Ch 82 AGASACA Flashcards
Basal Cell Tumors
ddx MCT
- now categorized as specific adnexal tumors (e.g., trichoblastomas)
- rarely invade the underlying fascia.
- Lesions in cats may be multicentric
- feline may have relatively high mitotic rate
- dogs and cats clinically behave in a benign fashion, and metastasis and recurrence are considered rare (though reported in cats)
- surgical resection is the treatment of choice with good prognosis.
Perianal Hepatoid Gland Tumors
- modified sebaceous glands situated in the dermis surrounding the anus, tail base, prepuce, and some regions of the trunk in dogs.
- not found in cats
- diagnosis of adenoma versus adenocarcinoma can only be made histologically
adenoma
- benign, predominantly sex hormone–dependent tumors
- either stimulated by androgens or depressed by estrogens
- Intact male dogs are predisposed;
- Most of the male dogs are cured with surgical castration (tumor regresion)
- partial regression may occur in the remainder, enabling easier surgical resection
adenocarcinoma
- intact and castrated males and females > no clear hormone dependency.
- large masses with rapid growth (cf adenoma)
- metastasize in 15% of the cases at presentation (sublumbar) lymph nodes, lungs, liver, kidneys, and bone
- require adequate surgical margins. Up to 50% of the anal sphincter can be removed with only transient loss of continenc
What breeds are predisposed to hepatoid gland adenomas?
Cocker Spaniels
Beagles
Bulldogs
Samoyeds
Biological Behavior
- high potential for early metastasis
- either as a visible large subcutaneous mass in the perineal region or as a small nodule, incidentally found
- Several studies: association between the size and the presence of regional metastases
- recent study: 20% < 2cm already metastasized to the LNs
- size of the LNs does not indicate their metastatic status, as 90% of small-/normal-sized LNs could already be metastatic
- only one anal sac is affected, but bilateral involvement has been reported in 4–20%
- metastatic rate: 36% to 96%
- paraneoplastic hypercalcemia (tumor produced PTHr peptide) in 27% to 53%
- sublumbar lymph nodes (47% @ presentation)
- lungs (8%), liver, spleen, and bone may occur late in the disease
- negative prognostic role of hypercalcemia is still controversial
CS and Dx
- Median age 10 years
- A hormonal dependence not suggested
- no sex predisposition
- CS due to primary mass, paraneoplastic hypercalcemia, or pelvic obstruction from enlarged sublumbar lymph nodes
- 39% incidental
- dx by histology or cytology.
- Staging should include evaluation of the abdomen (ultrasonography or computed tomography [CT]) and thorax (radiography or CT) for metastasis.
- hyperclcaemia can cause renal failure
- complete excision is difficult because of the proximity of the rectum and anus
Tx
- Surgical excision of both the primary tumor and the SNLs is the mainstay of treatment;
- adjuvant chemotherapy has not been proven to be beneficial,
- targeted therapy, as well as RT, have shown promise in improving survival outcomes.
Prospective studies required
prognosis
- locally invasive tumor with a high potential for early metastasis
- longer survival for Sx with adjunctive
- highest MST (22–32 months) was reported with radiation therapy (RT)
- subset of tumors with more aggressive behavior and higher metastatic potential
- Local recurrence varies widely from 13 to 44% and is not associated with the completeness of surgical excision
- the number of metastatic LNs appears to have a better prognostic value than their size
- no imaging techniques sufficiently reliable in determining both size and metastatic status, and only histology can confirm the diagnosis.
- MST significantly shorter than that of dogs without distant metastases
- The excision of recurrent LNs metastasis improves the survival time
- STUDY: surgically resected AGASACA < 3.2 cm without metastases and treated with surgery alone was examined. For all 34 dogs, the median survival was 1237 days (3.4 years)
overall improvement in median survival time (MST)
chemo alone MST?
(15–28 months) 851 days
- treated with surgery and adjuvant therapy
- compared with chemotherapy alone (6.9 to 8.7 months).
negative prognostic factors (6)
cino 2024 review MDPI
- size of the primary tumor (contraversial)
- metastatic lymph nodes @ presentation,
- size and number of metastatic lymph nodes,
- distant metastases @ presentation,
- histological characteristics
- medical mgmt (rather than sx)
- hypercalcaemia debated
Postive: sx and l.n. removal
cytology
- suggests a neuroendocrine origin
- high cellularity
- clusters of round/polygonal cells with few characteristics of atypia, low cohesiveness and poorly defined margins.
- Anisokaryosis and anisocytosis may be mild
- cells with free round nuclei with reticular chromatin
prognostic significance of histological and immunohistochemical factors
three distinct histological patterns: solid, rosette, and tubular
- solid pattern was associated with a worse prognosis
- tumor necrosis,
- lymphovascular invasion,
- peripheral infiltration,
- cellular pleomorphism
How do anal sac tumours of cats compared with those of dogs?
Seem to more aggressive with a poorer prognosis. MST after surgery 3 months
Amsellem 2019 – AGASAC in 30 cats
perineal ulceration and discharge most common clinical sign
- local recurrence in 11/30 at median 96 days
- associated with incomplete margins and high nuclear pleomorphic score
- high nuclear pleomorphic score associated with shorter DFI and higher risk of death
- mDFI 234 days, MST 260 days
marginal excision not recommended in cats
Outcomes of dogs with apocrine gland anal sac adenocarcinoma treated via modified closed anal sacculectomy (2015-2022)
Davey 2024
pripich
modified closed anal sacculectomy for 47 AGAGSAC
- with complete excision of the duct
- compared to previously reported recurrence rates 18-50%
- 45/47 available for long-term evaluation
- local recurrence 1/45 (2.2%) at 90 days
- MST for 20/45 deceased dogs 388 days
- complications: overall 15/47 (31.9%), 3/15 major – 2/3 dehiscence
Jones 2023 – A relatively high proportion of dogs with small apocrine gland anal sac adenocarcinoma (AGASACA) primary tumours present with locoregional lymph node metastasis
VCO
metastatic rate: primary tumour <2cm = 20% initial, >2cm 63%
- 19% tumours <2cm → LN metastasis over median 179 days → overall 35% rate
- tumour size associated with metastasis
- hypercalcaemia not associated with presence of LN metastasis
Short- and long-term outcomes associated with anal sacculectomy in dogs with massive apocrine gland anal sac adenocarcinoma
Griffin 2023
oblak
outcomes for 28 dogs with AGASAC >5cm
- complications: 18% intraoperative, 36% post-operative
- no permanent fecal incontinence, tenesmus or anal stenosis
- local recurrence 37%, data on completeness of excision not available
- LN metastasis at the time of surgery more likely to develop new/progressive LN metastasis (59% vs 0%) and distant metastasis (41% vs 0%)
- median PFI 204 days, median overall survival 671 days
- nodal metastasis at time of sx correlated with shorter PFI, not survival
- adjuvant therapy not associated with outcome
Morello 2021 – prognostic factors for AGASAC
animals
ve px indicators: overall: metastasis to regional LN, necrosis, inflammatory infiltration
- dogs with metastatic disease: tumour size (>5.25cm), solid histologic pattern,
lymphatic/vascular infiltration
- LN metastasis → decreased DFI
- Ki67 index not associated with survival time or DFI
- hypercalcemia unclear
- surgery+toceranib → 57.14% progression, MST 877 days, median DFI 283 days
