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Can Vet J. 2010 December; 51(12): 1387–1390.
PMCID: PMC2978993

Language: | French

Urogenital leiomyosarcoma in an alpaca

Abstract

A mass in the pelvic canal of a 4-year-old pregnant alpaca hembra diagnosed as leiomyosarcoma of the urogenital tract was confirmed by biopsy. Following a tube cystotomy, the alpaca was presented 33 d later, 2 d after the tube cystotomy had been dislodged. A dead cria was delivered by caesarean section.

Résumé

Leiomyosarcome génito-urinaire chez un alpaca. Une masse dans le canal pelvien d’une femelle alpaca gravide âgée de 4 ans est diagnostiquée comme un leiomyosarcome du tractus génito-urinaire, ce qui a été confirmé par biopsie. Après une cystotomie par tube, l’alpaca a été présenté 33 jours plus tard, 2 jours après le déplacement du tube de cystotomie. Un cria mort-né a été accouché par césarienne.

(Traduit par Isabelle Vallières)

A multiparous 4-year-old alpaca hembra was presented to the University of Wisconsin Veterinary Medical Teaching hospital for evaluation of stranguria of 2 to 3 wk duration and hematuria for 1 d. A mass within the pelvic canal was detected on examination per rectum by the referring veterinarian on the day of presentation.

Case description

The hembra was 277 d pregnant and had a body condition score of 3/5. On physical examination the animal was bright, alert and responsive, and vital signs were within normal limits. There was a significant amount of clotted blood around the perineum and adherent to the fiber on the hind limbs. The alpaca postured to urinate frequently, producing only small volumes of urine intermittently. Vaginoscopy revealed a multinodular mass involving the ventral and lateral vaginal walls of the middle vagina, extending from the urethral opening in a cranial direction. The mass was poorly visualized due to the marked hemorrhage, the source of which was not identified. The caudal aspect of the mass did not appear ulcerated. Vaginal ultrasound showed a 4.5 × 6 × 3 cm mixed echogenic mass, and a tightly distended bladder, with hyperechoic material on the floor. Transabdominal ultrasound confirmed fetal viability (fetal heart rate 92 beats/min). A 10 French Foley urinary catheter was placed with some difficulty, due to the mass obscuring the urethral opening, and approximately 600 mL of blood-tinged urine was obtained. Urinalysis revealed a urine packed cell volume (PCV) of 12% and proteinuria (+4). The urinary catheter was sutured to the lateral aspect of the left vulvar lip; however, due to the persistent straining, it could not be maintained in position.

A Tru-cut biopsy of the mass was performed and cytology of an impression smear showed a pleomorphic population of large spindle-shaped mesenchymal cells with oval to thin, elongate nuclei. Cytologic findings were interpreted as consistent with a sarcoma such as leoimyosarcoma or fibrosarcoma. Histopathology of the biopsy sample showed interwoven streams and bundles of elongated spindle-shaped mesenchymal cells with abundant eosinophilic cytoplasm and oval to elongated nuclei. Smooth muscle actin immunohistochemistry was positive, and a diagnosis of presumptive leiomyoma or well-differentiated leiomyosarcoma was provided. Complete blood (cell) count and plasma biochemistry profiles were unremarkable. The mass was considered inoperable, with little possibility of a complete resection or sufficient debulking to provide an adequate opening to the urethra, for unobstructed urination. A tube cystotomy was recommended and performed as a salvage procedure, in an attempt to allow fetal development to a viable state, or a minimum of 321 d of gestation. Antibiotic therapy was instituted pre-operatively and maintained for 3 d after surgery: potassium penicillin (Pfizerpen; Roerig, New York, New York, USA), 22 000 IU/kg body weight (BW), IV, QID and ceftiofur (Naxel; Pharmacia and Upjohn Company, New York, New York, USA), 2.2 mg/kg BW, IV, BID. Anti-inflammatory therapy was instituted with phenylbutazone (Phenylbutazone paste; Schering-Plough Animal Health, Union, New Jersey, USA), 2 mg/kg BW, PO, SID, and continued for 30 d.

On day 2 following admission, the animal was restrained in dorsal recumbency under general anesthesia for placement of a tube cystotomy. A ventral midline celiotomy was performed in the caudal abdomen. The incision started 5 cm caudal to the umbilicus and extended caudally, between the mammary glands, to the brim of the pelvis. This permitted visualization, but not exteriorization of the apex of the grossly distended bladder. Urine was aspirated with suction applied through an 18-gauge × 3.75-cm needle. Stay sutures of 2-0 polypropylene were positioned through the medial and lateral aspects of the apex. No abnormalities were visualized or palpated within the bladder wall. A stab incision was made through the skin, approximately 5 cm to the right of midline, level with the fold of the flank. Carmalt clamps were used to undermine the tissues in a caudo-medial direction, creating a tunnel approximately 20 cm long. Immediately cranial to the brim of the pelvis, the rectus abdominis muscle and peritoneum were penetrated, to permit entry into the celomic cavity.

A 16 French Foley catheter was then passed through the tract and inserted into the bladder through a stab incision made through wall, between the stay sutures, at the cranio-ventral aspect of the apex. The 10-mL balloon was inflated with sterile saline and the opening in the bladder closed with purse-string suture of 2-0 polygalactin 910 (Vicryl; Ethicon, San Angelo, Texas, USA). Gentle traction was applied to the catheter in an attempt to bring the bladder into close proximity with the body wall. Approximately 5 cm of Foley catheter remained exposed within the celomic cavity. The abdomen was copiously lavaged with sterile poly-ionic fluids, prior to routine closure of the incision. A Chinese finger trap suture was placed through the skin around the drain, to fix it in position. Following surgery, the tube cystotomy catheter was flushed with saline to confirm patency. Then the finger of a rubber glove with a small opening created in the tip was applied to the end of the Foley catheter to act as a one-way valve. The alpaca recovered uneventfully from the anesthetic, and was able to pass urine through the catheter. She was discharged from the hospital 5 d after admission.

Thirty-three days after initial examination, at day 310 of pregnancy, the hembra was represented to the hospital as the Foley catheter used for the tube cystotomy had been dislodged 2 d previously. Urine was seen dripping from the vulva and the alpaca had been straining to defecate and urinate for 4 d. Vital signs remained within normal limits; however, the alpaca had lost 23 kg BW (27%) and now had a body condition score of 1/5, despite a ravenous appetite. Abdominal ultrasound examination was unremarkable, with no free fluid detected within the peritoneal cavity. Vaginal examination with endoscopy, ultrasound and digital palpation showed a remarkable increase in the size of the neoplasm, along with massively engorged vaginal vasculature. Transabdominal ultrasound confirmed fetal viability (fetal heart rate 84 beats/min). The urinary bladder could not be identified, thought to be due to the size of both the mass and the cria. Urinary bladder catheterization per vagina was thought to be successful. Approximately 18 h after presentation, the alpaca went into second stage labor with fetal membranes protruding from the vulva lips and a leg of the cria in the caudal vagina. The hembra was anesthetized and a caesarean section produced a non-viable, 4.1-kg cria, which was markedly dysmature, with no hair growth and soft gelatinous hooves. Necropsy of the cria was consistent with in utero fetal death. The hembra was euthanized following delivery of the cria.

Necropsy of the hembra revealed a 10 × 6 × 6 cm irregular, multinodular transmural mass in the wall of the cranial vagina that protruded into the lumen. The luminal surface and center of the mass were necrotic, with the tissue mass replaced by inspissated, white to tan mottled red caseous material. Small tendrils of the neoplasm extended from the mass into the surrounding tissues. The urinary catheter was found to have penetrated the caudal aspect of the mass in the center of the necrotic area, and subsequently entered the peritoneal cavity. There was a mild to moderate amount of fibrin lightly adherent to many serosal surfaces and there were fibrinous adhesions throughout the abdominal cavity. Bilaterally, the renal cortices had myriad generalized, 1 to 3 mm diameter, white foci that often extended from the corticomedullary junction to the capsular surface. The bladder was small and shrunken, contained no urine and was filled with inspissated, white, caseous material that extended into the neck.

On histopathologic examination, the vaginal mass was unencapsulated and invasive, composed of broad interlacing streams and bundles of elongated spindle-shaped cells with variably distinct borders and abundant amounts of eosinophilic cytoplasm. Nuclei were oval to elongated, often with blunt ends, and had finely stippled chromatin with 1 to 3 variably sized round to oval nucleoli. Mitotic figures were common at 4 to 6 per 400× field with frequent bizarre forms, and aniskaryosis was marked. The luminal surface of the mass was diffusely necrotic and covered in a fibrinosuppurative exudate with myriad mixed bacteria. A sublumbar lymph node also contained similar neoplastic cells, with a higher degree of anisokaryosis and nuclear pleomorphism. On immunohistochemistry, neoplastic cells of both the primary and the metastatic masses showed strongly positive cytoplasmic immunoreactivity for vimentin and desmin. Most neoplastic cells showed positive cytoplasmic immunoreactivity for smooth muscle actin; however, labeling was overall less intense than internal controls of normal vaginal smooth muscle and vascular wall smooth muscle cells. A diagnosis of vaginal leimyosarcoma with metastasis to a regional lymph node was made. Additional histologic diagnoses included severe chronic necrosuppurative cystitis with intralesional mixed bacteria, severe multifocal chronic suppurative tubulointerstitial pyelonephritis with intralesional gram-negative bacteria and moderate, multifocal subacute to chronic fibrinosuppurative peritonitis.

Discussion

Leiomyosarcoma is an uncommon soft tissue tumor reported in humans and animals (1,2). Usually these neoplasms originate in areas of abundant smooth muscle such as the gastrointestinal or urogenital tract. To the authors’ knowledge, leiomyosarcoma has not been reported in South American camelids. Neoplasia, however, has been frequently reported in camelids with prevalence in a group presented for necropsy in one study reported to be 6.9% (3). Neoplasia of the urogenital tract has been reported in this species and includes lymphoma (4), nephroblastoma (5), ovarian interstitial cell tumor (6), urethral sarcoma (7), and renal teratoma (8). It was not possible to determine whether the tumor originated from the urethral or vaginal smooth muscle due to the advanced state of the neoplasia on initial presentation and necropsy.

The clinical symptoms in this case were similar to those in other species with stranguria and vaginal bleeding. Leiomyosarcoma has been associated with a number of risk factors in women, including multiparous, ionizing radiation exposure, chemical herbicides, and hormonal influences (2). The importance of such factors in this species can not be elucidated in this single case report. The alpaca in this case report, however, was multiparous, and had similar clinical signs to those reported in women with vaginal leiomyosarcoma. Little is known about the clinical progression or biological behavior of leiomyosarcomas in large animal species because of the low frequency with which these tumors have been described. The neoplasm in this case was locally invasive and metastasized to a local lymph node, which is typical of this type of tumor in humans (2). Recently, chemotherapy was unsuccessful in the treatment of urogenital leiomyosarcoma in a horse (9). In human oncology, treatment of vaginal leiomyosarcomas involves surgical excision, or debulking, and radiation therapy (10). Surgical resection was not attempted in this animal due to poor surgical access and little prospect of being able to debulk the mass with wide margins and create a patent urethra. Radiation therapy was not considered in a pregnant animal, however, palliative care was attempted to maintain the pregnancy to a stage where a viable cria could be removed by caesarean section. Although the gestational length of alpacas is 340 to 346 d, the gestational age for viability has not been determined to the authors’ knowledge. However, in our hospital, cria’s born over 321 d of gestation are considered to have a better prognosis than those born prior to this (unpublished observation). This case highlights that even if pregnancy can be maintained in alpacas with life threatening disease, the maturation of the cria does not always proceed normally, and the fetus may not be viable even at a gestational age at which this is usually the case.

Tube cystotomy placement was challenging, due to the anatomic location of the camelid urinary bladder. While tube cystotomy was achieved, the small size of the urinary bladder as well as its relatively caudal and dorsal location within the peritoneal cavity, limited our ability to secure it to the ventral abdominal wall. This may have contributed to the development of peritonitis; however, ascending cystitis and pyelonephritis, or migration of bacteria through the necrotic tumor, may also have been the etiology of the peritonitis. Additionally, the fibrous adhesions may have developed in response to handling of the tissues during the initial surgery and fibrinous adhesions to placement of the urinary catheter through the mass into the peritoneal cavity. Bacterial migration and/or hematogenous spread from the ascending cystitis, pyelonephritis or the necrotic tumor are possible sources for the infectious peritonitis in this presumably immuno-compromised patient. Antibiotic therapy covering the entire time period while the tube cystotomy was in place was considered; however, due to the lack of oral antibiotic options and the poor tolerance of long-term parenteral antibiotics, antimicrobial therapy was discontinued once the animal was discharged from hospital. Laparoscopic tube cystotomy has recently been described in male sheep (11), and may be a viable alternative in alpacas.

Phenylbutazone was used as an anti-inflammatory and analgesic drug; however, its use did not significantly change the clinical signs. The severe cystitis and pyelonephritis and the neoplasm likely contributed to the cachectic metabolic state of this animal on readmission to the hospital and undoubtedly contributed to the dysmaturity in the fetus. CVJ

Figure 1
Photomicrographs of a urogenital leiomyosarcoma in an alpaca with metastasis to a regional lymph node. A — Interlacing bundles and streams of elongated spindle-shaped cells. Hematoxylin and eosin (H & E). Bar = 50 μm. B — ...
Figure 2
Photomicrographs of a urogenital leiomyosarcoma in an alpaca following immunohistochemistry for vimentin (A), desmin (B), and smooth muscle actin (C). Cytoplasmic immunohistochemical labeling was uniformly strong for vimentin and desmin, and variably ...

Footnotes

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.

References

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