Surgical management of urethral obstruction secondary to perineal liposarcoma in a dog: a case report

BACKGROUND

Swelling of the perineal region in male dogs is most commonly caused by a perineal hernia. Clinical signs associated with perineal hernia are constipation, tenesmus or stranguria. This case report documents a rare cause of perineal swelling created by the growth of a malignant tumour leading to urethral obstruction and subsequent stranguria.

CASE PRESENTATION

An 11-year-old neutered male German Shepherd was presented for swelling in the perineal region and stranguria for three days. Complete blood count and serum biochemistry were unremarkable. Ultrasound revealed a heterogeneous mass in the perineal region. Retrograde urethrography showed a severe narrowing of the urethra caudal to the pelvis. A fine-needle aspirate of the mass was highly suspicious for liposarcoma. Staging was performed by computed tomography (CT) of the thorax and abdomen. Total penile amputation in combination with pubic-ischial pelvic osteotomy, transposition of the remaining urethra through the inguinal canal, V-Y-plasty cranial to the prepuce and preputial urethrostomy were performed to remove the tumour. Histopathology confirmed a well-differentiated liposarcoma with complete histological margins. Six months after the surgery the dog was doing well and there were no signs indicating local tumour recurrence.

CONCLUSIONS

Wide surgical excision is generally recommended for soft tissue sarcomas, however this is sometimes not feasible for large tumours. In the case reported here, tumour resection was achieved by a combination of several surgical techniques with a good clinical outcome.

Spotlight on capecitabine for the treatment of unresectable or metastatic carcinoma of various origin: A retrospective study of 25 dogs

Capecitabine, the oral prodrug of 5-fluorouracil, is indicated in people to treat various malignant epithelial cancers. In dogs, capecitabine has not been extensively evaluated. The aim of this retrospective study was to investigate toxicity and preliminary efficacy of single agent capecitabine in dogs with advanced malignant epithelial cancers of any site, for which no effective therapy existed, conventional treatment failed or was declined. Capecitabine was administered orally at 750 mg/m2 from day 1 to 14, followed by 1-week rest period, given as 3-week cycles. Safety evaluation was performed after 2 cycles, and every 2-3 cycles thereafter. Tumour response was determined every 2-3 cycles. Twenty-five dogs with hepatocellular carcinoma (n = 6), lung papillary carcinoma (n = 4), anal sac adenocarcinoma (n = 3), colic adenocarcinoma (n = 2), and other individually represented epithelial cancers (n = 10) were included. Dogs received a median of 4 cycles (range, 2-43) for a median of 84 days (range, 42-913). Toxicity occurred in 17 (68.0%) dogs; the most frequent adverse events were gastrointestinal, with the majority being self-resolving and of mild grade. Of the 22 dogs with macroscopic disease, 3 (13.6%) achieved partial remission, 16 (72.7%) were stable and 3 (13.6%) progressed; overall clinical benefit rate was 86.4%. Median progression-free interval was 93 days (95% CI 42-154; range, 1-521) and median tumour-specific survival was 273 days (95% CI 116-482; range 45-913). These findings suggest that capecitabine is an attractive option for the treatment of several types of carcinomas in dogs. Prospective studies are warranted to optimize the scheduling of capecitabine and confirm its efficacy.

Computed tomographic features of an axillary liposarcoma with hepatic metastasis

A geriatric dog presented for lethargy, dyspnea, and urinary incontinence. Thoracic radiographs demonstrated a large, mixed fat, and soft tissue opaque axillary mass and a pulmonary mass. Computed tomography (CT) further characterized these masses and revealed innumerable fat-attenuating hepatic masses and cranial mediastinal lymphadenopathy. Histopathology of the axillary and hepatic masses confirmed grade two primary axillary liposarcoma with hepatic metastasis. Cytology of the pulmonary mass was consistent with a pulmonary carcinoma. This is the first published CT description of fat-attenuating metastatic hepatic liposarcoma in a dog.

Histopathological Features of Myxoid Pleomorphic Liposarcoma in an African Pygmy Hedgehog (Atelerix Albiventris)

Myxoid pleomorphic liposarcoma is characterized by pathological features of both pleomorphic liposarcoma and myxoid liposarcoma, as the name suggests. In this case, a myxoid pleomorphic liposarcoma was observed in a 5-year-old male African pygmy hedgehog. It consisted of ~60% of the myxoid substance area with proliferating round cells and ~30% of pleomorphic neoplastic cells. The subject presented with extrapulmonary metastasis, but a good prognosis during 6 months of follow-up, which is similar to the characteristics of myxoid liposarcoma. The histopathological features of myxoid pleomorphic liposarcoma may reflect the features of either myxoid liposarcoma or pleomorphic liposarcoma depending on the proportion of each histopathological feature. The proportion of the pleomorphic area and the myxoid area may offer information on the prognosis and metastasis of myxoid pleomorphic liposarcoma, which will be helpful for setting up a treatment plan. Thus, analyzing the proportion of pleomorphic area and myxoid area could be suggested as one of the ways to predict clinical outcomes. In addition to the fact that this is the first case of a myxoid pleomorphic liposarcoma in hedgehogs, this case is meaningful, considering the unique histopathological characteristics and rare incidence of myxoid pleomorphic liposarcoma that could be important in humans as well.

Liposarcoma of the spermatic cord in a Toy Poodle

Liposarcoma of the spermatic cord is extremely rare in dogs and humans. This report describes the clinical signs, typical diagnostic imaging including ultrasound and computed tomography, and treatment of a liposarcoma of the spermatic cord of a Toy Poodle confirmed by histological examination after a surgical procedure. This case highlights the importance of preoperative diagnostic imaging and histopathological examination in dogs with an inguinal or scrotal mass.

Metastatic Liposarcoma in a South African Fur Seal (Arctocephalus pusillus)

A 14-year-old female South African fur seal (Arctocephalus pusillus) was presented with a large skin mass on the right shoulder. At necropsy examination, multiple white nodules were found in the lungs, liver, spleen and right axillary lymph nodes. Histologically, the skin mass was composed of round to polygonal neoplastic cells with round to oval nuclei and variably sized cytoplasmic vacuoles. Cellular and nuclear atypia were prominent. Immunohistochemically, the neoplastic cells expressed vimentin, but not cytokeratins, S100 protein, adipophilin or desmin. The cytoplasmic lipid droplets stained positively with oil red O. Metastasis was seen in the lungs, liver, spleen and right axillary lymph nodes, with similar morphological features to the skin mass. Based on these findings, a diagnosis of a pleomorphic liposarcoma with systemic metastasis was made. No previous reports of metastatic liposarcomas have been published in marine mammals.

Liposarcoma in animals: literature review and case report in a domestic pig (Sus scrofa)

Liposarcomas are malignant tumors of adipocytes. The current report describes a liposarcoma in a 2.5-year-old, mixed-breed commercial sow that was detected during meat inspection. On gross examination, a firm, whitish, multinodular, 20 cm ×10 cm mass was observed in the perirenal area along with smaller nodules multifocally scattered within the renal parenchyma. Histological examination revealed an anaplastic sarcoma with clear intracytoplasmic lipidic vacuoles that were positive for Sudan black staining. Most of the cells were also positive for S100 and vimentin immunohistochemistry. Based on these results, a diagnosis of a perirenal liposarcoma was established. To the authors' knowledge, no previous reports of liposarcomas in pigs have been published. This report also includes a review of the literature published on animal liposarcomas.

Assessment of plasma uracil-to-dihydrouracil concentration ratio as an indicator of dihydropyrimidine dehydrogenase activity in clinically normal dogs and dogs with neoplasia or renal insufficiency

OBJECTIVE

To determine and compare the ratio of uracil (U) to dihydrouracil (UH(2)) concentrations in plasma as an indicator of dihydropyrimidine dehydrogenase activity in clinically normal dogs and dogs with neoplasia or renal insufficiency.

ANIMALS

101 client- and shelter-owned dogs.

PROCEDURES

Study dogs included 74 clinically normal dogs, 17 dogs with neoplasia, and 10 dogs with renal insufficiency. For each dog, a blood sample was collected into an EDTA-containing tube; plasma U and UH(2) concentrations were determined via UV high-performance liquid chromatography, and the U:UH(2) concentration ratio was calculated. Data were compared among dogs grouped on the basis of sex, clinical group assignment, reproductive status (sexually intact, spayed, or castrated), and age.

RESULTS

Mean ± SEM U:UH(2) concentration ratio for all dogs was 1.55 ± 0.08 (median, 1.38; range, 0.4 to 7.14). In 14 (13.9%) dogs, the U:UH(2) concentration ratio was considered abnormal (ie, > 2). Overall, mean ratio for sexually intact dogs was significantly higher than that for neutered dogs; a similar difference was apparent among males but not females. Dogs with ratios > 2 and dogs with ratios ≤ 2 did not differ significantly with regard to sex, clinical group, reproductive status, or age.

CONCLUSIONS AND CLINICAL RELEVANCE

Determination of the U:UH(2) concentration ratio was easy to perform. Ratios were variable among dogs, possibly suggesting differences in dihydropyrimidine dehydrogenase activity. However, studies correlating U:UH(2) concentration ratio and fluoropyrimidine antimetabolite drug tolerability are required to further evaluate the test's validity and its appropriate use in dogs.