Metastatic appendiceal mucinous adenocarcinoma to well-differentiated diffuse mesothelioma of the peritoneal cavity: a mimicker of florid mesothelial hyperplasia in association with neoplasms
Saturday, August 30th, 2008.
International Journal of Gynecological Pathology. 2008 Oct;27(4):526-30. [Link]
Tran TA, Holloway RW, Finkler NJ.
Department of Pathology, Florida Hospital Orlando, Orlando, Florida 32803, USA. trannguyentienanh@hotmail.com
Abstract
Atypical/florid mesothelial hyperplasia associated with another neoplastic process is not an infrequent phenomenon and has been reported in a variety of tumors. In those instances, the mesothelial proliferation might create a misdiagnosis of metastatic carcinoma but seldom raises the possibility of a well-differentiated mesothelioma seeded by metastatic neoplastic cells. Herein, we report the case of a 40-year-old woman originally diagnosed with exuberant atypical mesothelial hyperplasia after an diagnostic laparoscopy. The subsequent operation, however, demonstrated a mucinous neoplasm of the appendix with involvement of the peritoneal cavity in the form of peritoneal mucinous carcinomatosis as well as metastases to the uterine serosa and adnexal surfaces. Microscopic analysis revealed an appendiceal adenocarcinoma with signet-ring-cell features that has metastasized to a diffuse well-differentiated mesothelioma of the peritoneal cavity. In many areas, the atypical mesothelial proliferation is indistinguishable from florid mesothelial hyperplasia. The true nature of the mesothelial proliferation was only confirmed after extensive additional sampling, which showed unequivocal stromal invasion. To the best of our knowledge, this is the first report of a metastatic appendiceal mucinous adenocarcinoma to a well-differentiated diffuse mesothelioma of the peritoneal cavity. Although commonly associated with atypical/ florid mesothelial hyperplasia, a carcinoma can rarely metastasize to a well-differentiated mesothelioma, which can pose significant diagnostic difficulties because it can mimic a reactive process. This unusual case report expands the spectrum of mesothelial proliferation in conjunction with a malignant neoplasm and serves to remind pathologists that such a concomitant occurrence exists.
Glossary
- adenocarcinoma
- (add-en-o car-sin-o-muh). Cancer that starts in the glandular tissue, such as in the ducts or lobules of the breast.
- neoplasm
- (nee-o-plas-um) an abnormal growth (tumor) that starts from a single altered cell; a neoplasm may be benign or malignant. Cancer is a malignant neoplasm.
- hyperplasia
- (hy-per-PLAY-zuh) too much growth of cells or tissue in a specific area, such as the lining of the breast ducts or the prostate. By itself, hyperplasia is not cancerous, but when there is a lot of growth or the cells are not like normal cells, the risk of cancer developing is greater.
- cell
- the basic unit of which all living things are made. Cells replace themselves by splitting and forming new cells (mitosis). The processes that control the formation of new cells and the death of old cells are disrupted in cancer.
- carcinoma
- (car-sin-o-ma) a malignant tumor that begins in the lining layer (epithelial cells) of organs. At least 80% of all cancers are carcinomas.
- atypical
- (A-tip-uh-kul) not usual; abnormal. Often refers to the appearance of cancerous or precancerous cells. (See also hyperplasia.)
- mesothelioma
- a tumor derived from mesothelial tissue, such as the peritoneum (lining the abdomen) or pleura (lining the lungs). More on mesothelioma.
- peritoneal
- (pair-uh-tuh-nee-al) the serous membrane that lines the cavity of the abdomen. (More on Peritoneal Mesothelioma.)
