Malignant transformation in an atypical endometrial cyst of the ovary

Editor, Endometriosis is the occurrence of endometrium (glandular epithelium and endometrial stroma) outside the endometrial cavity, most commonly in the ovary. Like the uterine endometrium, ectopic endometrium may proliferate and transform into atypical hyperplasia and carcinoma. Atypical endometriosis is characterized by architectural proliferation and cytological atypia, and is reported to possess premalignant potential. The incidence of malignancy in endometriosis is 1.1%–3%.[] A 27-year-old female presented with primary infertility and a history of pain abdomen. On per vaginum examination, a bulky mass was felt arising from the uterus measuring 26 weeks. Per speculum examination showed a nulliparous os and was otherwise unremarkable. On magnetic resonance imaging of the pelvis, a subserous leiomyoma measuring 16 cm × 14 cm × 12 cm, with increased vascularity was seen arising from the lateral wall of the uterus. The left ovary showed a complex cyst measuring 3.5 cm × 3 cm × 1 cm. The right ovary was unremarkable. Exploratory laparotomy was carried out and myomectomy, cyst enucleation, and right internal iliac ligation were performed. We received a uterine soft tissue mass along with an ovarian cystic lesion. The uterine soft tissue mass was consistent with the diagnosis of leiomyoma. Gross examination of the cystectomy specimen revealed a brown-colored cyst filled with hemorrhagic fluid, with wall thickness varying from 0.5 to 1.5 cm. Serial sections from the cyst wall showed lining epithelium with underlying subepithelial tissue showing focal endometrial stroma and hemosiderin laden marcrophages. Focally, lining epithelial cells were seen to be present in multiple layers. Individual cells were large, with high nucleocytoplasmic ratio, moderate amount of dense eosinophilic cytoplasm, enlarged vesicular nuclei showing stratification, and protrusion into the apical region. The nuclei were showed moderate to marked pleomorphism and prominent nucleoli. Well-differentiated endometrioid adenocarcinoma was seen to originate from the lining epithelium in the thickened area of the cyst wall. Focal squamous metaplasia was also observed [Figure 1]. Lining epithelium of the cyst wall and that of the malignant glands showed positivity for estrogen and progesterone receptors confirming endomterial origin [Figure 2]. A diagnosis of well-differentiated endometrioid adenocarcinoma arising from an atypical endometrial cyst of the ovary was made. Endometriosis is a common disorder, however, rarely, ectopic endomterium may proliferate and transform into atypical hyperplasia and carcinoma. In the present case, atypical endometriosis with malignant transformation was discovered as an incidental finding. Atypical ovarian endometriosis was first described by LaGrenade and Silverberg in 1988.[] It refers to the presence of atypical or karyotypical changes in ectopic endometrial epithelia. The diagnostic criteria are as follows: (1) the nuclei of ectopic endometrial epithelia are heavily or lightly stained, with medium to severe degree of multiformity; (2) the ratio of nucleus to cytoplasm is increased; (3) cells congregate showing in layers or grouped protrusions; (4) atypical glandular structures are seen.[,] The diagnosis is confirmed when three or more criteria are met. Malignant transformation of endometriosis was first described by Sampson[] in 1925 with the following criteria (1) clear evidence of endometriosis close to the tumor, (2) documentation of malignant foci arising in endometrioid lesions, rather than originating outside the lesion, and (3) the presence of tissue resembling endometrial stroma surrounding the characteristic glands. An additional criteria added by Scott[] were demonstration of a histologically proven transition from benign endometriosis to cancer. In the present case, all criteria of malignant transformation in endometriosis were present. Origin of irregular glandular structures from the lining epithelium, the presence of endometrial stroma around the malignant glands and proximity of the tumor to endometriosis was seen. About 60%–80% cases of endometrioid ovarian cancers which are associated with endometriosis, arise in the presence of atypical endometriosis. Terada et al. reviewed 15 cases of endometrioid adcenocarcinoma of the ovary and found that 4% of the cases were associated with endometriosis, all of which were atypical endometriosis.[] The presence of atypia in an endometrial cyst should warrant a careful examination of the entire cystic lining and strict follow-up of the patient. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. REFERENCES - 1. Stern RC, Dash R, Bentley RC, Snyder MJ, Haney AF, Robboy SJ. Malignancy in endometriosis: Frequency and comparison of ovarian and extraovarian types Int J Gynecol Pathol. 2001;20:133–9 - 2. LaGrenade A, Silverberg SG. Ovarian tumors associated with atypical endometriosis Hum Pathol. 1988;19:1080–4 - 3. Sampson JA. Endometrial carcinoma of the ovary arising in endometrial tissue in that organ Arch Surg. 1925;10:1–12 - 4. Scott RB. Malignant changes in endometriosis Obstet Gynecol. 1953;2:283–9 - 5. Terada T. Endometrioid adenocarcinoma of the ovary arising in atypical endometriosis Int J Clin Exp Pathol. 2012;5:924–7