Apocrine gland anal sac ADC accounts for 2% of all skin tumors. Anal sac ADC is more common in dogs and very rare in catsOther anal sac tumors include adenoma and SCC. Metastasis and hypercalcemia is rare in cats with anal sac ADC but common in dogs.Metas: 56%-79% metastatic rate at the time of diagnosis with regional lymph node very common (47%-72%). Metastatic sites: regional lymph nodes (sublumbar), lungs, spleen, bone (appendicular and axial skeleton), pancreas, heart, and mediastinum.Surgery: Aggressive saline diuresis ± diuretic therapy may be required prior to surgery if hypercalcemic with renal failure. Wide local resection: Resection of < 50% of anal sphincter will cause transient but not permanent fecal incontinence. Complete resection often difficult due to proximity to rectum and poor definition of perianal areaRecurrent disease difficult to resect. Exploratory celiotomy and sublumbar lymphadenectomy: Sublumbar lymph nodes can be resected in approximately 50% of cases. Resectability cannot be determined preoperatively and large sublumbar nodes do not preclude resection. Sublumbar lymph nodes can either be invasive or easily removedCastration has no benefit. 10% complication rate associated with anal sac resection including intraoperative hemorrhage, infection, fecal or urinary incontinence, hypocalcemia, tenesmus, and perianal fistula formation. (Source: VSSO https://vsso.org/anal-sac-tumors#biologic_behavior).
This a 7 yo/s, mixed breed female dog, with previous sublombar US guided FNA, with a perineal right side mass. Surgery was wide, clean margins, all sublombar lnn were exised, good recovery, epidural block for superior intraop. and postop. analgesia and still enjoying life 5 months after surgery. Surgery tips: Iliac lnn. dissection is a combination of digital, blunt and very rare sharp dissection, proximity to large arteries makes it even more challenging.