Cystic lesions of the canine uterus have been recently reviewed [1]. Pseudo-placentational endometrial hyperplasia (PEH) is a rare lesion in which the endometrium grows in an ordinate architecture that strictly resembles the maternal placenta of the bitch. Pathogenesis is not totally understood, to date, even if a specific reactivity of portions of the endometrium to physical or infectious agents has been suggested by experimental studies of the University of Osaka [1]. Uterine-derived histamine produced by resident mast cells (MCs) has long been suspected as a key regulator in implantation and decidualization [2]. The aim of this study was to report two new cases of PEH and to assess the number of MCs in the lesion, comparing it with pregnant and non pregnant uterus at the same stage of the oestrous cycle. The genital tracts of two bitches were collected after routine ovariohysterectomy. They were in oestrus two months before and were not mated. Grossly, ovoid (2-3 cm in diameter) swellings were found in the uterine horn compatible with early pregnancies. On section, the uterine mucosa was pale red and thickened; at swelling level no foetal structures were found but a soft greyish tissue adhered to the mucosa with a cloudy fluid in the lumen. Histologically, ovaries and uterus were in a late dioestrous phase. The mucosal swellings showed an organized architecture, resembling the normal maternal decidua. The glandular, connective, spongy layers were recognized and even the compact layer (labyrinth) in a case. There were no inflammatory infiltrates with the exception of a large number of mast cells (MCs), identified for the pyramidal shape, the round nucleus and typical metachromasia when stained with Toluidine Blue. Additional 5 cases of unpregnant canine uteri (UU) at about 60 days of the oestrous cycle and 5 cases of placental sites (PS) of pregnant uteri at term were stained with Toluidine Blue to assess and compare the number and distribution of MCs. Shapiro-Wilks test was used to assess normality of data, paired t-test to compare the means of MCs in the different layers and between PEH, PS and UU. MCs were detected mainly (p<0.01) in myometrium of PEH and UU and in the connective layer of decidua of PEH and PS. There was a significant (p<0.01) increase of MCs in PEH versus PS and UU, and in PS versus UU. PEH is an enigmatic pathology of the canine uterus and especially in the complete form is extremely rare [1]. PEH seems also a good model to study placentation in this species. Presence and distribution of MCs suggest that they may promote the myometrial contraction, the formation of the decidua or pseudo-decidua and its vascularization [3] without the exclusion of their role in modulating the inflammatory status of uterus and placenta. [1] Schlafer and Gifford. Cystic endometrial hyperplasia, pseudo-placentational endometrial hyperplasia, and other cystic conditions of the canine and feline uterus. Theriogenology 70:349-58, 2008. [2] Wordinger et al. An assessment of mast-cell deficient mice (W/Wv) as a model system to study the role of histamine in implantation and deciduoma formation. J Reprod Fertil 73:451–456, 1985. [3] Woidacki et al. Mast cells rescue implantation defects caused by c-kit deficiency. Cell Death Dis 4: e462.10.1038/cddis.2012.214, 2013.

Pseudo-placentational endometrial hyperplasia in the bitch: assessment of mast cells.

Marino G
Writing – Original Draft Preparation
;
Sfacteria A
Methodology
;
Pruiti Ciarello F
Membro del Collaboration Group
;
Zanghì A
Supervision
2017-01-01

Abstract

Cystic lesions of the canine uterus have been recently reviewed [1]. Pseudo-placentational endometrial hyperplasia (PEH) is a rare lesion in which the endometrium grows in an ordinate architecture that strictly resembles the maternal placenta of the bitch. Pathogenesis is not totally understood, to date, even if a specific reactivity of portions of the endometrium to physical or infectious agents has been suggested by experimental studies of the University of Osaka [1]. Uterine-derived histamine produced by resident mast cells (MCs) has long been suspected as a key regulator in implantation and decidualization [2]. The aim of this study was to report two new cases of PEH and to assess the number of MCs in the lesion, comparing it with pregnant and non pregnant uterus at the same stage of the oestrous cycle. The genital tracts of two bitches were collected after routine ovariohysterectomy. They were in oestrus two months before and were not mated. Grossly, ovoid (2-3 cm in diameter) swellings were found in the uterine horn compatible with early pregnancies. On section, the uterine mucosa was pale red and thickened; at swelling level no foetal structures were found but a soft greyish tissue adhered to the mucosa with a cloudy fluid in the lumen. Histologically, ovaries and uterus were in a late dioestrous phase. The mucosal swellings showed an organized architecture, resembling the normal maternal decidua. The glandular, connective, spongy layers were recognized and even the compact layer (labyrinth) in a case. There were no inflammatory infiltrates with the exception of a large number of mast cells (MCs), identified for the pyramidal shape, the round nucleus and typical metachromasia when stained with Toluidine Blue. Additional 5 cases of unpregnant canine uteri (UU) at about 60 days of the oestrous cycle and 5 cases of placental sites (PS) of pregnant uteri at term were stained with Toluidine Blue to assess and compare the number and distribution of MCs. Shapiro-Wilks test was used to assess normality of data, paired t-test to compare the means of MCs in the different layers and between PEH, PS and UU. MCs were detected mainly (p<0.01) in myometrium of PEH and UU and in the connective layer of decidua of PEH and PS. There was a significant (p<0.01) increase of MCs in PEH versus PS and UU, and in PS versus UU. PEH is an enigmatic pathology of the canine uterus and especially in the complete form is extremely rare [1]. PEH seems also a good model to study placentation in this species. Presence and distribution of MCs suggest that they may promote the myometrial contraction, the formation of the decidua or pseudo-decidua and its vascularization [3] without the exclusion of their role in modulating the inflammatory status of uterus and placenta. [1] Schlafer and Gifford. Cystic endometrial hyperplasia, pseudo-placentational endometrial hyperplasia, and other cystic conditions of the canine and feline uterus. Theriogenology 70:349-58, 2008. [2] Wordinger et al. An assessment of mast-cell deficient mice (W/Wv) as a model system to study the role of histamine in implantation and deciduoma formation. J Reprod Fertil 73:451–456, 1985. [3] Woidacki et al. Mast cells rescue implantation defects caused by c-kit deficiency. Cell Death Dis 4: e462.10.1038/cddis.2012.214, 2013.
2017
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/3120677
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