Page 624 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

602 PART IV Specific Malignancies in the Small Animal Patient

and multiple tumors may occur. In one study, all pedunculated Surgical removal of extraluminal tumors also can be accom-
9
or polypoid tumors were benign; however, it is important to note plished through a dorsal episiotomy. Because these tumors are
often well encapsulated and poorly vascularized, blunt dissection
68
that definitive diagnosis requires histopathology.
VetBooks.ir dependent, as most dogs with these tumors are intact at diagno- generally removes them entirely. On rare occasions, a perineal
It has been suggested that vaginal leiomyomas may be hormone
approach or pelvic split may be required. Urethral catheterization
sis. 9,46,68 Furthermore, one study reported a recurrence rate of 0% prevents accidental damage to the urethra during tumor excision.
in dogs undergoing OHE at the time of tumor removal, whereas Malignant, infiltrative vaginal neoplasms can be addressed with
15% of dogs that were left intact experienced local recurrence. 9,68 complete vulvovaginectomy and perineal urethrostomy in carefully
Information from the few reported cases of canine clitoral car- selected cases. OHE is indicated in cases with multifocal disease
cinoma (CCC) suggests that the cytologic, histologic, and clinical because stable disease or regression may be obtained with hormone
features appear to mimic those of apocrine gland anal sac adenocar- ablation.
cinoma (AGASA). Cytologically, cells from CCC are arranged in
cohesive clusters, with what appear to be “bare” nuclei floating in Prognosis
a background of cytoplasm. Histologically, CCC is described as a
partially encapsulated epithelial neoplasm displaying three distinct For benign tumors, surgical excision and OHE are nearly always
patterns (tubular, solid, and rosette type). CCC cells consistently curative. The prognosis for malignant tumors must be considered
express CK AE1/AE3, but expression of neuroendocrine markers guarded because of high rates of local recurrence and metasta-
is more variable. In a study by Verin et al, neuron-specific eno- sis. Surgery with OHE was curative in the one feline leiomyoma
69
68
lase (NSE) was expressed in 6 of 6 CCC, whereas chromogranin reported.
A (CGA) and synaptophysin (SYN) were mildly expressed in two
of six tumors. S-100 expression was not detected in any of the References
69
tumors. Like AGASA, hypercalcemia of malignancy has been
reported, and locoregional nodal metastasis is a common finding at 1. Hayes A, Harvey HJ: Treatment of metastatic granulosa cell tumor
69
the time of diagnosis. in a dog, J Am Vet Med Assoc 174:1304–1306, 1979.
2. Sforna M, Brachelente C, Lepri E, et al.: Canine ovarian tumours: a
retrospective study of 49 cases, Vet Res Commun 27(Suppl 1):359–
History and Clinical Signs 361, 2003.
Presence of a mass protruding from the vulva is the most com- 3. Cotchin E: Canine ovarian neoplasms, Res Vet Sci 2:133–142, 1961.
mon clinical sign, although vaginal bleeding or discharge is often 4. Dow C: Ovarian abnormalities in the bitch, J Comp Pathol 70:59–
69, 1960.
noted. Other clinical signs may include dysuria, hematuria, tenes- 5. Cotchin E: Some tumours of dogs and cats of comparative veteri-
mus, constipation, excessive vulvar licking, and dystocia. 9,68 nary and human interest, Vet Rec 71:1040–1054, 1959.
Lipomas are generally slow growing but eventually impinge on 6. Brodey RS: Canine and feline neoplasia, Adv Vet Sci Comp Med
adjacent structures. These tumors can arise from the perivascular 14:309–354, 1970.
and perivaginal fat and lie within the pelvic canal and may attach 7. Bertazzolo W, Dell’Orco M, Bonfanti U, et al.: Cytological features
to the tuber ischium. All lipomas are reported to be well circum- of canine ovarian tumours: a retrospective study of 19 cases, J Small
scribed and relatively avascular. 68 Anim Pract 45:539–545, 2004.
Concurrent cystic ovaries and mammary adenocarcinoma have 8. Patnaik AK, Greenlee PG: Canine ovarian neoplasms: a clinicopath-
68
also been reported in a cat with vaginal leiomyoma. ologic study of 71 cases, including histology of 12 granulosa cell
tumors, Vet Pathol 24:509–514, 1987.
9. Herron MA: Tumors of the canine genital system, J Am Anim Hosp
Diagnostic Techniques and Workup Assoc 19:981–994, 1983.
10. Jergens AE, Knapp DW, Shaw DP: Ovarian teratoma in a bitch,
A presumptive diagnosis may be made based on patient signal- J Am Vet Med Assoc 191:81–83, 1987.
ment and tumor location, although definitive diagnosis requires 11. Elena Gorman M, Bildfell R, Seguin B. What is your diagnosis?
histopathology. Vaginal and rectal palpation, vaginoscopic exami- Peritoneal fluid from a 1-year-old female German Shepherd dog.
nation, and vaginal cytology are often the first steps performed in Malignant teratoma. Vet Clin Pathol 39: 393–394.
evaluation of vaginal and vulvar tumors. Retrograde vaginogra- 12. Gruys E, van Dijk JE: Four canine ovarian teratomas and a nonovar-
phy or urethrocystography may also be used to help delineate the ian feline teratoma, Vet Pathol 13:455–459, 1976.
extent of the mass. For some tumor types (e.g., TVT), aspiration 13. Gelberg HB, McEntee K: Feline ovarian neoplasms, Vet Pathol
22:572–576, 1985.
cytology of the tumor may be diagnostic; alternatively, incisional 14. Basaraba RJ, Kraft SL, Andrews GA, et al.: An ovarian teratoma in a
biopsy may be performed. Although most vaginal and vulvar cat, Vet Pathol 35:141–144, 1998.
tumors are benign, complete staging, including thoracic radio- 15. Stein BS: Tumors of the feline genital tract, J Am Anim Hosp Assoc
graphs and thorough abdominal ultrasound, should be considered 17:1022–1025, 1981.
in cases in which malignancy is suspected (e.g., rapidly growing, 16. Nielsen SW, Misdorp W, McEntee K: Tumours of the ovary, Bull
nonpedunculated tumors) or confirmed. World Health Organ 53:203–215, 1976.
17. Kennedy PC, Cullen JM, Edwards JF, et al.: Tumors of the Ovary In:
WHO. Histological Classification of Tumors of the Genital System of
Therapy Domestic Animals, Washington, DC, 1998, AFIP.
Surgical excision combined with OHE is the treatment of choice 18. McCluggage WG: Recent advances in immunohistochemistry in the
diagnosis of ovarian neoplasms, J Clin Pathol 53:327–334, 2000.
for most vaginal and vulvar tumors. For benign tumors, this is 19. Akihara Y, Shimoyama Y, Kawasako K, et al.: Immunohistochemical
likely curative, and wide resections are not necessary, especially if evaluation of canine ovarian tumors, J Vet Med Sci 69:703–708, 2007.
OHE is performed. Intraluminal tumors can be removed easily by 20. Riccardi E, Grieco V, Verganti S, et al.: Immunohistochemical diag-
transecting the pedicle. A dorsal episiotomy may be performed if nosis of canine ovarian epithelial and granulosa cell tumors, J Vet
needed for adequate visualization and exposure. 9,68 Diagn Invest 19:431–435, 2007.