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Seven cases of feline vulval adenocarcinoma are reported. Follow-up information was available for 5 cats, and all but 1 of these was euthanized within 2–18 mo of diagnosis (median 9.2 mo) for reoccurrence of local disease (3 cases) and/or clinical signs consistent with metastases (3 cases). There was no relationship between histological features of the tumor and outcome.
Signalement de sept cas d’adénocarcinome vulvaire félin. Sept cas d’adénocarcinome vulvaire félin sont signalés. Des renseignements de suivi sont disponibles pour 5 chats et tous ces chats sauf 1 ont dû être euthanasiés dans une période de 2 à 18 mois après le diagnostic (médiane de 9,2 mois) pour la récurrence de la maladie locale (3 cas) et/ou des signes cliniques conformes à des métastases (3 cas). Il n’y avait aucun lien entre les caractéristiques histologiques de la tumeur et les résultats.
(Traduit par Isabelle Vallières)
Vulval carcinomas, including adenocarcinomas, transitional cell carcinomas, and squamous cell carcinomas, are rare in all species, with the exception of solar-induced squamous cell carcinomas of sheep and cattle in tropical countries (1). Adenocarcinoma of the vulva is especially rare. We found no reports of vulval adenocarcinomas in cats, but there is a single report each of a granular cell tumor (2) and of a leiomyosarcoma (3) of the vulva of cats. There is no information on the outcome of the granular cell tumor, but the leiomyosarcoma reoccurred and the cat was euthanized. Nothing else is known of the prognosis for vulval neoplasms. In dogs, there is 1 report of 4 squamous cell carcinomas and 1 adenocarcinoma (4) and 1 case of “epidermoid” carcinoma of the vulva (5). Dogs also develop carcinoma of the vagina and vestibule that may arise from the urethra (6); this is not described in cats. In general, carcinomas are locally invasive, often impossible to surgically excise, and may metastasize.
Vulval adenocarcinomas may arise from apocrine glands of the external vulval skin or from vestibular glands. Adenocarcinoma occurring in the vulval area could also theoretically represent metastatic spread from a distant site such as the mammary gland. In humans, there is debate about whether or not they may arise from ectopic breast tissue of the mammary line (7). There is no classification scheme for adenocarcinoma of the vulva in domestic animals. Cutaneous apocrine adenocarcinomas, however, are well recognized in dogs and cats (8–10); they are locally infiltrative with a low metastatic rate. They could occur in the perivulval region and would be indistinguishable from primary vulval adenocarcinoma.
Our objective was to report on 7 cases of feline vulval adeno-carcinoma in a retrospective study, and to provide some prognosis by providing follow-up information for 5 cases.
All cases were submissions to YagerBest Histological and Cytological Services, Guelph, Ontario between October 1999 and January 2008. Seven submitting practices provided both clinical and surgical information as documented in their files. All neoplasms were routinely fixed, processed, and stained with hematoxylin and eosin (H&E). Some results are provided in Table 1. Seven neutered female cats were diagnosed and confirmed as having vulval adenocarcinoma (cats 1, 3, 6, 7) or a neoplasm that was sufficiently close to the vulva to be described by the practitioner as being vulvar or perivulvar (cats 2, 4, 5) in location. Four were domestic short-haired cats (DSH) and there was 1 each of domestic long hair, domestic medium hair, and Siamese. The mean age of the cats was 13 y with a range of 8 to 17 y. In 6 cats, the biopsies were excisional. One had an incisional biopsy only (cat 7), as the neoplasm was too large to attempt excision.
The 7 neoplasms ranged in size from 3 × 5 mm to 15 × 15 mm, based either on the size reported by the practitioner or estimated from the histological section when there was no record of size. All were histologically invasive into surrounding tissue and none had encapsulation. Five were histologically ulcerated (cats 1, 3, 4, 5, 6). Those neoplasms that were ulcerated had inflammatory cells in the surrounding tissues. Histological classification was based on a single section of each mass, and as there are no established criteria for vulval adenocarcinoma, the World Health Organisation International Histological Classification for cutaneous apocrine adenocarcinomas (11) was used. There were 2 phenotypes: tubular (cats 2, 4, 5, 6) and solid (cats 1, 3, 7). The tubular types formed tubular structures that often were filled with an eosinophilic secretion and surrounded by a fibrous stroma (Figure 1). The solid types were mostly solid epithelial neoplasms with focal areas of duct or acinar differentiation. Anisokaryosis varied between 2- and 5-fold, and mitoses varied from < 1 to 7 per high power field (pHPF) (Table 1). In 1 neoplasm, the cells had a clear or foamy cytoplasm (cat 1). Three had neoplastic cells at the surgical margin (cats 1, 2, 3); 2 were solid and 1 was tubular, and there was no local reoccurrence in 2 (Table 1). No intravascular neoplasia was identified in any sample.
There was no correlation between neoplastic type, invasion, completeness of excision, presence or absence of reoccurrence, anisokaryosis, mitotic rate or any other feature with possible metastatic disease or eventual outcome, although the sample size was relatively small, and may not be representative.
Information on the subsequent outcome was available in 5 cases (cats 2, 3, 5, 6, 7). Two of the cats had additional surgery in an attempt to control reoccurring local disease (cats 3, 5). Four of these 5 cats were euthanized for neoplasia related reasons, either progressive local disease (cats 3, 5, 7) and or clinical signs that were suspected to be because of metastases including development of dyspnea and hemoptysis (cat 5), weight loss and ataxia (cat 6), and constipation and megacolon (cat 3). One remaining cat (cat 2) died of the complications of diabetes mellitus 9 mo after successful surgical removal. The median time from diagnosis of vulval adenocarcinoma to the time of euthanasia for suspected neoplastic disease was 9.2 mo (range: to 18 mo, mean: 9.6 mo). The surgeries were performed by veterinarians in practice settings and no adjunctive therapy such as radiation or chemotherapy was used. None of the cats had evidence of or a known history of mammary neoplasia. No postmortem was done on any of the cats.
All cats diagnosed with vulval adenocarcinoma were considered to have primary neoplasms of the vulva or immediately perivulval region based on clinical presentation and on the histological appearance of submitted biopsies. Those that developed in the vulval lip or wall likely arose from apocrine glands in that location. Apocrine glands are prominent at the mucocutaneous junction (unpublished observation) and some are associated with hair of the external skin of the vulva. There are also glands of the caudal vagina (12), and they are identical to cutaneous apocrine glands except in their location, and histological differentiation is not possible.
Because 4 of the 5 cats for which follow-up was available were euthanized for progressive local disease or reoccurrence of neoplasia locally, or for suspected metastatic disease, the prognosis for cats that develop vulval adenocarcinoma appears to be poor. The number of cases here is low and more cases would be required before a definitive prognosis could be given. The prognosis for adenocarcinoma of the vulva appears to be similar to that of the 2 other vulval neoplasms (granular cell tumor and leiomyosarcoma) of cats that have been reported (2,3). One had follow-up information and that cat was euthanized because of reoccurrence (3). The prognosis of vulval adenocarcinoma appears to be different from the prognosis reported for cutaneous apocrine carcinomas (8–10). The addition of aggressive local surgery and or adjunctive treatment for neoplasia by oncologists may alter this.
Neither the size of these neoplasms nor their histological features (Table 1) predicted the eventual clinical outcome. All but 1 of the animals with follow-up information developed progressive local and or systemic disease. This is despite marked variation in phenotype from well-differentiated to anaplastic, variation in nuclear size from 2- to 5-fold and variation in mitotic rate. The 3 cats for which the practitioners assumed there was metastatic disease represented more than half of the cats that had follow-up information. As is common with retrospective studies of this type, no postmortem examinations were performed to confirm the presence or absence of metastatic disease.
Any invasive neoplasm of the vulva would present a surgical challenge. Three cats in the present study had no local reoccurrence of the tumor in the post-operative period and 2 of the cats underwent more than 1 surgery in an attempt to control the local disease. Aggressive initial surgery seems justified considering the difficulty in achieving a local cure and the apparent poor long-term prognosis.
The exact pathogenesis of vulval adenocarcinomas is not known. Their occurrence in neutered animals suggests there is no influence of sex hormone in their development.
In conclusion, adenocarcinoma of the vulva of the cat is a rare disease but one which appears to result in a poor long-term survival. Practitioners should be aware that neoplasms of the vulva should be handled aggressively to at least control local disease. CVJ
Work was done at the Department of Pathobiology, Ontario Veterinary College, University of Guelph and was not supported by a grant. Reprints will not be available from the authors.
A summary of these cases appears on the Veterinary Reproductive Pathology Web site of Dr. Foster http://www.uoguelph.ca/~rfoster/repropath/repro.htm
Use of this article is limited to a single copy for personal study. Anyone interested in obtaining reprints should contact the CVMA office ( gro.vmca-amvc@nothguorbh) for additional copies or permission to use this material elsewhere.