Pleural endometriosis in an aged rhesus macaque (Macaca mulatta): a histopathologic and immunohistochemical study

Abstract

Endometriosis is defined as the presence of endometrial tissue outside the uterine cavity and is one of the most common reproductive abnormalities encountered in women as well as Old World primates. The majority of endometriosis cases in Old World primates occur within the abdominal cavity, with spread to extraabdominal sites considered to be a rare event. A 19-year-old multiparous female rhesus macaque (Macaca mulatta) presented to necropsy for difficulty breathing and weight loss. Grossly, the animal had marked abdominal endometriosis and severe hemoabdomen and hemothorax, the latter of which was accompanied by marked pleural fibrosis. Histologic examination confirmed the abdominal endometriosis and also revealed numerous uterine glands and stroma embedded within the pleural fibrosis. Rafts of endometrial tissue were present within pulmonary lymphatics and the tracheobronchial lymph nodes. Immunohistochemically, all ectopic endometrial tissue had varying degrees of positive immunoreactivity to cytokeratin, vimentin, progesterone and estrogen receptors, and calretinin but was negative for desmin and carcinoembryonic antigen. Pleural endometriosis is an extremely rare manifestation of endometriosis in nonhuman primates. This case report emphasizes lymphatic spread as a likely mechanism for extrauterine endometriosis.

Figure 1

Lung pleura; rhesus macaque. Multifocally, endometrial glands and stromal cells are embedded within the pleura. HE.

Figure 2

Lung pleura; rhesus macaque. Glands are lined by pseudostratified columnar epithelial cells that infrequently contain a mucinous secretion (inset; periodic acid Schiff). HE.

Figure 3

Lung pleura; rhesus macaque. The pleura is diffusely thickened by marked fibrosis and edema admixed with numerous hemosiderin-laden macrophages and a mixed inflammatory reaction (inset). HE.

Figure 4

Lung; rhesus macaque. Aggregates of endometrial glands are present within lymphatic vessels. HE.

Figure 5

Tracheobronchial lymph node; rhesus macaque. The lymph node capsule is thickened, and there are foci of endometriosis in the capsule (arrow). HE.

Figure 6

Tracheobronchial lymph node; rhesus macaque. Rafts of endometrial glands are present within the subcapsular sinuses of tracheobronchial lymph node (arrows). HE.

Figure 7

Pleural endometriosis, lung; rhesus macaque. Endometriotic glandular epithelium has strong immunoreactivity for cytokeratin. Immunoperoxidase staining, DAB chromogen, Mayer’s hematoxylin counterstain.

Figure 8

Endometrium; rhesus macaque. Glandular epithelial cells have strong immunoreactivity for cytokeratin. Immunoperoxidase staining, DAB chromogen, Mayer’s hematoxylin counterstain.

Figure 9

Pleural endometriosis, lung; rhesus macaque. There is strong intranuclear immunoreactivity in the endometriotic stroma and weak immunoreactivity in the epithelial cells for progesterone receptor. Immunoperoxidase staining, DAB chromogen, Mayer’s hematoxylin counterstain.

Figure 10

Endometrium; rhesus macaque. Roughly 50% of the glandular epithelial cells have strong nuclear immunoreactivity for progesterone receptor, and the stroma is negative. Immunoperoxidase staining, DAB chromogen, Mayer’s hematoxylin counterstain.

Figure 11

Pleural endometriosis, lung; rhesus macaque. There is scattered nuclear immunoreactivity for estrogen receptor in the stromal and epithelial cells of the endometriotic tissue. Immunoperoxidase staining, DAB chromogen, Mayer’s hematoxylin counterstain.

Figure 12

Endometrium; rhesus macaque. Roughly 75% of the glandular epithelial cells have strong nuclear immunoreactivity for estrogen receptor. Immunoperoxidase staining, DAB chromogen, Mayer’s hematoxylin counterstain.

Figure 13

Pleural endometriosis, lung; rhesus macaque. Endometriotic tissue has strong cytoplasmic immunoreactivity for vimentin. Immunoperoxidase staining, DAB chromogen, Mayer’s hematoxylin counterstain.

Figure 14

Endometrium; rhesus macaque. Stromal cells have strong intracytoplasmic immunoreactivity for vimentin. Immunoperoxidase staining, DAB chromogen, Mayer’s hematoxylin counterstain.

Figure 15

Pleural endometriosis, lung; rhesus macaque. Rare calretinin immunoreactive cells are present in the endometriotic stroma. Immunoperoxidase staining, DAB chromogen, Mayer’s hematoxylin counterstain.

Figure 16

Endometrium; rhesus macaque. Roughly 50% of stromal cells have strong cytoplasmic immunoreactivity for calretinin. Immunoperoxidase staining, DAB chromogen, Mayer’s hematoxylin counterstain.