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

Histopathological diagnosis and surgical complications following bilateral anal sacculectomy for the treatment of unilateral canine apocrine gland anal sac adenocarcinoma: 35 cases (2019-2023)

OBJECTIVES

To report the histopathological diagnosis of both anal sacs in dogs undergoing bilateral anal sacculectomy for the treatment of unilateral apocrine gland anal sac adenocarcinoma and to compare the surgical complication rate associated with this procedure in this population with previously published literature.

MATERIALS AND METHODS

Records were retrospectively reviewed for dogs that underwent bilateral anal sacculectomy for the treatment of apparently unilateral apocrine gland anal sac adenocarcinoma, at a single institute between 2019 and 2023. Clinical staging, surgical treatment, histological findings, intra- and postoperative complications were evaluated.

RESULTS

Thirty-five dogs were included. Only five of 35 (14%) dogs were found to have histologically normal contralateral anal sacs. Non-neoplastic anal sac disease was found in 23 of 35 (66%) dogs and bilateral apocrine gland anal sac adenocarcinoma was seen in seven of 35 (20%) dogs. None of the dogs diagnosed with bilateral neoplasia had evidence of bilateral neoplasia before surgery despite a thorough work-up. Complications attributable to the primary tumour removal were seen in 9% of dogs intraoperatively and 14% of dogs postoperatively, commonly tumour capsule disruption and surgical site infection, respectively.

CLINICAL SIGNIFICANCE

Bilateral anal sac disease was diagnosed histologically in the majority of presumed normal anal sacs, with 20% of cases being found to have bilateral apocrine gland anal sac adenocarcinoma. The surgical complication rates of this cohort were comparable to those reported for unilateral anal sacculectomy alone. These findings promote and encourage the use of bilateral anal sacculectomy in cases of suspected unilateral anal sac neoplasia.

Association between total hypercalcaemia and iliosacral lymph node metastasis in dogs diagnosed with anal sac adenocarcinoma using abdominal ultrasonography

BACKGROUND

Anal sac adenocarcinoma (ASACA) in dogs is a malignant perianal tumour that often metastasizes to the iliosacral lymph nodes. Additionally, this tumour can be associated with hypercalcemia of malignancy. To date, no study has looked at the association between increased blood calcium levels and suspected or confirmed lymph node metastasis as a primary objective.

OBJECTIVE

The objective of this study was to determine if increased total serum calcium level is associated with iliosacral lymph node metastasis in dogs diagnosed with ASACA.

METHODS

Medical records of a single referral hospital were searched to identify dogs examined between 2011 and 2021 that had a diagnosis of ASACA via cytology or histopathology. Only dogs that had serum total calcium recorded and abdominal ultrasound were included in the study. All images were reviewed by a board-certified radiologist blinded to any patient identifiers.

RESULTS

Of the 58 dogs, 33% (19/58) had total hypercalcaemia, and of these, 68% had confirmed or suspected iliosacral lymph node metastasis. Total hypercalcaemia was significantly associated with confirmed or suspected iliosacral lymph node metastasis (p < 0.01). However, 46% (11/24) of dogs with confirmed or suspected iliosacral lymph node metastasis were normocalcaemic.

CONCLUSIONS

Based on these results, it is suggested that while the presence of total hypercalcaemia may increase the likelihood of concurrent lymph node metastasis, total hypercalcaemia alone cannot be used as a screening tool for lymph node metastasis. Dogs diagnosed with ASACA should undergo full staging regardless of total serum calcium values.

A relatively high proportion of dogs with small apocrine gland anal sac adenocarcinoma (AGASACA) primary tumours present with locoregional lymph node metastasis

Apocrine gland anal sac adenocarcinoma (AGASACA) is a highly relevant disease in dogs, with a high rate of lymph node (LN) metastasis during the course of disease. A recent study showed that risk for death and disease progression was significantly associated with primary tumour size less than 2 and 1.3 cm, respectively. The objective of this study was to report the proportion of dogs that have primary tumours less than 2 cm in diameter, that are diagnosed with LN metastasis at presentation. This was a single site retrospective study of dogs that underwent treatment for AGASACA. Dogs were included if physical examination primary tumour measurements were available, abdominal staging was performed, and confirmation of abnormal lymph nodes by cytology or histology was done. Over a 5-year period, 116 dogs were included for review with 53 (46%) having metastatic LN at presentation. The metastatic rate for dogs with primary tumours <2 cm was 20% (9 of 46 dogs) compared to 63% (44 of 70 dogs) in dogs with primary tumours ≥2 cm. The association between tumour size group (<2 vs. ≥2 cm) and the presence of metastasis at presentation was significant (P < .0001) with an OR of 7.0 (95% CI: 2.9-15.7). Primary tumour size was significantly associated with LN metastasis at presentation but the proportion of dogs that presented with LN metastasis in the <2 cm group was relatively high. This data suggests that dogs with small tumours may still have aggressive tumour biology.

Complications associated with iliosacral lymphadenectomy in dogs with metastatic apocrine gland anal sac adenocarcinoma

OBJECTIVE

To report intraoperative and immediate postoperative complications associated with removal of metastatic iliosacral lymph nodes in dogs with apocrine gland anal sac adenocarcinoma.

ANIMALS

There were 136 client-owned dogs in the study.

PROCEDURE

Retrospective multi-institutional study. The database of collaborating institutions was searched for dogs with metastatic apocrine gland anal sac adenocarcinoma that underwent lymphadenectomy for removal of one or more iliosacral lymph nodes. Information of signalment, hematological abnormalities, abdominal computed tomography or ultrasound findings, number and size of enlarged lymph nodes, intraoperative and postoperative complications, treatment and outcome were collected.

RESULTS

The overall complication rate associated with metastatic iliosacral lymphadenectomy was 26.1%. The only intraoperative complication recorded was hemorrhage and was reported in 24 (17.6%) surgeries, 11 (45.8%) of which received a blood transfusion. Postoperative complications were reported in 10.4% of surgeries, and included edema formation (n = 4, 2.6%), unilateral or bilateral paraparesis (n = 4, 2.6%), hypotension (n = 3, 2.0%), surgical site infection (n = 2, 1.3%), abdominal incision dehiscence (n = 1, 0.6%), urinary incontinence (n = 1, 0.6%), and death (n = 1, 0.6%). The size of the iliosacral lymph nodes was significantly associated with a greater risk of complications, hemorrhage, and the need of transfusion during lymphadenectomy for metastatic apocrine gland anal sac adenocarcinoma.

CONCLUSION

Complications associated with iliosacral lymphadenectomy for metastatic apocrine gland anal sac adenocarcinoma are relatively common and mostly relate to hemorrhage. These complications are significantly associated with the size of the extirpated metastatic lymph nodes.

CLINICAL RELEVANCE

This retrospective study provides information for the clinician regarding the potential surgical complications for extirpation of metastatic iliosacral lymph nodes. These complications, although not common, can be severe and should be discussed with owners before surgery.

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.

Canine anal sac gland carcinoma with regional lymph node metastases treated with sacculectomy and lymphadenectomy: Outcome and possible prognostic factors

The staging system commonly used in canine anal sac gland carcinoma (ASGC) is a revised Tumour-Node-Metastasis (TNM) system published in 2007. This staging system consists in four stages and, for dogs with nodal metastases, the size of the metastatic lymph node (mLN) defines the N stage. However, we hypothesise that (1) the mLN size has no prognostic significance when the mLN can be excised, (2) a high number of mLNs is associated with poorer prognosis and (3) the measurement of the mLN on imaging is not reproducible. To investigate these hypotheses, medical records and diagnostic images of dogs with ASGC and mLN, treated with sacculectomy and lymphadenectomy, with or without chemotherapy, were reviewed. Interobserver variability for mLN measurement was assessed. Prognostic factors including mLN size and number were investigated. Time to documented progression (TDP) and disease-specific survival (DSS) were evaluated. Progression-free interval (PFI) was analysed with interval-censored data analysis. Fifty-seven dogs were included. The median PFI, TDP and DSS were 110 (95%CI 61.5-185.5), 196 (95%CI 162-283) and 340 days (95%CI 321-471), respectively. For measurement of the largest mLN, interobserver agreement was excellent but limits of agreement reached 39.7%. Neither the size of the largest mLN nor the use of adjuvant chemotherapy were associated with outcome. The number of mLNs was associated with outcome and having more than four mLNs was associated with shorter PFI (p < .001), TDP (p = .004) and DSS (p < .001). While mLN size measurement was not consistently reproducible and did not influence outcome in our cohort, number of mLNs did. Further studies are required for development of a revised staging system.

Anal sacculiths may be an incidental finding in dogs

Mineral-attenuating material is occasionally seen in the anal sacs of dogs during abdominal CT studies. This retrospective, descriptive study was performed to estimate the prevalence and CT appearance of this mineral-attenuating material. A total of 357 abdominal CTs were reviewed retrospectively. The mineral-attenuating material was most easily identifiable using the brain window setting (window width: 120 HU; window level: 40 HU). In the current study, the prevalence of mineral-attenuating material in the anal sacs was 7.6% (95% confidence interval, 5.0-10.8%) with 48.1% bilateral involvement and equal distribution in the right and left in dogs with unilateral involvement. Successful collection and material analysis were performed in three dogs. The material was determined to be 100% dried blood, 100% waxy matter, and a "small amount of fat enmeshed in unidentified noncrystallined material." Given the CT appearance and the Hounsfield unit of these mineral-attenuating material within the anal sacs, the term "anal sacculiths" is proposed. All dogs with anal sacculiths within this study population did not have any reported disease of the anal sacs.

A combined protocol with piroxicam, chemotherapy, and whole pelvic irradiation with simultaneous boost volumetric modulated arc radiotherapy for muscle-invasive canine urinary transitional cell carcinoma: First clinical experience

The aims of this pilot study were to evaluate the feasibility and efficacy of high-dose hypofractionated volumetric modulated arc radiotherapy (VMAT) applied to whole pelvic region radiotherapy (WPRT) with multilevel simultaneous integrated boost (MLSIB) combined with piroxicam and chemotherapy for the treatment of canine transitional cell carcinoma (TCC) of the lower urinary tract with muscle invasion TCC. Twelve dogs were enrolled, according to stage, in two groups: group 1, TCC confined to the urinary tract; group 2, TCC with metastasis. The planning target volume dose was tailored from 36 to 42 Gy in 6 fractions. All dogs were prescribed piroxicam and radiosensitizing carboplatin, and six received chemotherapy after radiotherapy. Serial follow-ups with computed tomography and magnetic resonance imaging were performed. Disease control and toxicity effects were evaluated according to the Response Evaluation Criteria in Solid Tumors and Veterinary Radiation Therapy Oncology Group criteria. The treatment was well tolerated, and no high-grade side effects were reported. The median overall survival times for groups 1 and 2 were 1,230 and 150 days, respectively. A considerable percentage of patients in group1 (50%) were still alive at the time of writing this paper, and a longer follow-up could enable a more accurate survival analysis. This preliminary analysis shows that VMAT applied to the WPRT with MLSIB is an effective and safe option for dogs with lower urinary TCC, although the presence of metastases worsens the prognosis.

Evaluation of radiographs for the detection of sublumbar lymphadenopathy in dogs

The purpose of this study was to evaluate radiographs for the detection of sublumbar lymph node (SLN) enlargement. Ultrasound was used to determine SLN size. Twenty-two dogs with anal gland adenocarcinoma or lymphoma were prospectively included, with 16/22 having SLN enlargement on ultrasound. Twenty-one dogs without enlargement were retrospectively included as controls. Three blinded observers evaluated 43 right lateral abdominal radiographs for the presence of SLN enlargement. Sensitivity and specificity of radiographs for the detection of SLN enlargement were 81%/70%, 94%/81%, and 75%/100% for a general practitioner, imaging resident, and radiologist, respectively. Ventral displacement of the colon, a soft tissue opacity in the caudal retroperitoneal space and loss of conspicuity of the ventral margin of the iliopsoas muscle were radiographic findings significantly associated with identification (P-values < 0.05). Markedly enlarged SLNs (> 21.5 mm) were consistently detected radiographically by observers with specialist imaging training. Key clinical message: Radiographic visualization should raise suspicion of neoplastic infiltration of SLN but lack of visualization does not exclude mild to moderate enlargement. Additional imaging such as ultrasound or computed tomography remains important to confirm or exclude sublumbar lymphadenopathy.

Comparison of methods to determine primary tumour size in canine apocrine gland anal sac adenocarcinoma

OBJECTIVES

To assess agreement between measurement of primary apocrine gland anal sac adenocarcinoma tumours using digital palpation, CT and formalin-fixed tissue and to look for associations with metastasis at presentation.

MATERIALS AND METHODS

Retrospective study of different methods of measuring primary tumour size in histopathologically-confirmed canine apocrine gland anal sac adenocarcinoma.

RESULTS

One hundred sixteen tumours from 107 dogs were included. There was moderate agreement between maximal dimension of the primary tumour measured by CT compared to formalin-fixed tissue and digital palpation. There was no significant difference in median maximum dimension between the measurement methods. Vascular invasion, CT stage, digital rectal examination stage and formalin-fixed tissue stage were significantly associated with metastasis at presentation, while mitotic index of the primary tumour was not. Dogs with tumours >2.5 cm (tumour-stage 2) were significantly more likely to present with metastatic disease.

CLINICAL SIGNIFICANCE

In canine apocrine gland anal sac adenocarcinoma, primary tumour size, tumour-stage and vascular invasion are strong predictors of metastasis at presentation.

Survival analysis in dogs with urinary transitional cell carcinoma that underwent whole-body computed tomography at diagnosis

This retrospective study aimed to evaluate factors associated with survival and to compare characteristics between tumour localizations in dogs with urinary transitional cell carcinoma (TCC) that underwent whole-body computed tomography (CT) at diagnosis. Dogs with histologically confirmed TCC that received medical therapy between 2010 and 2017 were included; dogs that underwent surgery or radiotherapy for the primary tumour were excluded. According to the CT findings, primary tumour localization (classified into the Bladder, Urethra and Bladder and Urethra groups), prostate involvement, iliosacral lymphadenomegaly, sternal lymphadenomegaly and metastasis to the bone and lung were evaluated for survival analysis. CT at diagnosis revealed iliosacral lymphadenomegaly, sternal lymphadenomegaly, bone metastasis and lung metastasis in 47.7%, 18.5%, 24.6% and 35.4% of the 65 included dogs, respectively. The overall median survival time was 196 days. On multivariable analysis, TCC localization (hazard ratio [HR], 1.90; P = .037), bone metastasis (HR, 2.76; P = .013) and sternal lymphadenomegaly (HR, 3.56; P = .004) were significantly associated with survival. Compared to the Bladder group (n = 16), the Urethra group (n = 26) had higher metastasis rates to the bone (6.3% vs 42.3%; P = .045) and lung (6.3% vs 46.2%; P = .022). The survival time was shorter in the Urethra group than in the Bladder group (121.5 vs 420 days; P < .001), and it was similar only in female dogs (247 vs 420 days; P = .031). These findings suggest that whole-body CT could be valuable for predicting the prognosis in urinary TCC.

Detection of human epidermal growth factor receptor 2 overexpression in canine anal sac gland carcinoma

Canine anal sac gland carcinoma (ASGC) frequently occurs in the apocrine glands of the canine anal sac and shows aggressive biological behavior. The expression of human epidermal growth factor receptor 2 (HER2) has been reported in various human and canine tumors. HER2 is a promising therapeutic target of these tumors, and HER2-targeted drugs, such as trastuzumab and lapatinib, have improved the outcome of these patients. In this study, HER2 expression in ASGC was evaluated to investigate its potential as a therapeutic target for canine ASGC. HER2 mRNA expression in surgically resected ASGC tissues was significantly higher than that in normal anal sac tissue. To evaluate the expression of HER2 protein, paraffin-embedded ASGC tissues were immunohistochemically evaluated. Strong and broad staining of HER2 was detected in ASGC tissues, while HER2 was weakly to moderately stained in normal anal sac apocrine glands and squamous epithelia. The degree of HER2 expression in ASGC tissues was scored based on its intensity and positivity (score: 0-3+). Scoring of HER2 expression revealed 6 samples (24%) scored 3+, 14 (56%) scored 2+, and 5 (20%) scored 1+, with no samples scoring 0. In all, 80% of canine ASGC tissues were positive for HER2 (scored ≥2+). Furthermore, putative HER2-overexpressed cells in ASGC were detected with trastuzumab by flow cytometry. These preliminary data may lead to further evaluation of the role of HER2 in canine ASGC as a mechanism of malignancy and as a therapeutic target for HER2-targeted therapy.

Nonselective Lymph Node Dissection and Sentinel Lymph Node Mapping and Biopsy

Clinical staging is important for determining the extent of disease in animals with malignant cancers. The status of the lymph node will help determine whether adjuvant treatment is indicated. Historically, the regional anatomic lymph node has been sampled to determine the presence or absence of metastatic disease, but there is increasing evidence that the regional anatomic lymph node is often different to the sentinel lymph node. As a result, several sentinel lymph node mapping techniques have been described for more accurate clinical staging of oncologic patients.

Imaging in Non-neurologic Oncologic Treatment Planning of the Head and Neck

Imaging is critical for the diagnosis and staging of veterinary oncology patients. Although cytology or biopsy is generally required for diagnosis, imaging characteristics inform the likelihood of a cancer diagnosis, can result in a prioritized list of differentials that guide further staging tests, and assist in the planning of surgery, radiation, and chemotherapy options. Advanced imaging, such as CT and MRI, can better define the extent of disease for surgical and radiation planning for head and neck cancer cases in particular. Additionally, new imaging technologies are continually being translated into veterinary fields, and they may provide more options for cancer patients as they become more widely available.

Bilateral medial iliac lymph node excision by a ventral laparoscopic approach: technique description

The aim of this study was to describe a ventral laparoscopic technique for bilateral medial iliac lymphadenectomy in dogs. Twelve intact male purpose-bred research dogs, weighing less than 15 kg, were positioned in dorsal recumbency, and a 3-portal technique was used. Bilateral dissection was performed with vessel-sealing devices while tilting the surgical table by up to 30° towards the contralateral side of the target medial iliac lymph node (MILN) without changing the surgeon’s position. Using a ventral laparoscopic approach, bilateral MILNs were identified and excised in all dogs. The mean times for unilateral and bilateral MILN dissections were 9.7 ± 3.8 and 21.0 ± 6.0 min, respectively. The mean times for the right and left MILN dissections were 10.8 ± 4.3 and 9.8 ± 2.5 min, respectively. The mean total surgery time was 43.7 ± 7.7 min. In total, 26 MILNs were dissected. Several complications, including mild to moderate capillary hemorrhage from perinodal fat and vessels (controlled laparoscopically), mild spleen trauma caused by the first trocar insertion and capsular damage of MILNs, were observed. However, there were no other major complications. All MILN samples were evaluated and deemed suitable for histopathologic diagnosis. Laparoscopic excision of MILNs is a useful method of excisional biopsy for histopathologic diagnosis. Using this ventral laparoscopic approach with the 3-portal technique, bilateral MILN dissection suitable for obtaining histopathologic samples could be achieved in a short time in dogs weighing less than 15 kg.