immunohistochemical profile. Immunohistochemical and ultrastructural studies have now established the mesothelial origin of these tumors justifying the term mesothelioma Benin.
Adenocarcinoma is a differential diagnosis of mesothelioma Benin cancer. At the histological level, Benin mesothelioma of the uterus is distinguished by a more regular architecture, cells lacking atypia and a tumor that pushes at most endometrial without infiltrate.
In addition, adenocarcinoma does not express vimentin. Similarly, vascular proliferation such as lymphangiomas, hemangiomas or angiomyoma can raise difficult problems of differential diagnosis with ultrasound forms angiomatous or cystic benign mesothelioma. Light microscopic immunohistochemistry shows in the case of tumors of vascular origin anti cytokeratin antibody negative.
Evolution of Benin mesothelioma of the uterus is always favorable, without risk of recurrence or malignant transformation.
However, it can progress to a gradual increase in size with tumors larger than 10 cm.
In the rare cases where the diagnosis is mesothelioma Benin worn preoperatively, limited surgical excision is indicated. A hysterectomy can be performed because other uterine lesions (adenomyosis and / or leiomyoma) associated. In our case, resection of the prominent dome appears to be sufficient given the lack of risk of recurrence and malignant transformation.
CONCLUSION
Benin mesothelioma of the uterus is a histological diagnosis of tumor. Preoperative assessment does not suspect the diagnosis because of the similarity with ultrasonographic leiomyoma. The cystic form reported in our work is very rare. Mesothelial origin is now well established. Evolution of Benin mesothelioma of the uterus is always favorable, without risk of recurrence or malignant transformation. The elective treatment is surgical excision limited.
