**21. Histological features of pseudoxanthomatous salpingitis**

This is a form of tubal inflammation characterized histologically by the presence of histiocytes filled with lipofuscin and hemosiderin. In multiple sections there is always a typical focus of endometriosis of the fallopian tube and /or the ovary.

Pathological Aspects of Endometriosis 109

There are a few reports of endometriosis that develops in male patients under hormonal therapy for prostatic carcinoma. The usual sites that endometriosis develops are: the urinary

Peritoneal decidual reaction is an incidental finding, usually discovered during a caesarian section or postpartum tubal ligation, as small whitish or yellow peritoneal nodules, mimicking metastatic disease. Histological examination shows an extensive decidual reaction of the sub-mesothelial mesenchymal cells. This reaction may also be observed at the omentum, appendix and uterine ligaments. Due to the presence of hyperemic vessels in these lesions, the development of hemoperitoneum during labor may be a rare complication Peritoneal leiomyomatosis presents as multiple small white nodules in the peritoneum and arise from smooth muscle-cell metaplasia of the sub-mesothelial mesenchymal cells. This is a self-limiting disease successfully treated with GHRH antagonists. There is no evidence that these two conditions are related to endometriosis, but they probably represent lesions

The exact rate of neoplastic transformation of endometriosis is not known because of the fact that the neoplasm obliterates the endometriotic features of the underlying lesion. Neoplastic transformation of both the glandular and the stroma component of endometriosis may occur. There are benign and malignant lesions that may develop in endometriotic foci. Tumor-like benign lesions in the form of nodules or even larger, uterus-like masses are reported. Histological examination showed hyperplastic chances of the glandular component of endometriosis and extensive leiomyomatous metaplasia of the stromal component. These lesions may be described as endometrioid adenomas or endometrioid cystadenomas. Malignant transformation of the glandular component presents the pathological features of an endometrioid adenocarcinoma. In 75% of cases the malignant transformation of the glandular component arises in the ovaries. Ovarian endometrioid and clear cell adenocarcinomas are strongly related to ovarian endometriosis and atypical endometriotic lesions were observed in 60% of those carcinomas. Endometriosis -associated ovarian adenocarcinomas are well differentiated tumors in stage I and have a better prognosis that the other ovarian epithelial carcinomas. There are strict criteria for establishing the origin of an adenocarcinoma from endometriosis: Both elements must coexist, atypical hyperplastic and dysplastic changes of endometriosis must be observed and t no extension of carcinoma from another source is established. Extra ovarian sites where malignant transformation of endometriosis is reported are the rectovaginal septum and the colon (Benoit et al, 2006). Malignant transformation of the stromal component of the endometriosis gives rise to stromal sarcomas similar to uterine stromal tumors (Dogan et al, 2006, Han, 1998). In the table below, tumor-like conditions and tumors, benign and malignant, associated with endometriosis are presented. This classification is based on the WHO classification of Ovarian Tumors (IARC Press, Lyon 2003) modified to contain the

bladder, the prostate, the para-testicular region and the abdominal wall.

**29. Histological features of the peritoneal decidual reaction and the** 

**28. Endometriosis in male patients** 

of the secondary Mullerian system (Clement, 1995).

**30. Neoplasms related to endometriosis** 

tumor-like conditions and premalignant changes.

**peritoneal leiomyomatosis** 
