+ Biologic Behavior

  • Canine tongue tumors are uncommon and account for 4% of all oropharyngeal tumors in dogs
  • SCC is the most common tongue tumor (50%)
  • White dogs are predisposed to tongue SCC
  • Grading system based on degree of differentiation, degree of keratinization, mitotic rate, tissue invasion, vascular invasion, pleomorphism, and scirrhous reaction
  • Other types of tongue tumors include granular cell myoblastoma, malignant melanoma, MCT, FSA, ADC (salivary duct or ectopic thyroid origin), neurofibrosarcoma, leiomyosarcoma, HSA and hemangioma, rhabdomyoma and rhabdomyosarcoma, myxoma, and lipoma
  • Granular cell myoblastomas are invasive and large
  • However, local control rate following surgery > 80% and metastasis is rare
  • Malignant melanoma is associated with a local control rate of 80% and metastatic rate < 50%
  • 54% of canine tongue tumors are located in the midline or bilaterally symmetrical
  • Non-neoplastic tongue lesions include eosinophilic granuloma (cat) and calcinosis circumscripta (cats and dogs)

+ Diagnosis

  • Ultrasonography is useful in delineating margins of lingual mass
  • Wedge incisional biopsy closed with horizontal mattress sutures
  • Regional lymph node FNA for staging purposes

+ Treatment

  • Partial glossectomy of 40%-60% tongue if tumor is confined to the lateral or rostral half of the tongue
  • However, 33%-100% subtotal glossectomy has following either trauma or surgery has been reported in 5 dogs with minimal postoperative problems (ptyalism in 1 dog)
  • E-tube or G-tube feeding is required postoperatively if > 50% partial glossectomy
  • ± radiation therapy if inoperable or metastatic to the regional lymph nodes

+ Prognosis

  • Prognosis depends on site, type, and grade of tumor:
  • MST 16 months for grade I SCC
  • MST 4 months for grade II SCC
  • MST 3 months for grade III SCC
  • Surgery or radiation therapy for 10 dogs with glossal SCC: 12-month survival rate 50% with complete histologic resection and 60%-80% for complete histologic resection with low-grade histology