In a recent study published in the International Journal of Clinical & Experimental Pathology, a team of researchers from the Department of Pathology and Translational Genomics in the Samsung Medical Center at Sungkyunkwan University School of Medicine in South Korea describe an unusual case of decimalized endometriosis detected in pelvic lymph nodes. According to the researchers, misdiagnosis of this condition as a metastatic tumor can be avoided by an awareness of benign inclusions, supported by results for the immunohistochemical staining.
A variety of benign ectopic inclusions can occur ectopically within lymph node parenchyma, including thyroid follicles, mammary acini and ducts, salivary tissue and mullerian-type glands have been described.
Endometriosis in the pelvic lymph nodes is also a frequent incidental finding. Similar to normal endometrium, endometriotic foci can become decidualized during pregnancy in response to high levels of circulating progestin.
Decidualization is the process of conversion of the normal endometrium during pregnancy into a specialized uterine lining adequate for optimal accommodation of gestation, a change that is induced by progesterone and involves hypertrophy of the endometrial stromal cells, thickening of the normal endometrium and formation of decidua.
However, decidualized intranodal endometriosis occurring in a postmenopausal woman remains poorly understood. To address this clinical unmet issue, in their study titled “Decidualization of intranodal endometriosis in a postmenopausal woman,” Hyun-Soo Kim and colleagues report a case of a 52-year-old Korean woman that had a 2-month history of progressive abdominal discomfort and a 1-day history of dyspnea. Her medical history included hypothyroidism. She experienced menopause at the age of 47 years, and had taken a combined course of hormone replacement therapy for 6 years.
After physical examination, the clinicians observed a palpable mass in the right lower abdomen. Blood tests revealed increased CA-125 level (1687.3 U/mL). Examination with computed tomographic scan revealed marked ascites and a large, heterogeneous, solid and cystic mass arising from the adnexa. She also had 4 L of straw-colored ascitic fluid and a right ovarian mass, and some enlarged pelvic and para-aortic lymph nodes.
Final histopathologic examination of the right ovarian tumor revealed the presence of primary stage IA clear cell carcinoma.
Based on these results, the researchers suggest that even though the phenomenon of ectopic deciduous is common during pregnancy, decidualization of intranodal endometriosis appears very uncommon in postmenopausal women. In their study, the researchers indicate that surgical pathologists should be aware of this entity, because it can be misinterpreted as a neoplastic process.