Page 528 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

506 PART IV Specific Malignancies in the Small Animal Patient

masses, and endoscopic brushings of masses often yield suffi- debulk an epiglottic CSA and a solid tracheal osteochondroma
cient material for a cytologic diagnosis and immediate treatment in dogs. 246,247 Similarly, an endoscopically guided wire snare has
248
been used to debulk tracheal carcinomas in three cats.
(Fig. 24.11). Alternatively, tiny grab biopsies can be obtained
Surgical
VetBooks.ir through the instrument port for histopathology. 236 Care needs debulking followed by cryotherapy has been described to treat an
intratracheal adenoma in a cat.
to be taken with larger-bore scopes as extubation must be per-
249
formed in patients that may already suffer from respiratory Palliative stenting of malignant tracheal obstructions should
compromise. result in improvement in clinical signs in both dogs and cats.
Excisional biopsy (intralesional or marginal excision, or resec- Endoluminal stents, such as stainless-steel self-expanding metallic
tion and anastomosis) can be performed to obtain a diagnosis if stents, are placed minimally invasively under fluoroscopic guid-
earlier attempts at diagnosis have been unsuccessful. ance in anesthetized patients, and the procedure is rapid and low
risk. Long sections of trachea that could not be resected surgically
Therapy can be stented open with a stent greater than 2 cm longer than the
tracheal segment affected. 238,250 Potential complications of stent-
The relative infrequency and sporadic nature of laryngo-tracheal ing in dogs and cats include stent migration, fracture, granula-
tumors mean definitive treatment guidelines are lacking. Rec- tion tissue formation, coughing, tumor growing through the stent
ommendations are extrapolated from case reports, case series, or open-weave, pneumonia, and death. 251
oncologic principles of treating similar tumors in other locations. Chemotherapy and/or RT are primarily reserved for round cell
tumors of the trachea, especially lymphoma.
Larynx
Prognosis
Tube tracheostomy is a short-term measure to provide relief of
obstructive symptoms by providing airflow bypass and can be sur- Surgical removal of laryngeal cysts should be curative with no
gically converted to a tracheostomy to allow time for therapies, reported long-term effect on function. 213 Likewise, benign osteo-
such as chemotherapy or RT, to have an effect. chondromas in young dogs have an excellent prognosis after
Small lesions may be removed by mucosal resection or par- surgical resection. Intraoral diode laser total epiglottectomy for
tial laryngectomy through a transoral, ventral, or lateral laryngeal a laryngeal CSA resulted in a clinically normal dog 12 months
approach. 213,242,243 Larger lesions may require total laryngectomy postoperatively without any respiratory or digestive problem. 246
incorporating a permanent tracheostomy, but this has been rarely Another dog with a low-grade laryngeal CSA was still symptom
described in dogs. 215,244 External beam RT can be used to treat free 12 months after surgical resection involving ventral laryngot-
radiosensitive tumors (e.g., lymphoma), but few reports exist. omy and unilateral arytenoidectomy. 243 Three dogs with tracheal
CSA underwent surgical excision, with two dogs having no recur-
Trachea rence. 207 One dog had local recurrence at 3 months; the recur-
rent disease was surgically resected, and the dog survived a further
Surgical removal of the affected tracheal section is most likely to 8 months after the second excision. 207 Endoscopic removal of a
result in the longest disease-free intervals (DFIs) for solid tumors, bronchial carcinoma in one dog resulted in suspected local recur-
although tracheal resection and anastomosis is a complex surgical rence with respiratory difficulties 1 month postoperatively. 245
procedure, especially if involving the intrathoracic trachea. Com- Macroscopic invasion of the trachea by thyroid carcinoma has
plications include dehiscence, tracheal stenosis, pneumothorax, been shown to be a significant negative predictor for DFI; this
and laryngeal paralysis. 244 is seen in up to 24% of dogs with differentiated follicular cell
Endoscopic electrosurgical removal of a bronchial carcinoma in thyroid carcinomas with a median survival time (MST) of 2.5
the right mainstem bronchus has been described in a cocker span- months. 240
iel, 245 and a surgical diode laser has been used to endoscopically The prognosis for cats with tracheal carcinomas is poor as most
historically have been euthanized immediately after or within a
few days of diagnosis due to poor quality of life and rapid progres-
sion of disease. It is possible intraluminal stenting may improve
this outcome in the future as this modality becomes more widely
available.
Aggressive management in cats with solid laryngeal and tra-
cheal tumors, including combinations of surgical resection, RT,
and chemotherapy, have resulted in MSTs of 4 to 5 months with
<10% of cats alive at 1 year. 209 More favorable prognoses with
durable remission and survival times (STs) can be expected in
cats with laryngeal and tracheal lymphoma after RT, chemother-
apy, or combinations of these modalities; the reader is referred
to Chapter 33B for a more thorough discussion. One cat with
laryngeal SCC was treated with prednisolone and had a ST of
180 days. 230 A combination of local excision, RT, and melphalan
and prednisolone was successful in long-term control of a feline
laryngeal plasmacytoma. 216 Permanent tracheostomies in five cats
• Fig. 24.11 Video tracheoscopy has significantly improved the ability to
both diagnose and treat luminal masses in dogs and cats. This intraluminal with laryngeal carcinoma resulted in STs of 2 to 281 days, with
tracheal mass was diagnosed by brush cytology as a poorly differentiated two cats dying from tracheostomy occlusion and three cats from
round cell tumor. progressive disease. 252