REMAINING UTERINE MESONEPHRIC DUCT CYST IN FEMALE DOG (CANIS FAMILIARIS)--FIRST CASE REPORT IN BRAZIL/CISTO DE DUCTO MESONEFRICO UTERINO REMANESCENTE EM CADELA (CANIS FAMILIARIS)--PRIMEIRO RELATO DE CASO NO BRASIL/QUISTE REMANECIENTE DEL DUCTO MESONEFRICO UTERINO EN PERRA (CANIS FAMILIARIS)--PRIMERO RELATO DEL CASO EN BRASIL.
During conversion process of urogenital system in primary postnatal functional system, some organs and/or ducts are degenerate and consequently reabsorbed (2). However, they can be completely reabsorbed before or immediately after birth or may remain as vestigial form (2,3). This forms can be replaced by a cystic structure along the urogenital system or retroperitoneal region and/or pelvic cavity (1,3,4).
Remaining uterine mesonephric duct cyst (RUMDC) and secondary manifestations in dogs are lack in literature. Default documented reports over RUMDC in dogs can lead to incorrect diagnosis due to its histopathologycal similarity to other conditions, as neoplasia. The present work aims to describe the first documented case report about remaining uterine mesonephric duct cyst and secondary manifestations in female Pinscher dog, with 8 years old.
A female Pinscher dog, with 8-year-old, 3 kg, non spayed, was presented to the private practice, Sao Paulo, Brazil for a check-up. The dog never had puppies and owner reported no heat at last 18 months. No other physiological alterations were reported. Vaccination and deworming were updated. During clinical examination, cysts were observed in teats of both mammary chain (Figure 1) and without vaginal discharge.
The haemogram, serum biochemistry and urinalysis were normal. The abdominal ultrasound and thorax X ray did not showed any alteration. Thus, the teats were submitted to fine needle aspiration cytology. Cytopathologic examination revealed active macrophages, rare neutrophilus and mesenchymal cells, and homogeneous blue material. Cytological evidence of malignancy was not observed. The cytological findings were consistent with cystic lesion without evidence of malignancy.
Therefore, was performed an ovaryhysterectomy and identified endometrial hyperplasia and slight presence of purulent material on the right uterine horn. Ovaries and uterus were submitted to histopathologycal examination with hematoxiline-eosine (HE). Uterus histopathologycal examination showed endometrial with prismatic and cuboid cells, with acidophilic and eventually vacuolated cytoplasm. Endometrial glands identified tubules with acidophilic material and sometimes dilated and formed small cysts. Cysts were observed in the uterus, delineated by layers of smooth muscle and cuboid cells (Figure 2). There were no alterations regarding the ovaries.
The histopathologycal findings were consistent with remaining uterine mesonephric duct cyst associated with slight endometrial hyperplasia. Was prescribed enrofloxacin (1 mg/kg PO, SID, 10 days) and carprofen (2.2 mg/kg PO, BID, 5 days). Twenty-four hours after surgery, cystic of teats disappeared and skin sutures were removed 7 days after. Clinical examination, haemogram, serum biochemistry, urinalysis, abdominal ultrasound and thorax X-ray were performed at two different moments after surgery, 10 days and 6 months, respectively, and no changes were observed in any of moments.
The present case reported the remaining uterine mesonephric duct cyst in female dog. Apparently, there are no data in the literature about the RUMDC in dogs and can be the first case documented in Brazil. Several urogenital disorders associated with paramesonephric and mesonephric ducts have been described in humans and other mammals by several authors (13,5), but none in dog uterus. Disorders associated with mesonephric duct are commonly diagnosed as neoplasia and may thus had contributed to poor documentation regarding this condition in dogs (4,6-9). On the other hand, the RUMDC is diagnosed accidentally during histopathologycal examination (6), and may also contribute to lack reports.
In the canine female is common to diagnostic the Gartner ducts or cysts that is originating from mesonephric duct remnants which can affect in fertility and health (10). Are more frequently referred to in bitches and can be persist close to the myometrium and the uterine horns (11,12).
The diagnostic of RUMDC was by histopathologycal examination, similar with literature (4,6,7). Ovarian cysts in cattle, pigs and rodents, often secrete high quantity of estrogens, which can cause irregular estrous cycles, persistent estrus and infertility (8,9,13).
According to Bartel et al. (10), cases of Gartner cysts originating from mesonephric duct remnant the ectopic endometrium was characterized by immunohistochemistry (oestrogen and progesterone receptors, proliferation activity, cytokeratin, alpha smooth muscle actin, and vimentin) and lectin histochemistry. In this cases, can be observed hypertrophic cells at the serosal (positive reactions to anti-oestrogen receptor and anti-cytokeratin immunohistochemistry) site of the uteri and in all mesonephric remnants, surface and glandular epithelial cells of the ectopic endometrium gave positive immunoreactions for cytokeratin, oestrogen and progesterone receptors (10). On the other hand, muscle actin and vimentin positive can be identified on the stromal cells of the ectopic endometrial (10).
The immunohistochemical characterization of canine mesonephric remnants is slight accessible in Veterinary Medicine, especially in private laboratories, for different reasons, including absence of reagents and pricey. Since histopathologycal changes were observed in both ovaries, it was supposed that cystic structures located in teats and irregular estrus were secondary manifestations to RUMDC, because the cystic lesions disappeared after ovaryhysterectomy. The mesonephric remnants of the mesosalpinx is characterized as a simple tubular structures lined by low columnar to cuboidal cells sometimes featuring cilia with proteinaceous fluid lumina (13).
The correct diagnosis of RUMDC is crucial because can be confused with neoplasia or another similar condition. Cysts on teats and irregular estrus were associated with RUMDC, and ovaryhysterectomy is an option to treat this condition in dogs.
Recebido em: 02/02/2015
Aceito em: 30/03/2017
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Ivan F. Charas Santos 
Maira Duarte Del Poente 
Bruna Brancalion 
Bruna Martins Silva 
Mayara Viana Freire Gomes 
Frederico Matheus Ducatti Gois 
Diana Milanez Avila Dias Maciel 
 Universidade Estadual Paulista-Faculdade de Medicina Veterinaria e Zootecnia. Botucatu, SP. Brasil. Universidade Eduardo Mondlane. Faculdade de Veterinaria. Maouto, Mocambique. Contato principal para correspondencia.
 Medica Veterinaria Autonoma. Sao Paulo
 Graduanda em Medicina Veterinaria. Faculdade de Medicina Veterinaria e Zootecnia. UNESP. Botucatu
Caption: Figure 1. Female Pinscher dog, 8-year-old, showing cysts in teats of both mammary chain (white arrows) (Ivan Santos).
Caption: Figure 2. Photomicrography of female Pinscher dog, 8-year-old, diagnosed with remaining uterine mesonephric duct cyst. END--Endometrium with prismatic and cuboid cells, with acidophilic and eventually vacuolated cytoplasm. GE--Endometrial glands. CIS--Cyst with acidophilic material delineated by layers of smooth muscle and cuboid cells. HEM--Hemorrhage. (HE. 40x) [Bar:100 [micro]m] (Ivan Santos).