Veterinary Society of
Surgical Oncology

GENERAL CONSIDERATIONS

General Considerations

  • mean age 11.3 years, with 90% cats > 8 years
  • malignant tumors are more common
  • LSA is most common although ADC and SCC also reported
  • LSA may present as a diffuse thickening of laryngeal mucosa or localized mass

Clinical Features

  • clinical signs: voice change, respiratory noise or distress with obstruction, exercise intolerance, dysphagia, and pain with inflammation and ulceration
  • diagnosis: ultrasound, survey radiographs, and biopsy under direct endoscopic visualization
  • DDx: inflammatory polyps and laryngeal cysts

TREATMENT

General Considerations

  • benign tumors and cysts can be removed while preserving function although more radical procedures required for malignant tumors such as permanent tracheostomy and complete laryngectomy
  • partial or complete laryngectomy is indicated for proliferative (i.e., granulomatous laryngitis) and neoplastic diseases
  • temporary tracheostomy may be required to permit resection
  • other options include radiation therapy and chemotherapy depending on tumor type and extent

Total Laryngectomy

  • total laryngectomy is indicated for tumors with bilateral laryngeal involvement
  • ventral midline cervical incision
  • traction sutures are placed around the 4th tracheal ring
  • trachea is transected caudal to the cricoid cartilage
  • sterile endotracheal tube is placed into the distal trachea and used to maintain general anesthesia
  • laryngeal attachments of the thyropharyngeal, cricopharyngeal, sternothyroid, and thyrohyoid muscles are transected
  • sternohyoid muscle is preserved
  • caudal aspect of the larynx is elevated and mobilized free of all attachments
  • sensory and motor nerves to pharyngeal mucosa and muscles and cranial esophagus are preserved to maintain normal swallowing ability
  • mucosa is incised at the rostral edge of the larynx and the entire larynx, including the epiglottis, is removed
  • pharyngeal mucosa is closed with a continuous inverting pattern of 3-0 absorbable suture material
  • transected ends of the thyropharyngeal and cricopharyngeal muscles are sutured together ventral to the pharynx and esophagus
  • proximal segment of the trachea is exteriorized
  • sternohyoid muscle is sutured to the trachea with interrupted sutures to maintain the trachea in a ventral position
  • excess subcutaneous tissue and skin are removed from the stoma site to prevent occlusion of the tracheostomy
  • elliptical skin incision is made 25%-30% larger than the trachea
  • subcutaneous tissue is sutured to the tracheal wall
  • skin is sutured to the tracheal mucosa with 3-0 or 4-0 absorbable suture material in an interrupted pattern

Rotatory Door Myocutaneous Flap

  • rotatory door myocutaneous flap was developed to bring vascularized epidermis into the laryngeal defect
  • island flap is based on the sternohyoid muscle with the dermis sutured to the mucosa
  • ventral midline cervical skin incision forms the medial edge of the myocutaneous flap
  • skin is not separated from the sternohyoid muscle and cranial thyroid blood vessels are preserved
  • cutaneous segment of the myocutaneous flap is depilated by shaving the epidermis down to the dermis
  • adequate dermal shaving prevents regrowth of hair and subsequent dermal scarring supports the graft
  • exposed dermal surface is covered by squamous or respiratory epithelium

Segmental Hemilaryngectomy

  • indication: small tumors involving the vocal cord and adjacent superficial tissues
  • ventral midline laryngotomy
  • tumor extent and margins are assessed
  • standard vocal cordectomy is performed if the tumor is localized to the vocal cord
  • mucosal incisions are deepened through full-thickness laryngeal cartilage if tumor involvement is more extensive
  • mucosal and cartilage defect is repaired primarily or filled with free tissue implants
  • free tissue implants include costal cartilage, buccal mucosa, and thyroid cartilage
  • free tissue implants are only used when the majority of the thyroid and arytenoid cartilages are resected
  • free tissue implants are sutured to the remaining cartilage with 3-0 or 4-0 monofilament absorbable suture material on a cutting needle
  • strap muscles and subcutaneous tissue are used to support the external aspect of the free tissue implant

Augmented Myomucosal Flap

General Considerations

  • augmented myomucosal flap was developed to repair laryngotracheal resection in 2 stages

Stage 1

  • ventral midline cervical incision
  • free buccal mucosal graft is used to cover the planned defect
  • porous high-density polyethylene (0.85 mm thick, average pore size > 150 μm, and pore volume 50%) is sutured over the free buccal mucosal graft
  • sternohyoid muscle, with preservation of cranial and caudal attachments, is mobilized and sutured over the free buccal mucosal graft and polyethylene

Stage 2

  • composite graft is released
  • laryngotracheal resection is performed as planned for tumor excision
  • laryngotracheal defect is repaired with the composite graft
  • polyethylene does not need to be fully covered by mucosa at the time of reconstruction as the polyethylene will be infiltrated by granulation tissue and rapidly epithelialized
  • temporary tracheostomy is performed distal to the resection site and maintained until healing and confirmation of airway patency

Prognosis

  • rhabdomyoma: most dogs will live > 1 year and are considered cured
  • malignant laryngeal tumors are rare tumors which are not frequently treated hence data not available

LARYNGEAL TUMORS

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