Salivary gland adenocarcinoma

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Histological appearance of a salivary gland adenocarcinoma

Salivary gland adenomacarcinomas are a relatively rare malignant neoplasia of the canine salivary gland.

These tumors usually develop within the salivary gland, usually the mandibular, parotid and zygomatic gland[1].

They are metastatic in nature, commonly involving regional lymph nodes, regional bone, with hematopoietic dissemination to the lungs.

Variant forms have been reported, such as salivary gland basal cell adenocarcinoma[2].

Older dogs are usually affected and clinical signs include varying amounts of oral pain, dysphagia, painful swelling, often in the submandibular region, halitosis and exophthalmos. Less common signs include sudden onset blindness due to ocular metastases[3].

Diagnosis requires histological analysis of biopsy material, usually by fine needle aspiration[4]. Clinical staging of tumors is a good indicator of survival time.

A differential diagnosis would include sialadenitis, sialolithiasis, sialocoele, squamous cell carcinoma, salivary gland adenoma[5], osteosarcoma, mast cell tumor and hemangiopericytoma.

Excisional sialoadenectomy with wide-margins is usually curative, but a rostral mandibulectomy or total hemimandibulectomy may be required with aggressive metastatic cases. Chemotherapy is indicated in most cases, usually doxorubicin, but post-operative orthovoltage radiation therapy has also be trialled[6].

Prognosis is guarded, but survival times of 1 - 2 years have been reported[7].

References

  1. Buyukmihci N et al (1975) Exophthalmos secondary to zygomatic adenocarcinoma in a dog. J Am Vet Med Assoc 167(2):162-165
  2. Sozmen M et al (2003) Salivary gland basal cell adenocarcinoma: a report of cases in a cat and two dogs. J Vet Med A Physiol Pathol Clin Med 50(8):399-401
  3. Habin DJ & Else RW (1995) Parotid salivary gland adenocarcinoma with bilateral ocular and osseous metastases in a dog. J Small Anim Pract 36(10):445-449
  4. Militerno G et al (2005) Cytological diagnosis of mandibular salivary gland adenocarcinoma in a dog. J Vet Med A Physiol Pathol Clin Med 52(10):514-516
  5. Smrkovski OA et al (2006) Carcinoma ex pleomorphic adenoma with sebaceous differentiation in the mandibular salivary gland of a dog. Vet Pathol 43(3):374-377
  6. Evans SM & Thrall DE (1983) Postoperative orthovoltage radiation therapy of parotid salivary gland adenocarcinoma in three dogs. J Am Vet Med Assoc 182(9):993-994
  7. Hammer A et al (2001) Salivary gland neoplasia in the dog and cat: survival times and prognostic factors. J Am Anim Hosp Assoc 37(5):478-482