Head and Neck Tumours. Pathology, Pathophysiology, Clinical Presentation and Treatment

Transcription

1 Head and Neck Tumurs Pathlgy, Pathphysilgy, Clinical Presentatin and Treatment David J. Argyle BVMS PhD DECVIM-CA (Onclgy) FRSE MRCVS William Dick Prfessr f Veterinary Clinical Studies and Head f Schl. Ryal (Dick) Schl f Veterinary Studies and Rslin Institute The University f Edinburgh Easter Bush, Midlthian EH25 9RG Intrductin Head and neck cancers in cats represent a diverse grup f tumur types that can affect a diverse range f structures. Cmplicating this, is the fact that a tumur f a particular histitype can smetimes behave different bilgically depending n lcatin (the classical example being Squamus carcinma). Fr simplicity, I will divide this synpsis by anatmical lcatin. Orpharyngeal Tumurs Intrductin Oral cancer is frequently encuntered in the feline and canine patient. Dgs are mre frequently affected than cats with ral tumurs accunting fr 6% f canine cancer and 3% f feline cancer. The mst cmmn ral tumurs in dgs are malignant melanma, squamus cell carcinma, fibrsarcma and acanthmatus amelblastma. In cats squamus cell carcinma is by far the mst cmmnly diagnsed ral tumur, fllwed by ral fibrsarcma. Diagnstic Apprach And Staging The majrity f cases will present with a nted ral mass, hwever ral lesins can ften be missed by wners, especially thse lcated caudally. Typical clinical signs include halitsis, increased salivatin, dysphagia, lse teeth, weight lss, pain n pening the muth and less cmmnly exphthalms r facial asymmetry. N specific paraneplastic cnditins are assciated with ral tumurs. The diagnstic wrk up f any dg r cat presenting with an ral mass shuld include a thrugh histry and physical examinatin fllwed by determinatin f the diagnsis and staging. A diagnsis in the case f ral tumurs is typically via histpathlgy requiring a wide incisinal bipsy f the lesin under general anaesthesia. Initially cytlgy samples can be undertaken hwever given the cmmn secndary inflammatin, infectin and necrsis f ral lesins these can ften be nn-diagnstic. Oral lesins typically have a vast bld supply and preparatin fr adequate haemstasis shuld be cnsidered prir t bipsy. The use f electrcaudery can distrt the specimen and shuld nly be used fr haemstasis fllwing blade incisin r punch bipsy. Bipsies shuld always be taken frm within the ral cavity and nt via verlying dermis t avid seeding f tumur cells t nrmal skin. Curative-intent resectin fr small lesins (especially thse f the labial mucsa) may be cnsidered at the time f initial wrk up, hwever excisinal bipsy f mre extensive disease is nt recmmended. The general anaesthesia will apart frm facilitating a bipsy, firstly allw a thrugh ral examinatin. Clse inspectin f the pharynx, tnsils and hard palate shuld be undertaken as well as the grss margins f the lesin itself. Secndarily the pprtunity t undertake ral radigraphs r a Cmputed Tmgraphy (CT) scan f

2 the head shuld be undertaken t assess fr micrscpic disease extent. A CT scan allws fr greater detail and can serve t analyse mre precisely the lcatin and extent f the mass as well as underlying bne lysis. Fllwing advanced imaging surgical resectibility and discussin f best surgical apprach as well as likelihd f btaining wide surgical margins can be interpreted. Additinally cntrast uptake in the draining lymph ndes can be assessed. Anther advantage f a CT scan in the initial wrk up is the use f the images fr raditherapy treatment field planning fr cases where surgical resectin is nt apprpriate r is declined by the wner. Further staging shuld rutinely include aspiratin f the draining mandibular lymph nde if palpable (even if cnsidered nrmal n palpatin) and aspiratin f the tnsils shuld they appear grssly abnrmal. Reginal lymph ndes include the mandibular, partid and medial retrpharyngeal, hwever generally nly the mandibular ndes are palpable. Thracic cavity imaging is essential t assess fr distant metastasis via either three view thracic radigraphs r extensin f the CT thrugh the thracic cavity. The Wrld Health Organisatin s (WHO) clinical staging system fr ral tumurs in dgs as utlined in table 1, shuld be cnsidered in each case as the clinical stage f disease can be prgnstic fr ral tumurs (especially in the case f malignant melanma). Oral malignancies are typically lcally aggressive with a lw t intermediate metastatic ptential (apart frm malignant melanma). They typically ccur in lder animals >8 years ld and all cmmnly cause bne lysis. Dgs previusly dcumented as being at an increased risk f develping ral tumurs include the ccker spaniel, German shepherd dg, German shrthaired pinter, weimaraner, glden retriever, Grdn setter, miniature pdle, chw chw and the bxer. Surgery and raditherapy are the mainstays f therapy fr any ral tumur. The extent f the surgical apprach will be dictated by the lcatin and size f the lesin. The expectatin that in mst cases bne resectin will be necessary shuld be utlined t the wners t allw fr increased lcal tumur cntrl. The functinal and csmetic utcme fr mst patients fllwing mandibuletmy (segmental r hemi), maxillectectmy (segmental) r rbitectmy is generally very gd and wners satisfactin deemed t be high. With mst ral tumurs 2cm margins are required fr cnsideratin f reasnable lcal cntrl. This can be very challenging in the case f caudally lcated tumurs r tumurs which breach the midline f the palate. Raditherapy can be instigated as a primary therapy, as a curative intent prtcl r a palliative therapy, r as an adjunct t incmplete r marginal surgical excisin f an ral tumur. Here cnsideratin f the bilgical activity f the tumur type and estimatin f the respnsiveness f the tumur either in the grss disease r micrscpic disease setting shuld be cnsidered in rder t determine an apprpriate treatment prtcl fr each patient. Canine Oral Tumurs Malignant Melanma Malignant melanma is the mst cmmn ral tumur affecting dgs, accunting fr 30-40% f ral malignancies. Typically ccurring in dgs ver 10 years ld and small dg breeds especially the ccker spaniel, are ver represented, as well as dgs with darkly pigmented mucsa. The mass can ccur at any ral lcatin, hwever in rder f decreasing frequency they are fund n the gingiva, lips, tngue and hard palate. Apprximately 2/3 are said t be pigmented and 1/3 amelantic, they are cmmnly ulcerated and frequently have bne invlvement. The histpathlgy f an ral melanma can be cnfusing and they can ften be misdiagnsed as prly differentiated sarcmas r carcinmas. Melan A is an immunhistchemical marker used as a melanma specific marker, hwever its sensitivity drps with increasing degrees f differentiatin.

3 These tumurs are lcally aggressive and have a high metastatic ptential. The typical sites f metastasis include the reginal lymph ndes (up t 74%) and then the lungs (up t 67%). The WHO staging system fr canine malignant melanma is prgnstic with tumur size being f mst relevance. The metastatic rate is size, site and stage dependent. Other pr prgnstic factrs include incmplete surgical margins, lcatin (caudal mandible and rstral maxilla), mittic index >3, bne lysis, and mre recently dcumented the ki67 value. Squamus Cell Carcinma Squamus cell carcinma (SCC) is the secnd mst cmmn ral tumur in dgs, accunting fr 17-25% f cases. Tw separate disease entities shuld be cnsidered, tnsillar SCC and nn tnsillar SCC. The verall prgnsis fr nn tnsillar SCC is gd especially fr small and rstrally lcated lesins. These tumurs are typically lcally aggressive frequently causing bne lysis, but cnsidered t have a lw metastatic ptential. Reginal lymph nde metastatic disease is reprted as up t 10% and distant metastatic disease t the lungs reprted in 3 t 36% f cases (1). Tnsillar SCC has a much higher metastatic ptential; up t 77% f cases will have reginal metastatic develpment and 42-63% distant metastasis. Here frequent lcal tumur recurrence fllwing surgical r radiatin therapy is cmmn. Fibrsarcma Oral fibrsarcma (FSA) is the third mst cmmn ral tumur in dgs. This tumur will in many cases have a very benign histpathlgy and can be smetimes misdiagnsed as nn-neplastic. Hwever it will cmmnly shw an extremely aggressive bilgical behaviur grwing rapidly and causing severe bne destructin and facial defrmity. This subset f ral fibrsarcmas is ften referred t as bilgically high grade, histlgically lw grade. These tumurs have a predilectin fr the hard palate and maxilla and while typically being very lcally aggressive metastasize t the reginal lymph ndes and lungs in less than 30% f cases. Once again the size and lcatin f the tumur are prgnstic. Multimdality therapy utilising bth surgery and radiatin therapy is cnsidered standard f care fr these patients. Histrically when surgery is utilised alne the ne year survival rates have been said t typically nt exceed 1 year, hwever a mre recent publicatin has utlined mre favurable lcal cntrl and survival times (Overall survival 24.8 mnths) than previus reprts. This may be due t advancing surgical techniques as well as the increased use f CT imaging prir t surgical resectin. The gal f surgical excisin when planning resectin f an ral FSA shuld be t btain the widest margins pssible, hwever surgical excisin shuld still be cnsidered even when 2cm margins are nt expected. Radiatin therapy t a large tumur vlume is cnsidered less ideal and this tumur is cnsidered in the grss disease setting t be relatively radiatin resistant. Outcmes are imprved where surgery and raditherapy are used in cmbinatin. With a generally recgnised lw metastatic rate the rle f chemtherapy here has nt been fully identified, the fcus shuld remain n lcal disease cntrl. Acanthmatus Amelblastma Canine acanthmatus amelblastma (CAA) is characterised as a benign dtgenic tumur r epulis. The term epulis is a descriptive term applied t expansile gingival lesins. Odntgenic tumurs are generally cnsidered rare and there has been much cnfusin regarding their nmenclature and rigin as well as ther reactive lesins f the gingiva. The acanthmatus epulis has micrscpic

4 features in cmmn with human amelblastma. Hwever its clinically invasive nature with cmmn destructin f underlying bne (unlike ther dntgenic tumurs) is similar t the human intrasseus amelblastma. The tumur is nw termed CAA because it is cnsidered its wn entity with n precise human equivalent. CAA mst cmmnly affects the rstral mandible and a glden retrievers, akitas, ccker spaniels and Shetland sheepdgs are verrepresented breeds (1, 10). The typical appearance is cauliflwer like, red and ulcerated. While cnsidered lcally aggressive the tumurs have nt been knwn t metastasize and hence lcal tumur cntrl is the mainstay f therapy. FELINE ORAL TUMOURS Squamus Cell Carcinma SCC is the mst cmmn ral tumur f cats accunting fr apprximately 65% f tumurs seen. It can arise frm any ral mucsal surface including the sublingual regin the tnsils and the pharynx. The tumur is very lcally aggressive and cmmnly causes underlying bne lysis. The reginal lymph nde and distant metastatic rate is lw and estimated at 10%. Cats that wear a flea cllar are at 5 times the risk, additinal risk factrs include a high canned fd intake, canned fish and tbacc smke within the envirnment may have a rle in the pathgenesis f the disease. The average age f cats affected is years, any ral lesin in an lder cat shuld be bipsied prmptly as early diagnsis f may imprve the prgnsis. Many cats will present because the wners have nted an ral mass and the mst cmmn clinical signs include ptyalism, halitsis and in sme cases dysphagia. Staging shuld include as fr canine ral tumur cytlgy f the reginal mandibular lymph nde and three view thracic radigraphs. While ral radigraphs can be helpful and may be reasnable t determine underlying bne lysis, CT imaging allws fr greater accuracy f bne invlvement and shuld be undertaken in all cases where aggressive therapy is being cnsidered. While surgery and radiatin therapy can be undertaken the median survival time is shrt with survival times ver 3 mnths uncmmn and a ne year survival rate f less than 10%. Hwever the prgnsis is ptentially imprved fr thse patients with small and rstrally lcated lesin where wide surgical excisin can be undertaken and/r adjuvant raditherapy emplyed. Resectin f the mandible plus curative intent raditherapy gives a median survival f 14 mnths. In the majrity f cases surgery alne des nt ffer a significantly extended survival time t untreated cats due t the fact that the disease is s lcally invasive and wide margins are typically unachievable. Likewise palliative raditherapy is nt prven t imprve survival significantly ver untreated cases. N chemtherapy t date has been shwn t be effective in the treatment f these cases. Histrically results were imprved with the cmbinatin f raditherapy and radiatin sensitizers, hwever rapid recurrence was dcumented. A recently published paper has described an accelerated radiatin prtcl with cncurrent chemtherapy. Here cats received 14 fractins f 3.5 Gy fr a ttal f 49 Gy in a nine day perid while receiving cncurrent intravenus Carbplatin. The prtcl was intense but well tlerated with a median survival time f 169 days. Cats with disease f the tnsils r cheek had an increased survival time. Pain management and the cnsideratin f NSAID therapy, antibitic therapy as well as frequent quality f life assessment are crucial in the medical management f Feline Cutaneus SCC Accunts fr 15% f feline cutaneus tumurs

5 Often assciated with prly pigmented skin and UV expsure In cats, the mst cmmn areas fr SCC develpment are the nasal planum, the eyelids and the pinnae. Tumurs are lcally invasive but slw t metastasize. The tumur may be 'prductive' frming a papillary grwth with a cauliflwer like appearance, r 'ersive' frming a shallw ulcer with raised edges. In bth instances the lesin is frequently ulcerated, infected and assciated with a chrnic inflammatry infiltrate. It is nt uncmmn fr these tumurs t be dismissed as infective/inflammatry lesins n initial presentatin. Multifcal distributin f superficial lesins has been reprted in cats. This is referred t as multicentric SCC in situ r Bwen s disease. Bwen s disease is an unusual feline skin cnditin f unknwn rigin. Recently, papillmavirus antigen has been demnstrated in 45% f the feline skin lesins using immunhistchemical methds. Unlike slar induced SCC, Bwen s disease is fund in haired, pigmented areas f the skin and is unrelated t sunlight expsure. Lesins are cnfined t the epithelium with n breachment f the basement membrane. Lesins are crusty, easily epilated, painful and hemrrhagic. When excisin is pssible, recurrence has nt been reprted, hwever similar lesins ften develp at ther sites. Surgery: Fr tumurs f the pinnae, surgery (pinnectmy) ffers tumr cntrl fr >1.5 years Fr nasal planum tumurs, surgery can ffer gd lcal cntrl, but recmmend referral t a specialist, bard certified surgen fr best results. En blc resectin f lwer eyelid tumurs als ffers gd cntrl, but advise referral t a bard certified surgen. Crytherapy Aggressive crytherapy can ffer gd lcal cntrl fr tumurs f the pinnae and eyelid. Tumurs f the nasal planum appear t have a prer respnse. Raditherapy External beam raditherapy has demnstrated gd lcal cntrl fr lwer stage tumurs. Strntium-90 Plesitherapy has shwn efficacy fr superficial lesins Chemtherapy Intratumral administratin f carbplatin in a sesame il suspensin appears safe, practical and effective fr SCC f the nasal planum in cats Phtdynamic Therapy Benefit has been demnstrated nly in superficial tumurs f lw stage Nassinal tumurs in dgs Key Pints: Tumurs arise frm the nasal cavity and/r paranasal sinuses and are almst always malignant. Mst are adencartcinmas Older dgs are mst cmmnly affected, althugh dgs as yung as ne year have been reprted Medium and large breed dgs are predispsed

6 The mst cmmn malignant tumur types are carcinma, including adencarcinma, and sarcma, including fibrsarcma, chndrsarcma and stesarcma Less cmmn malignant tumurs include lymphma, mast cell tumur, lfactry neurblastma and thers. Benign tumurs rarely ccur but can include plyps and fibrmas. Malignant tumurs are lcally aggressive, ften causing destructin f bne. Tumurs can extend beynd the cribifrm plate int the calvarium. The rate f reginal and distant metastasis is lw at the time f diagnsis. Mst cmmn sites f metastasis include lymph nde and lungs. Therapy is aimed at lcal tumur cntrl r palliatin f clinical signs Paraneplastic syndrmes assciated with nasal tumurs are rare. Erythrcytsis and hypercalcemia have been reprted. Envirnmental factrs including tabacc smke and indr expsure t fssil fuel cmbustin prducts may be related t tumur develpment. Clinical Signs f Nassinal Tumrs Unilateral r bilateral nasal discharge: mucid, purulent, hemrrhagic, r any cmbinatin theref Epistaxis Nasal cngestin r stertrus breathing Sneezing Facial defrmity due t subcutaneus extensin f tumur Epiphra Exphthalmus Neurlgic signs including seizures, behavir change, and btundatin due t direct tumur extensin int the calvarium Halitsis Oral mass due t tumr extensin int the ral cavity Differential Diagnsis Fr Dgs With Clinical Signs Relating T The Nasal Cavity And Nasal Sinuses: Neplasia (see Histlgic Classificatin belw) Fungal rhinitis (Aspergillsis, Blastmycsis r Sprtrichsis ) Bacterial rhinitis Immune-mediated lymphplasmacytic rhinitis Cagulpathies Hypertensin Freign bdy Trauma Embrynic vestige (Rathke s clefts cyst) Diagnsis: If epistaxis is the nly nasal sign, cagulatin parameters (PT, PTT) and platelet cunt shuld be evaluated t rule ut a primary cagulpathy. In almst all cases f nassinal neplasia, a mass lesin is present in the nasal cavity

7 Imaging is necessary t lcalize the lesin and determine its extent Advanced imaging including cmputed tmgraphy (CT) r magnetic resnance imaging (MRI) is mre sensitive than radigraphy Histpathlgy is required fr definitive diagnsis Nasal bipsy techniques include nn-invasive and invasive methds (see table belw). T avid misdiagnsis, it is imprtant t keep in mind that nasal signs caused by a tumur may imprve temprarily with the use f antibitics, nn-steridal anti-inflammatry drugs r sterids. Nn-invasive Nasal Bipsy Techniques Nasal flushing Blind transnstril bipsy 1,2 Endscpy-guided fiberptic bipsy 1 Fine needle aspiratin r bipsy f facial defrmities Invasive Nasal Bipsy Techniques Surgical bipsy via rhintmy 1 Cagulatin parameters shuld be assessed prir t transnstril bipsy as bleeding frm the bipsy site is expected 2 Blind transnstril bipsy instruments shuld nt be intrduced further than the medial canthus f the eye t avid penetratin f the cribifrm plate Treatment and Prgnsis: Since the rate f metastasis is lw at the time f diagnsis, lcal therapy is indicated. Radiatin therapy is the treatment f chice. Surgery (rhintmy) alne results in rapid tumur re-grwth Palliative therapy: NSAIDS Feline Nassinal Tumurs Key Pints: Tumurs arise frm the nasal cavity and/r paranasal sinuses and are almst always malignant. Mst are adencartcinmas Clinical Signs f Nassinal Tumrs Unilateral r bilateral nasal discharge: mucid, purulent, hemrrhagic, r any cmbinatin theref Epistaxis Nasal cngestin r stertrus breathing Sneezing Facial defrmity due t subcutaneus extensin f tumur Epiphra Exphthalmus Neurlgic signs including seizures, behavir change, and btundatin due t direct tumur extensin int the calvarium Halitsis Oral mass due t tumur extensin int the ral cavity

8 Differential Diagnsis fr cats With Clinical Signs Relating T The Nasal Cavity And Nasal Sinuses: Neplasia (see Histlgic Classificatin belw) Bacterial rhinitis Immune-mediated lymphplasmacytic rhinitis Cagulpathies Hypertensin Freign bdy Trauma Diagnsis: If epistaxis is the nly nasal sign, cagulatin parameters (PT, PTT) and platelet cunt shuld be evaluated t rule ut a primary cagulpathy. In almst all cases f nassinal neplasia, a mass lesin is present in the nasal cavity Imaging is necessary t lcalize the lesin and determine its extent Advanced imaging including cmputed tmgraphy (CT) r magnetic resnance imaging (MRI) is mre sensitive than radigraphy Histpathlgy is required fr definitive diagnsis Nasal bipsy techniques include nn-invasive and invasive methds (see table belw). T avid misdiagnsis, it is imprtant t keep in mind that nasal signs caused by a tumur may imprve temprarily with the use f antibitics, nn-steridal anti-inflammatry drugs r sterids. Nn-invasive Nasal Bipsy Techniques Nasal flushing Blind transnstril bipsy 1,2 Endscpy-guided fiberptic bipsy 1 Fine needle aspiratin r bipsy f facial defrmities Invasive Nasal Bipsy Techniques Surgical bipsy via rhintmy 1 Cagulatin parameters shuld be assessed prir t transnstril bipsy as bleeding frm the bipsy site is expected 2 Blind transnstril bipsy instruments shuld nt be intrduced further than the medial canthus f the eye t avid penetratin f the cribifrm plate Treatment and Prgnsis: Since the rate f metastasis is lw at the time f diagnsis, lcal therapy is indicated. Radiatin therapy is the treatment f chice. Surgery (rhintmy) alne results in rapid tumur re-grwth Palliative therapy: NSAIDS Nassinal tumurs in cats: Key Pints: Less cmmn than in the dg Older cats are mst ften affected Malignant tumrs are mre cmmn than benign tumrs

9 Tumurs are lcally aggressive, ften causing destructin f bne. Tumurs can extend beynd the cribifrm plate int the calvarium. Mst cmmn tumur type is lymphma, fllwed by carcinma and adencarcinma Rhinitis can mimic neplasia in clinical signs and imaging findings Risk f metastasis is mderate t high fr lymphma, but lw fr carcinma Lack f clinical data regarding efficacy f treatment Cats with nassinal lymphma shuld be tested fr FeLV and FIV Thyrid Tumurs in Dgs Key Pints Accunt fr 1-4% f all tumurs in dgs 30-50% are benign, nn-functinal adenmas Adenmas are very small and are usually nt detected clinically (incidental finding at necrpsy) Mst clinically detected tumurs are classified as malignant. Age range f 9-11 years In rare cases, ectpic thyrid tissue can be affected 35-40% f dgs have visibly detectable metastatic disease at presentatin (lymph ndes and lungs) The treatment f chice is dictated by: Size f the mass Degree f invasin Cncurrent metastatic disease Evidence f thyrtxicsis Fr freely mveable, nn-invasive tumurs, surgical excisin is the treatment f chice, giving a median survival time f arund 3 years. Nn-resectable tumurs are managed with external beam radiatin. May be used in the neadjuvant setting t imprve a definitive surgery Can be used pst-peratively t treat minimal residual disease Used alne: shrink tumurs ver a 6-mnth perid giving very gd lcal cntrl. Dgs with grss metastatic disease Metastasis (even when detected visually), takes a lng time t becme clinical (smetimes 1-2 years) Surgery fr freely mbile tumurs r palliative raditherapy fr nnmbile tumurs is therefre still a reasnable ptin withut cmprmising patient quality f life. Is radiactive Idine ever indicated in canine thyrid tumurs? In humans 131 I is ften used pst-surgically t treat micrscpic disease. Experience in dgs is limited. The majr limiting factr in dgs is the high dse f 131 I required, as these tumurs d nt accumulate idine in the same way as functinal adenmas. Mst centres d nt have the facilities required (health and safety) t handle such dses.

10 Is chemtherapy indicated in the management f canine thyrid tumurs? Where surgery f raditherapy is nt a viable ptin, chemtherapy with either dxrubicin r carbplatin culd be cnsidered. Hwever, nly partial respnses shuld be expected and it must be cnsidered palliative nly. Where radiatin is nt available, chemtherapy may be cnsidered where surgical resectin has been perfrmed, but surgical margins demnstrate micrscpic disease. Chemtherapy can be cnsidered where there is grss metastatic disease. Hwever, disease prgressin in these cases is ften slw anyway. The beneficial effects f adding in chemtherapy are unprven. Large tumurs and bilateral tumurs have been shwn t have a greater metastatic ptential. Cnsequently adjunctive chemtherapy may be cnsidered fr tumurs abve 20-30cm 3 Feline Thyrid Tumurs Key Pints Hyperthyridism is the mst cmmn endcrinpathy in cats 70-75% f cases are caused by multindular adenmatus hyperplasia 20-25% are caused by slitary adenmas 1-3% are caused by malignant carcinmas Clinical Signs: Older cats > 8years Weight lss with plyphagia PUPD Vmiting and diarrhea Hyperactivity Tachycardia, heart murmur, gallp rhythm Pr cat Palpable gitre Diagnsis Clinical signs and histry Elevated serum ttal T4 (tt4) free T4 by equilibrium dialysis if tt4 in mid t high range but highly suspicius Dynamic testing rarely indicated Staging CBC, serum chemistry and urinalysis Thracic radigraphy, ECG, Echcardigraphy Bld pressure measurement +/- technetium scintigraphy t determine the extents f disease (uni r bilateral, ectpic) Medical Management:

11 Thiamazle (licensed in UK) r carbimazle Inhibit thyrid hrmne synthesis Used as: Sle treatment T stabilize a patient prir t thyridectmy During 131 I treatment Cats are mnitred using tt4 levels Side effects include vmiting and anrexia Nt effective fr carcinmas Surgical Management: Cats are managed medically (see abve) prir t surgery (fr arund 2 weeks). Intracapsular and extracapsular techniques are described Intracapsular methd preserves the adjacent parathyrid tissue, but the extracapsular technique is superir fr achieving adequate surgical excisin. Pst-perative cmplicatins include Laryngeal paralysis Hrner s syndrme Hypcalcaemia Hypthyridism Fr cats where surgery des nt reslve clinical signs cnsider: Lng-term medical management 131 I treatment 131 I Treatment Treatment f chice, especially where: Bilateral disease Ectpic thyrid tissue is affected Thyrid carcinma (higher dse ften required) Specialist facilities required Refer Ear Canal Tumurs f Dgs and Cats Key pints These are nt uncmmn tumurs in bth species, and may be assciated with chrnic inflammatin frm titis externa Clinical signs include chrnic irritatin, presence f a mass lesin, aural discharge, pain and an dr. In severe cases with middle r inner invlvement, patients may present with vestibular signs r Hrner s syndrme. The mst cmmn benign tumurs in bth species are: Inflammatry plyps Ceruminus adenmas Papillmas Basal cell tumurs The mst cmmn malignant tumurs are: Dgs Ceruminus gland adencarcinma Squamus cell carcinma Carcinma f undetermined rigin

12 Cats Ceruminus gland adencarcinma Squamus cell carcinma Therapy: Fr benign lesins, cnservative surgical resectin in bth species ffers a gd prgnsis. Fr malignant lesins, ear canal ablatin and lateral bulla stetmy shuld be cnsidered the treatment f chice. Prgnsis fr dgs is better than fr cats Lcal raditherapy may be cnsidered where incmplete resectin is achieved.