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Case Reports
. 2023 Feb 17;13(4):710.
doi: 10.3390/ani13040710.

Clinical and Histological Findings of Male Uterus (Uterus Masculinus) in Three Dogs (2014-2018)

Giorgia Tura  1 , Giulia Ballotta  1 , Marco Cunto  1 , Massimo Orioles  2 , Giuseppe Sarli  1 , Daniele Zambelli  1
Affiliations
Case Reports

Clinical and Histological Findings of Male Uterus (Uterus Masculinus) in Three Dogs (2014-2018)

Giorgia Tura et al. Animals (Basel). .

Abstract

Data from three cases of uterus masculinus were retrieved from 2014 to 2018. Two out of three cases presented clinical signs compatible with systemic infection, as observed in bitches with pyometra. Ultrasound examination revealed a tubular fluid-filled structure with a thin irregular wall located cranially to the prostate and in continuity with the cranial part of the gland. In two cases, two other tubular fluid-filled structures were visualized in the caudal part of the abdominal cavity, ventrally to the prostate gland and urinary bladder. After surgical removal of these, histological examination revealed the presence of a uterine structure morphologically similar to the female counterpart. Various types of epithelial cell lining were found, including simple columnar, simple stratified and squamous epithelium associated with glands in the underlying stroma. Immunohistochemistry to anti-Müllerian hormone (AMH) produced a positive result on glands, while multifocal expression was found in the lining epithelium. AMH seems involved in the pathogenesis of uterus masculinus, but its role is not fully understood. Thorough clinical and ultrasonographical examinations, followed by a histological confirmation, are necessary to properly diagnose uterus masculinus in dogs.

Keywords: dog; histology; imaging ultrasound; uterus masculinus.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Transverse ultrasonographic image of uterus masculinus: (A) Black arrow points to the uterus masculinus filled with hypoechoic fluid and localized near the urinary bladder (white arrow). The wall of the uterus masculinus is isoechoic to the urinary bladder wall. (B) Uterus masculinus with a fluid-filled lumen (black arrow) originating from the cranial part of the prostate gland (white arrowhead) and extending cranially.
Figure 2
Figure 2
Gross anatomy of uterus masculinus: (A) Case number 1: The black arrow points to the normal testis. (B) Case number 2: White arrowhead points to the tubular fluid-filled structure originating from the dorso-cranial portion of the prostate gland. (C) Case number 3: White arrowhead points to the tubular fluid-filled structure originating from the dorso-cranial portion of the prostate gland. In all images, the black arrowhead points to the uterine horns, which arise from the body of the uterus masculinus (white arrow).
Figure 3
Figure 3
Uterus masculinus, histological findings: (A) Case number 3: The wall of the uterus masculinus with a three-layer appearance. Bar 200 µm. (B) Case number 2: Longitudinal section of the mucosal wall with squamous epithelium. Bar 200 µm. (C) Case number 1: Moderate lymphoplasmacytic and neutrophilic inflammation of the mucosal layer of the canine uterus masculinus. (A–C): Under 4× magnification, bar 200 µm, hematoxylin–eosin stain.
Figure 4
Figure 4
Uterus masculinus, immunohistochemical findings: (A) Case number 3: Multifocal-cytoplasmic AMH staining in the simple columnar epithelium of the uterine mucosa. Bar 100 µm. (B) Case number 2: Diffuse-negative immunolabelling of the uterine squamous epithelium and simultaneous strong glandular expression of AMH. Bar 100 µm. (C) Case number 1: Diffuse-strong glandular and epithelial AMH immunolabelling. (A–C): Under 10× magnification, bar 100 µm.
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