Mesenchymal proliferation with decidual-like morphology in seminal vesicles of aging mice

The Metrial Gland in the Rat and Its Similarities to Granular Cell Tumors

“…The metrial gland is a collection of pleomorphic granulated cells (which could be GMG cells and/or decidualized stromal cells) and spindle-shaped cells (which could be smooth muscle cells, fibroblasts, or endometrial stromal cells) with multinucleated cells and individual cell necrosis. These various cellular components result in a staining profile similar to that reported for granular cell tumors, as follows: decidualized endometrial stromal cells (positive for NSE, S100), smooth-muscle fibers (positive for desmin and actin), fibroblasts (positive for vimentin), NK cells (positive for Leu 7), macrophages (positive for F4/80), and lymphocytes (positive for Leu 7) (Karbe et al 2000). Since the histomorphologic and immunohistochemical staining profiles are similar between the granular cell tumors of aging rats and mice and the metrial glands of pregnant rats, a pathologist should consider a reactive metrial gland when confronted with a lesion of the nonpreganant mouse or rat uterus containing granulated cells.…”

“…Decidual-type reactions have been reported in the uterus during pseudopregnancy or exogenous estrogen administration (diethylstilbestrol or 17bestradiol) in the mouse (Dunn et al 1963;Highman et al 1980;Murphy 1961), and with physical or chemical stimulation (Finn and Keen 1963). These reactions have also been reported in the seminal vesicle and urinary bladder wall of aging male mice (Karbe 1987;Karbe et al 2000). When it develops at times other than normal pregnancy, it is referred to as a decidual reaction.…”

“…Although the metrial gland has received attention in human endocrinology, immunology, and reproductive physiology literature, the metrial gland has rarely been mentioned in the veterinary or toxicologic pathology literature (Karbe et al 2000; Nagatani et al 2001; Yoshida 1997). The four most recent reports and characterizations of granular cell tumors of the rat and mouse genital tract (1) do not mention the GMG cell or metrial gland; (2) do not discuss the GMG as a possible cell involved in the proliferative lesion; and (3) do not entertain the possibility that proliferative lesions involving granular cells could be non-neoplastic (Courtney et al 1992; Markovits et al 2000; Nyska et al 1991; Veit et al 2008).…”

Proliferative and Nonproliferative Lesions of the Rat and Mouse Urinary System

“…The pathogenesis of these lesions is still uncertain. Some similarities with lesions of the uterus and seminal vesicles have been reported, leading to the suggestion they may represent decidual-like reactions (Karbe et al 1998;Karbe 1999;Karbe et al 2000). This lesion is primarily spontaneous and strainspecific, being found most frequently in Swissderived mice.…”

“…Mesenchymal Proliferative Lesion (Figure 118): Urinary Bladder, Urethra Species: mouse Synonyms: decidual-like reaction, vegetative lesion, benign mesenchymal tumor Pathogenesis/cell of origin The cell of origin has not been clearly identified, but one suggestion is derivation from juxtacoelomic tissue contributing not only to parts of genital organs but also to mesenchymal portions of the urinary bladder near the trigone area in both genders (Karbe et al 2000)…”