CASE REPORT

Multicystic mesothelioma with endometriosis GABRIEL M. GROISMAN AND HEDWIGA KERNER From the Department of Pathology, Rambam Medical Center, Haifa, Israel

ALVUObster Gynecol Scand 1992; 71: 642-644 A multicystic mesothelioma of the omentum in a 36 year old woman consisted of a

multicystic mass with foci of typical endometriosis and ‘necrotic pseudoxanthomatous nodules’. The presence of endometriosis within multicystic mesothelioma has never been reported. Our findings support the hypothesis that endometriosis plays a r61e in the pathogencsis of multicystic mesothelioma and that this is a reactive rather than a neoplastic lesion. Key ward.7: multicystic mesothelioma; endometriosis; necrotic pseudoxanthomatous nodules Submitted April 21, 1992 Accepted May 4, 1992

Multicystic mesothelioma (MCM) also known as ‘multilocularperitoneal inclusion cyst’ (1,2) is a rare cystic mesothelial proliferation in the peritoneal cavity of young adult women. Its clinical and morphologic profile has been well defined (2,3), but controversies as to its neoplastic or reactive nature persist. We report our observations in the first case of MCM in which typical endometriosis was identified as part of the tumor. Our findings confirm that abdominal or pelvic endometriosis may predispose to MCM.

both adnexa were normal. Omentectomy and appendectomy were performed. The patient is alive and well one year after the operation.

Pathologlc findings Gross examination revealed a 23 X 20 X 7 cm cystic mass composed of multiple, smooth-surfaced, thinwalled, pink to white, translucent locules, containing

Case report A 36 year old otherwise healthy woman was admitted to the Rambam Medical Center with abdominal pain of several months duration. Ultrasonographic examination disclosed a large abdominal cystic lesion. Surgical exploration revealed a cystic mass involving the entire omentum. The uterus and

Abbreviations: MCM: multicystic mesothelioma; NPN: necrotic pseudoxanthomatous nodes @ A d a Obsrer Gynecol Scand 71 (1992)

Fig. 1. Gross view of MCM.The omenturn is transformed into a cystic mass composed of multiple thin-walled locules.

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Fig. 4. A ‘necrotic pseudoxanthomatous nodule’ at low magnification. (Hematoxylin-Eosin x 40). Fig. 2. The cysts are lined by a single layer of flattened cells. (Hematoxylin-Eosin x 300).

serous or serosanguineous fluid (Fig. 1). The individual locules varied in size from 5 mm to 5 cm. On histologic examination the lesion was composed of multiple cysts of varying size separated by variable amounts of fibroblastic stroma with acute and chronic inflammatory infiltrate. The cysts were lined by flat to cuboidal mesothelial cells without significant atypia or mitotic activity (Fig. 2). Foci of well developed endometrial glands surrounded by a cuff of endometrial stroma were situated either within the MCM stroma or adjacent to cysts (Fig. 3). In some areas, flat mesothelial cells overlayed the endometrial stroma, while in others the cyst lining was partially or totally replaced by granulation tissue, inflammatory cells and variable numbers of pseudoxanthoma cells. Several ‘necrotic pseudoxanthomatous nodules’ (4) were present within the stroma (Fig. 4). They consisted of circumscribed granulomatous nodules measuring 1 to 4 mm in diameter

Fig. 3. A focus of endometriosis (right) within the MCM. (Hematoxylin-Eosin X 125).

with central necrosis surrounded by large histiocytes (pseudoxanthoma cells), hyalinized fibrous tissue or both. The pseudoxanthoma cells had abundant cytoplasm with large amounts of fine granular pale brown cytoplasmic pigment (Fig. 5 ) . Immunostaining revealed cytokeratin in the cytoplasm of the cells lining the cysts and endometrial glands. Factor-VIII related antigen was negative. Electron microscopic examination of cells lining the cysts showed the typical features of mesothelial cells. They had numerous long, thin microvilli along their luminal surface and were connected by well formed desmosomal attachments. A well defined basal lamina separated them from a stroma composed mainly of abundant collagen fibers.

Discussion Multicystic mesothelioma (MCM) is a well recognized but rare lesion. Its mesothelial nature was

Fig. 5. Pseudoxanthoma cells showing abundant cytoplasm containing fine pigment granules. (Hematoxylin-Eosin X

250). @ Act0 Obsrer Gynecol Scand 71 (1992)

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G . M . Groisman and H. Kerner

confirmed in our and previous studies by a positive immunohistochemical reaction for cytokeratin and the presence of desmosomes, tonofilaments and slender microvilli on ultrastructural examination (1-3,5-8). The most controversial aspect of MCM is its pathogenesis. Different authors have regarded the lesion as reactive (1,2), relatively benign (9,or as low-grade malignant neoplasms (6,7). According to Katsube et al. (8) and Weiss and Tavassoli (3), MCM occupies an intermediate position in a spectrum of mesothelial neoplasms, which vary from benign adenomatoid mesothelioma to malignant mesothelioma. In contrast, Ross et al. consider MCM as part of the morphologic spectrum of reactive mesothelial proliferative lesions with previous abdominal operations, endometriosis, and pelvic inflammatory disease as risk factors (2). Endometriosis has been reported as a risk factor o r an associate operative finding of MCM (1,2, !311). The present case revealed foci of typical endometriosis within the MCM, a finding not previously reported. Transitional areas between endometriosis and mesothelial cysts were also noted. In a few areas, granulation tissue admixed with heavily pigmented pseudoxanthoma cells resembled changes described in old endometriosis (12). Pseudoxanthoma cells were also present in several ‘necrotic pseudoxanthomatous nodules’ (NPN) located within the MCM stroma. NPN were described by Clement et al. (4) as a rare manifestation of endometriosis. Pseudoxanthoma cells are regarded as histiocytes containing degradation products of blood that accumulate in the stromal component of endometriosis (4.12). Our observations lead us to the conclusion that the presence of endometriosis and NPN within MCM provides convincing evidence that reactive mesothelial inflammatory changes caused by endometriosis play a r81e in the pathogenesis of this rare mesothelial proliferation.

Mrs. Marva Barbee for typing and M. R. Dische, MD. PhD for reviewing this manuscript.

References 1. McFadden DE, Clement PB. Peritoneal inclusion cysts

with mural mesothelial proliferation: A clinicopathologic analysis of six cases. Am J Surg Pathol 1986; 10: 844-54. 2. Ross MJ, Welch WR, Scully RE. Multilocular perito-

neal inclusion cysts (so-called cystic mesotheliomas). Cancer 1989; 64: 1 3 3 U 6 . 3. Weiss SW, Tavassoli FA. Multicystic mesothelioma: An analysis of pathologic findings and biologic behavior in 37 cases. Am J Surg Pathol 1988; 12: 737-46. 4. Clement PB. Young RH. Scully RE. Necrotic pseudoxanthomatous nodules of ovary and peritoneum in endometriosis. Am J Surg Pathol 1988; 12: 3 W 7 . 5. Miles JM, Hart WR. McMahon JT. Cystic mesothelioma of the peritoneum: Report of a case with multiple recurrences and review of the literature. Clev Clin Q 1986; 53: 109-14. 6. Alvarez-Fernandez E, Rabano A. Barros-Malvar JL. 7. 8.

9. 10.

Sanabria-Valdez J. Multicystic peritoneal mesothelioma. A case report. Hispathology 1989; 14: 199-208. Villaschi S, Autelitano F, Santeusanio G. Balistreri P. Cystic mesothelioma of peritoneum. A report of three cases. Am J Clin Pathol 1990; 94: 758-61. Katsube Y, Mukai K. Silverberg SG. Cystic mesothelioma of the peritoneum: A report of five cases and review of the literature. Cancer 1982; 50: 1615-22. Jones EG, Donovan AJ. Adenomatoid tumor of the ovary versus mesothelial reaction. Am J Obstet Gynecol 1%5; 92: 694-8. Krieger JS, Fisher ER. Richards MR. Multiple mesothelial cysts of the peritoneum. Am J Surg 1952; 84:

328-30. 11. Schneider V, Partridge JR, Gutierrez F, Hurt WG,

Mazels MS, Denmay RM. Benign cystic mesothelioma involving the female genital tract: Report of four cases. Am J Obstet Gynecol 1983; 145: 355-9. 12. Clement PB. Pathology of endometriosis. Pathol Annu 1990; 25 (Pt 1): 245-95. Address for correspondence:

Acknowledgment The authors thank Ms. Y. Zoref. Mrs. S. Ben-Eliezer and Mrs. I. Reiter, MsC. for excellent technical assistance;

0 Acta Obsrrt Gynecol Scand 71 (1992)

Gabriel M.Groisman. M.D. Department of Pathology The Mount Sinai Medical Center One Gustave L. Levy Place New York, NY 10029

U.S.A.