Vulvar squamous cell carcinoma in a mare - case reportABSTRACT
The present case report describes a mare diagnosed with vulvar and vaginal squamous cell carcinoma, highlighting its clinical progression, surgical management, complications and short-term recurrence. A 20-year-old Mangalarga Mineira mare, rescued in poor condition, presented with a large ulcerated vulvar mass associated with severe anemia (hematocrit 22%), weight loss, apathy and serosanguinous discharge. After stabilization with blood transfusion, fluids, nutritional support and treatment for anaplasmosis and parasitism, the animal underwent wide excision of the tumor under local and epidural anesthesia. The resected mass measured 2kg, with deep infiltration into the dorsal vulvar commissure. A second transfusion was required due to intraoperative hemorrhage. Histopathology confirmed moderately differentiated squamous cell carcinoma with marked pleomorphism, keratin pearls, vascular invasion and approximately 30% necrosis. Postoperative evolution was satisfactory, with progressive improvement in appetite, weight (from 215kg to 230kg at discharge and later 315kg) and healing of the surgical site. Two months later, local recurrence was identified, measuring 8x5cm, and a second surgery was performed. This case demonstrates the locally invasive and recurrent nature of genital squamous cell carcinoma in mares, reinforcing the importance of early diagnosis, wide excision when anatomically feasible and continuous postoperative monitoring.
Keywords:
squamous cell carcinoma; lower genital tract; equine; vulvar neoplasia; tumor recurrence
RESUMO
O presente relato de caso descreve uma égua diagnosticada com carcinoma de células escamosas vulvar e vaginal, destacando sua progressão clínica, manejo cirúrgico, complicações e recidiva em curto prazo. Uma égua Mangalarga Mineira de 20 anos, resgatada em condições precárias, apresentou uma grande massa vulvar ulcerada associada a anemia severa (hematócrito 22%), perda de peso, apatia e secreção serossanguinolenta. Após estabilização clínica com transfusão sanguínea, fluidos, suporte nutricional e tratamento para anaplasmose e parasitismo, o animal foi submetido à ampla excisão do tumor sob anestesia local e peridural. A massa ressecada pesou 2 kg, com infiltração profunda na comissura dorsal da vulva. Uma segunda transfusão foi necessária devido à hemorragia intraoperatória. A histopatologia confirmou carcinoma de células escamosas moderadamente diferenciado, com pleomorfismo marcado, pérolas de queratina, invasão vascular e aproximadamente 30% de necrose. A evolução pós-operatória foi satisfatória, com melhora progressiva do apetite, ganho de peso (de 215 kg para 230 kg na alta e posteriormente 315 kg) e cicatrização do sítio cirúrgico. Dois meses depois, identificou-se recidiva local, medindo 8x5 cm, e realizou-se uma segunda cirurgia. Este caso demonstra a natureza localmente invasiva e recorrente do carcinoma de células escamosas genital em éguas, reforçando a importância do diagnóstico precoce, excisão ampla quando possível e monitoramento contínuo pós-operatório.
Palavras-chave:
carcinoma de células escamosas; trato genital inferior; equinos; neoplasia vulvar; recidiva tumoral
INTRODUCTION
Tumors affecting the lower genital tract of mares are considered uncommon in clinical practice but hold significant relevance due to their locally invasive behavior, the frequent delay in diagnosis, and the therapeutic challenges associated with their management. Among these neoplasms, squamous cell carcinoma (SCC) stands out as the most frequently reported type in equines, although its occurrence in the vulva and vagina remains rarerare (Knottenbelt and Pascoe, 2019; Valentine, 2020; Villiers and Dobson, 2022). The typically insidious progression, combined with progressive ulceration and anatomic alterations of the perineal region, contributes to delayed clinical recognition and compromises both reproductive and urinary functions.
The anatomical configuration of the vulvar region, along with chronic irritation, microtraumas, and persistent inflammatory processes, are recognized as predisposing factors that may facilitate epithelial transformation and support the infiltrative behavior of this tumor (Knottenbelt and Pascoe, 2019; Silva et al., 2024; Yamashita-Kawanishi et al., 2021). Despite its generally low metastatic rate, genital SCC exhibits a high frequency of local recurrence, particularly when wide surgical margins cannot be achieved due to anatomical constraints (Valentine, 2020).
Given the low prevalence but notable clinical impact of such cases, case reports play an essential role in improving early recognition, therapeutic planning, and prognostic expectations for these conditions. Therefore, the aim of the present report is to describe a case of vulvar and vaginal squamous cell carcinoma in a rescued Mangalarga Mineira mare, detailing the clinical findings, preoperative stabilization, surgical management, postoperative course, and the short-term recurrence of the tumor.
ETHICAL ASPECTS
This research was not submitted to the Ethics Committee on Animal Use, as it concerns a clinical veterinary case report of routine care.
CASUISTRY
A Mangalarga Mineira mare, approximately 20 years old, was presented after being rescued from a situation of neglect. The animal showed a poor body condition (score 2/5), pale mucous membranes, apathy, and marked weight loss. During the initial clinical examination, a large ulcerated vulvar mass was observed, reddish in color, with hemorrhagic areas and serosanguineous discharge, causing discomfort and urinary difficulty. The estimated initial body weight was 215kg.
Laboratory tests revealed marked normocytic normochromic anemia (hematocrit 22%), mild hypoproteinemia, moderate hypoalbuminemia, and mild leukocytosis. Hematological evaluation also confirmed anaplasmosis, in addition to parasitism and urinary tract infection. Due to the severity of the anemia, an emergency blood transfusion was performed, increasing the hematocrit to 28%.
After clinical stabilization with fluid therapy, vitamin-mineral supplementation, antiparasitic treatment, and therapy for anaplasmosis, the mare underwent wide surgical excision of the tumor mass on September 27, 2024, under local and epidural anesthesia. The lesion weighed approximately 2kg and had an irregular surface, marked vascularization, and deep infiltration involving the dorsal commissure and cranial portion of the vaginal mucosa. Significant intraoperative hemorrhage occurred, requiring an additional blood transfusion in the immediate postoperative period. Reconstructive vulvoplasty was performed following hemostasis.
The excised tissue was submitted for histopathological analysis, which confirmed a moderately differentiated squamous cell carcinoma, characterized by marked pleomorphism, keratin pearl formation, approximately 30% necrosis, and evident vascular invasion. Postoperatively, the mare showed progressive improvement in general condition, return of appetite, adequate wound epithelialization, and weight gain (230kg at discharge).
Two months later, a local recurrence measuring approximately 8×5cm was detected, presenting rapid growth, ulceration, and infiltration. A second surgical intervention was performed on January 13, 2025, following the same anesthetic protocol and reconstructive technique. The initial postoperative course was satisfactory, and the patient remained under continuous monitoring.
RESULTS
At admission, the mare presented a compromised body condition, pale mucous membranes, apathy, and a large ulcerated vulvar mass with serosanguineous discharge (Fig. 1). Laboratory findings indicated marked anemia (hematocrit 22%), hemoglobin of 7.4g/dL, mild hypoproteinemia, moderate hypoalbuminemia, and mild leukocytosis (Table 1). Following an emergency blood transfusion, the hematocrit increased to 28%, allowing the surgical procedure to be performed.
Lateral view of the animal showing severe cachexia, depigmentation, and voluminous tumor mass in the vulvar region.
The excised tumor mass weighed approximately 2kg and exhibited an irregular surface, hemorrhagic areas, and deep infiltration into the dorsal vulvar commissure and cranial vaginal mucosa. Estimated intraoperative blood loss was 1.2L, requiring an additional transfusion immediately after surgery. Anatomical reconstruction was achieved through vulvoplasty, with satisfactory tissue adaptation.
Histopathological evaluation confirmed a moderately differentiated squamous cell carcinoma, characterized by marked pleomorphism, 138 mitotic figures per 2.37mm², approximately 30% necrosis, and evident vascular invasion. Surgical margins displayed neoplastic infiltration.
Postoperatively, the mare showed progressive improvement in overall condition, regained appetite, exhibited adequate wound epithelialization, and gained weight, reaching 230kg at hospital discharge. During the two-month follow-up, clinical parameters remained stable until a local recurrence measuring approximately 8×5cm, ulcerated and infiltrative, was detected. Biopsy confirmed recurrent squamous cell carcinoma. A second surgical excision was performed, with an initially satisfactory postoperative course.
DISCUSSION
Genital squamous cell carcinoma (SCC) in mares exhibits locally aggressive behavior, consistent with the pattern observed in this case, in which the tumor demonstrated deep infiltration and marked vascularization (Knottenbelt and Pascoe, 2019). The initial clinical presentation, characterized by severe anemia and weight loss, reflects the systemic impact resulting from both chronic inflammation and blood loss associated with tumor ulceration, a condition described in ulcerated equine neoplasms (Reed, Bayly and Sellon, 2018). The need for successive transfusions before and after excision further confirms the degree of hemodynamic compromise imposed by the lesion. imposed by the lesion. Similar invasive behavior and systemic compromise have also been described in SCC affecting other anatomical regions in horses (Chacur, 2014).
The high mitotic count, marked pleomorphism, extensive necrosis, and evidence of vascular invasion observed on histopathological examination are also consistent with more aggressive tumor behavior, according to the diagnostic criteria for moderately differentiated SCC (Meuten, 2020). These findings, combined with the anatomical impossibility of achieving wide surgical margins, contributed to the early recurrence, an outcome frequently reported in SCCs of the vulva and vagina due to restricted space and the proximity of essential functional structures (Perereira et al., 2018; Valentine, 2020).
The postoperative clinical course was favorable, with clear improvement in overall condition and weight gain, demonstrating that surgical intervention-even in advanced cases-can provide significant enhancement in quality of life (Auer and Stick, 2019). However, the short-term recurrence highlights the importance of continuous monitoring and consideration of adjunctive therapies when available, particularly in rescued animals or those with a history of delayed diagnosis (Omara-Opyene et al., 1985; Pereira et al., 2018; Diretrizes, 2019).
This case reinforces that the prognosis of genital SCC in mares depends primarily on the depth of tumor infiltration, the animal’s body condition at diagnosis, the feasibility of achieving adequate surgical margins, and rigorous postoperative follow-up.
CONCLUSION
Surgical excision of the lesion provided immediate clinical stabilization and significant improvement in the mare’s overall condition, demonstrating that intervention is effective in promoting comfort and restoring basic functions even in advanced cases of genital squamous cell carcinoma. However, the deep infiltration, the impossibility of achieving wide surgical margins, and the biologically aggressive behavior of the neoplasm resulted in early recurrence, indicating a guarded prognosis. This case highlights the importance of early diagnosis and continuous monitoring for the appropriate management of this condition.
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The research data are available within the article itself.
