Endometriosis of the pancreas presenting as a cystic pancreatic neoplasm with possible metastasis.

Abstract: The authors report a case of endometriosis that presented as a cystic mass in the tail of the pancreas, leading to extensive evaluation and ultimately a major surgical resection. The diagnosis was made by histopathological evaluation, revealing endometrial glands and stroma in the wall of the mass with hemorrhagic fluid in the cystic lumen, compatible with pancreatic involvement by an endometrial cyst.

Key Words: cyst, endometriosis, pancreas

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Endometriosis is defined as the presence of endometrial tissue in ectopic sites outside the endometrium and myometrium. While it occurs in 15% of women of reproductive age, it rarely involves the pancreas. Endometriosis is a condition in which endometrial tissue grows outside the uterus and attaches to various organs in the body. We report a case of endometriosis of the pancreas, which to our knowledge is the first reported case involving endometriosis presenting as a potentially metastatic pancreatic growth, due to other confounding clinical and diagnostic findings discussed below.

Case Report

A 34-year-old white female was admitted to the hospital for evaluation and treatment of severe abdominal pain. Her history dated back 3 years with intermittent attacks of left upper quadrant pain. She remained free from pain between attacks. She had no history of abdominal trauma, and no prior surgeries. She reported no history of blood in her stool or history of coffee-ground emesis or hematemesis. She denied weight loss. She did not have any change in appetite or bowel habits. She also denied any history of alcohol use or abuse, or smoking. She underwent a computed tomographic (CT) scan which showed an 8 X 8 cm cystic mass located in the tail of the pancreas abutting the spleen. Carcinoembryonic antigen and cancer antigen 19-9 were within limits. The chest radiograph showed a new pulmonary nodule in the right lower lobe of the lung near the diaphragm. The CT scan of the chest showed a small nodule in the left lung as well as enlarged hilar and mediastinal lymph nodes in addition to the irregular 1.5 X 2.2 cm mass in the right lower lobe of the lung near the diaphragm, suggesting the possibility of metastatic disease. She was referred for CT-guided biopsy of the pancreatic tail mass. Approximately 100 mL of dark brown, hypocellular fluid containing occasional macrophages was obtained by fine needle aspiration. Laboratory testing revealed an elevated amylase level in the fluid. The CT scan findings were followed up with a positron emission tomography scan, which showed hypermetabolic foci in the right and left lower lobes of the lung consistent with the CT-identified masses, and several hypermetabolic foci in the right paratracheal, subcarinal, and hilar regions. No hypermetabolic lesions in the areas of the pancreas or abdomen were noted. A repeat CT scan of the abdomen showed reaccumulation of the cystic collection in the tail of the pancreas with no other new identifiable lesions. Based on the potential for a cystic pancreatic neoplasm, this was pursued further with exploratory laparoscopy. Laparoscopy revealed small plaque-like lesions on the right diaphragm and liver, suspected neoplastic areas on the spleen, and an 8 X 8 cm cyst in the tail of pancreas. Biopsies of these suspicious lesions were obtained with frozen-section analysis, and showed atypical glandular structure, and the possibility of metastatic adenocarcinoma could not be excluded. Open laparotomy was then performed, with no additional lesions identified and normal ovaries and uterus noted. The patient then underwent distal pancreatectomy and splenectomy for a presumptive diagnosis of a cystic neoplasm of the pancreas.

Discussion

In our case, an endometrial cyst was located in the tail of the pancreas, something that is rarely encountered in clinical practice. Histopathological demonstration of endometrial tissue in the mass helps confirm the diagnosis. The pathogenic mechanisms of endometriosis in extrapelvic sites are numerous and controversial. The theory of direct extension proposes that there is direct invasion of the endometrial tissue through the uterine musculature. (1) Menstrual flow regurgitated through the fallopian tubes into the peritoneal cavity becoming implanted on the surface of pelvic organs is another proposed theory. (2) Endometrial glands and stromal tissue spreading through venous channels and along lymphatics has also been described. (3) The theory of coelomic metaplasia involves metaplasia of cells lining the pelvic peritoneum resulting in endometriosis. (1) A combination of implantation, vascular and lymphatic metastases, direct extension, and coelomic metaplasia is referred to as the composite theory of the histogenesis of endometriosis. (4)

An increase in serum cancer antigen 19-9 concentration was found in patients with endometriosis. (5)

Because it is so extremely rare, the diagnosis and treatment of endometriosis at unusual sites remains rather difficult. In conclusion, we would like to emphasize that in a woman of childbearing age, a cystic lesion in the pancreas must have endometriosis in the differential diagnosis.

Argue for your limitations, and sure enough they're yours.
--Richard Bach

Accepted March 11, 2004.

References

1. Craig AW. Current concepts in the pathogenesis of endometriosis. Clin Obstet Gynecol 1999;42:566-685.

2. Sampson J. Peritoneal endometriosis due to the menstrual dissemination of endometrial tissue into the peritoneal cavity. Am J Obstet Gynecol 1927;14:422-469.

3. Sampson JA. Metastatic or embolic endometriosis due to menstrual dissemination of endometrial tissue into the venous circulation. Am J Pathol 1927;3:93-110.

4. Javert CJ. Pathogenesis of endometriosis based on endometrial homeoplasia, direct extension, exfoliation and implantation, lymphatic and hematogenous metastasis, including five case reports of endometrial tissue in pelvic lymph nodes. Cancer 1949;2:399-410.

5. Takemori M, Sugimura K. Ovarian chocolate cyst with markedly elevated serum CA 19-9 level: a case report. Eur J Obstet Gynecol Reprod Biol 1991;42:241-244.

RELATED ARTICLE: Key Points

* Endometriosis involving the pancreas is an extremely rare condition.

* The pathogenic mechanisms of endometriosis in extrapelvic sites are numerous.

* Histopathological demonstration of endometrial tissue in the mass helps confirm the diagnosis.

* In a woman of childbearing age with intermittent abdominal pain and a cystic lesion in the pancreas on imaging studies, endometriosis must be considered in the differential diagnosis.

Anuradha Tunuguntla, MD, Nancy Van Buren, MD, Mack R. Mathews, MD, and John A. Ehrenfried, MD

From the Department of Internal Medicine, East Tennessee State University, Johnson City, TN, and the Departments of Pathology, Medical Oncology/Hematology, and Surgical Oncology, Holston Valley Hospital Medical Center, Kingsport, TN.

Reprint requests to John A. Ehrenfried, MD, Surgical Associates of Kingsport, 914 Broad Street, Suite 2A, Kingsport, TN 37660. Email: [e-mail]