Computed tomographic staging of dogs with anal sac adenocarcinoma.

OBJECTIVES: To describe the CT appearance of anal sac adenocarcinoma lesions in a population of dogs including the relations between primary tumour, and locoregional and distant metastasis. MATERIALS AND METHODS: Retrospective review of dogs with confirmed anal sac adenocarcinoma and available CT images of the thorax, abdomen and pelvis. RESULTS: A population of 70 dogs were included in the study. No association was found between anal sac mass size and presence or absence of iliosacral lymph node enlargement. The prevalence of local metastatic disease characterised by iliosacral lymphadenomegaly in this study was 71%, with pulmonary metastases identified in 11% of cases. There were no cases of distant pulmonary metastasis without concurrent locoregional lymphadenomegaly. CLINICAL SIGNIFICANCE: In our population of dogs local metastatic spread of anal sac adenocarcinoma was common, with a relatively low prevalence of pulmonary metastasis. The study demonstrates the importance of thorough rectal examination and/or imaging to assess the iliosacral lymph centre in this disease irrespective of the size of the anal sac mass.

Malignant perineal tumors in dogs: the contribution of computed tomography for staging and surgical planning / Tumores perineais malignos em cães: contribuição da tomografia computadorizada para estadiamento e planejamento cirúrgico

The contribution of computed tomography for staging and surgical planning of malignant perineal tumors in dogs is discussed. Five dogs diagnosed with malignant perineal neoplasms underwent to computed tomography (CT) examination. The CT image enabled investigation of cleavage planes between neoplastic lesions and adjacent structures such as the rectum, anus, vagina, urethra and perineal muscles. Accurate assessment regional lymph nodes and adjacent bone structures was also possible. All tumors evaluated in this region presented heterogeneous appearance in pre and postcontrast CT images, but only the anal sac adenocarcinomas presented lymphadenopathy. Computed tomography proved to be a valuable tool for tumor staging and determination of lesion extension and invasion of adjacent tissues, providing significant contributions to clinical and surgical therapeutic planning.(AU)

A contribuição da tomografia computadorizada para estadiamento e planejamento cirúrgico de tumores perineais malignos em cães é discutida. Cinco cães diagnosticados com neoplasias perineais malignas foram submetidos ao exame de tomografia computadorizada (CT). A imagem por TC permitiu a investigação de planos de clivagem entre as lesões neoplásicas e estruturas adjacentes, como o reto, o ânus, a vagina, a uretra e os músculos perineais. A avaliação precisa dos linfonodos regionais e estruturas ósseas adjacentes também foi possível. Todos os tumores avaliados nesta região apresentaram aspecto heterogêneo nas imagens de TC pré e pós-contraste, mas apenas os adenocarcinomas de saco anal apresentaram linfonodopatia. A tomografia computadorizada mostrou ser uma ferramenta valiosa para o estadiamento da neoplasia, determinação da extensão da lesão e invasão de tecidos adjacentes, proporcionando contribuições significativas para o planejamento terapêutico clínico e cirúrgico.(AU)

INDIRECT COMPUTED TOMOGRAPHIC LYMPHOGRAPHY FOR ILIOSACRAL LYMPHATIC MAPPING IN A COHORT OF DOGS WITH ANAL SAC GLAND ADENOCARCINOMA: TECHNIQUE DESCRIPTION.

Sentinel lymph node mapping can help to direct surgical oncologic staging and metastatic disease detection in patients with complex lymphatic pathways. We hypothesized that indirect computed tomographic lymphography (ICTL) with a water-soluble iodinated contrast agent would successfully map lymphatic pathways of the iliosacral lymphatic center in dogs with anal sac gland carcinoma, providing a potential preoperative method for iliosacral sentinel lymph node identification in dogs. Thirteen adult dogs diagnosed with anal sac gland carcinoma were enrolled in this prospective, pilot study, and ICTL was performed via peritumoral contrast injection with serial caudal abdominal computed tomography scans for iliosacral sentinel lymph node identification. Technical and descriptive details for ICTL were recorded, including patient positioning, total contrast injection volume, timing of contrast visualization, and sentinel lymph nodes and lymphatic pathways identified. Indirect CT lymphography identified lymphatic pathways and sentinel lymph nodes in 12/13 cases (92%). Identified sentinel lymph nodes were ipsilateral to the anal sac gland carcinoma in 8/12 and contralateral to the anal sac gland carcinoma in 4/12 cases. Sacral, internal iliac, and medial iliac lymph nodes were identified as sentinel lymph nodes, and patterns were widely variable. Patient positioning and timing of imaging may impact successful sentinel lymph node identification. Positioning in supported sternal recumbency is recommended. Results indicate that ICTL may be a feasible technique for sentinel lymph node identification in dogs with anal sac gland carcinoma and offer preliminary data to drive further investigation of iliosacral lymphatic metastatic patterns using ICTL and sentinel lymph node biopsy.

Ultrasound and computed tomography of the iliosacral lymphatic centre in dogs with anal sac gland carcinoma.

In this prospective study, we hypothesized that computed tomography (CT) would identify more normal and abnormal iliosacral lymph nodes (LNs) than abdominal ultrasound in dogs with anal sac gland carcinoma (ASGC). Twelve client-owned dogs with ASGC but without distant metastasis were enrolled. Abdominal ultrasound and contrast-enhanced CT scans of the abdomen were obtained. Iliosacral LNs were counted and assessed for location, laterality and size. Significantly (P < 0.00001) more iliosacral LNs were identified with CT (61) than ultrasound (30), including significantly (P = 0.00012) more medial iliac LNs with CT (33) than ultrasound (19). There was no difference in number of internal iliac LNs identified with CT versus ultrasound. Significantly (P = 0.000061) more sacral LNs were identified with CT (15) than ultrasound (0). Ultrasound identified slightly more (7) abnormal iliosacral LNs than CT (5). Contrast CT was able to identify more normal but not more abnormal LNs than ultrasound.

Utility of Computed Tomography versus Abdominal Ultrasound Examination to Identify Iliosacral Lymphadenomegaly in Dogs with Apocrine Gland Adenocarcinoma of the Anal Sac.

BACKGROUND: Apocrine gland adenocarcinoma of the anal sac (AGAAS) is associated with high rates of iliosacral lymph node metastasis, which may influence treatment and prognosis. Magnetic resonance imaging (MRI) recently has been shown to be more sensitive than abdominal ultrasound examination (AUS) in affected patients. OBJECTIVE: To compare the rate of detection of iliosacral lymphadenomegaly between AUS and computed tomography (CT) in dogs with AGAAS. ANIMALS: Cohort A: A total of 30 presumed normal dogs. Cohort B: A total of 20 dogs with AGAAS that underwent AUS and CT. METHODS: Using cohort A, mean normalized lymph node : aorta (LN : AO) ratios were established for medial iliac, internal iliac, and sacral lymph nodes. The CT images in cohort B then were reviewed retrospectively and considered enlarged if their LN : AO ratio measured 2 standard deviations above the mean normalized ratio for that particular node in cohort A. Classification and visibility of lymph nodes identified on AUS were compared to corresponding measurements obtained on CT. RESULTS: Computed tomography identified lymphadenomegaly in 13 of 20 AGAAS dogs. Of these 13 dogs, AUS correctly identified and detected all enlarged nodes in only 30.8%, and either misidentified or failed to detect additional enlarged nodes in the remaining dogs. Despite limitations in identifying enlargement in all affected lymph nodes, AUS identified at least 1 enlarged node in 100% of affected dogs. CONCLUSION AND CLINICAL IMPORTANCE: Abdominal ultrasound examination is an effective screening test for lymphadenomegaly in dogs with AGAAS, but CT should be considered in any patient in which an additional metastatic site would impact therapeutic planning.

Comparison of abdominal ultrasound and magnetic resonance imaging for detection of abdominal lymphadenopathy in dogs with metastatic apocrine gland adenocarcinoma of the anal sac.

Imaging studies in humans with anal and rectal cancer indicate that magnetic resonance imaging (MRI) is a more sensitive technique than abdominal ultrasound (AUS) for the detection of abdominal lymphadenopathy. The purpose of this retrospective study was to directly compare the efficacy of these two techniques in detecting abdominal lymphadenopathy in dogs with apocrine gland adenocarcinoma of the anal sac (AGAAS). Six dogs with histologically confirmed AGAAS and histopathologic confirmation of metastasis to abdominal lymph nodes (LNs) had AUS and abdominal MRI. AUS identified lymphadenopathy in two of six dogs, whereas MRI identified lymphadenopathy in all the six dogs. Lymphadenopathy was predominantly sacral in location, with involvement of the medial iliac and hypogastric LNs in only two cases. These data suggest that MRI is more sensitive than AUS for detecting sacral abdominal lymphadenopathy in dogs with AGAAS. As such, MRI could be considered in any patient with AGAAS for initial staging of this disease.

Evaluation of an anal sac adenocarcinoma tumor in a Spitz dog.

A 9-year-old emasculated male Spitz with tenesmus and constipation had a subcutaneous mass at the left ventral aspect of the anus with history of polyuria and polydipsia. A complete blood cell count, serum biochemistry panel, and urinalysis (cystocentesis sample) were evaluated. Abnormalities in the serum biochemistry panel included a mildly elevated serum cholesterol concentration (7.28 mmol/L; reference interval, 2.70-5.94 mmol/L), increased serum alkaline phosphatase activity (184 U/L; reference interval, 9-90 U/L), alanine transaminase (122 U/L; reference interval, 5-60 U/L) activity and aspartate aminotransferase (80 U/L; reference interval, 5-55 U/L) activity, severe increased total calcium concentration (16.3 mg/dL; reference interval, 8.2-12.4 mg/dL or 9.3-11.4 mg/dL), and decreased total calcium concentration (3.4 mg/dL, reference interval, 2.5-5.6mg/dL). Furthermore, testing revealed an increased intact parathyroid hormone concentration (38.6 pmol/L; reference interval, 3-17 pmol/L). On cytologic and histopathologic examinations, various types of cells were observed. Most of the cells were oval to polygonal and had elliptical or elongate nuclei and a moderate amount of pale to basophilic cytoplasm. The remaining cells had round to oval nuclei and pale to basophilic cytoplasm. Cells of both types were loosely adhered to each other and were arranged in rosette-like structures. Both neoplastic cell types had fine homogenous chromatin and either a small indistinct nucleolus or no visible nucleolus. Mild anisokaryosis and anisocytosis were observed. Histologically, the mass consists of glandular structures formed by cuboidal cells admixed with bundles of spindle cells. Based on location and histologic features, the final diagnosis was adenocarcinoma of the apocrine gland of the anal sac, which should be included as a cytologic differential diagnosis when spindle cells and typical epithelial cells are observed in masses in the region of the anal sac of dogs.

Squamous cell carcinoma of the anal sac in a spotted hyena (Crocuta crocuta).

A 25-yr-old spayed female spotted hyena (Crocuta crocuta) developed intermittent right pelvic limb lameness that persisted following conservative medical therapy. No obvious musculoskeletal lesions were noted on initial physical exam; however, spinal radiography was suspicious for possible intervertebral degenerative joint disease or discospondylitis. Despite prolonged medical therapy, the lameness progressed to minimal weight bearing and marked muscle atrophy of the right pelvic limb. Electromyography showed spontaneous activity in the muscles of right sciatic nerve distribution. Sensory and motor nerve conduction velocities in the right tibial and peroneal nerves were undetectable and markedly reduced, respectively. A magnetic resonance imaging (MRI) scan revealed a large, space-occupying mass on the right side of the sacrum and pelvis. Antemortem fine-needle aspiration of the mass and postmortem histopathology resulted in diagnosis of a high-grade squamous cell carcinoma of the anal sac. Squamous cell carcinoma of the anal sac is very rare in domestic dogs and previously unreported in spotted hyenas.

Anal sac tumours of the dog and their response to cytoreductive surgery and chemotherapy.

A retrospective study of anal sac tumours without pulmonary metastases, from the author's clinical records for the period July 1989 to July 2002, was conducted to establish the response to treatment with surgery and melphalan chemotherapy. Of 21 dogs with tumours of the anal sacs 19 had apocrine gland adenocarcinomas of anal sac origin, one had a benign papillary cystadenoma and another had a malignant melanoma. Two of the 19 dogs had bilateral anal sac adenocarcinomas. Ten of the 19 dogs with apocrine gland adenocarcinomas of anal sac origin had sublumbar lymphadenopathy. Five dogs were excluded by their owners from recommended treatment. Fourteen dogs with apocrine gland adenocarcinomas of anal sac origin were treated by surgical cytoreduction and chemotherapy with melphalan. Seven of the 14 dogs had regional lymph node metastases. Cytoreduction was by local excision of the anal sac in all 14 dogs and concurrent removal of the sublumbar retroperitoneal lymph nodes in the seven dogs with regional lymph node metastases. The median survival time of dogs with sublumbar nodal metastasis was 20 months and for dogs with tumour localised to the anal sac the median survival time was 29.3 months. There was no difference in median survival of those dogs with sublumbar metastases compared to those without. This study suggests there is a role for melphalan in the treatment of dogs with anal sac adenocarcinoma when combined with cytoreductive surgery, with treatment survival times and the local recurrence rate of the primary tumour comparing favourably with previously published treatment regimes.

Ultrasonography of the medial iliac lymph nodes in the dog.

Sixty-one medial iliac lymph nodes of 38 different dogs (eight with adenocarcinoma of the apocrine glands of the anal sac, 13 with multicentric lymphoma, six with multicentric lymphoma but in clinical remission, and 11 control dogs) were evaluated to assess the ability of ultrasound to identify and interrogate these lymph nodes across the different groups and to differentiate these groups using different sonographic parameters. Ultrasound proved to be useful to assess canine medial iliac lymph nodes. An increase in size or number of detected lymph nodes or finding rounder or heterogeneous lymph nodes could differentiate lymph nodes of dogs of the control group from lymph nodes of dogs with lymphoma or an adenocarcinoma of the apocrine glands of the anal sac. Subcategories of malignancy could not be differentiated. More studies need to be performed, both with patients with reactive lymph nodes and also focusing on other canine superficial lymph nodes, before generalizing the results of this study to other areas or diseases.