Vet360 Vet 360 Vol 04 Issue 1 February 2017 | Page 21

DERMATOLOGY
PROGNOSIS It is important to treat according to the stage presented :
Primary Tumour : T0 = no tumour T in situ = Pre-invasive carcinoma ( scale , crust ) T1 = tumour < 2cm diameter , superficial or exophytic T2 = tumour 2 – 5 cm diameter , OR with minimal invasion irrespective of size T3 = tumour > 5cm diameter , or with invasion of subcutis irrespective of size T4 = invading fascial , muscle , bone or cartilage , regardless of size
Regional lymph nodes :
N0
=
no involvement
N1
=
lymphnodeinvolvement
Distant metastasis :
M0
=
no metastasis
M1
=
Íevidence of metastasis
Ulceration of the primary tumour is associated with a biologically more aggressive lesion and a poorer prognosis . It is not known why ulcerated primaries have a more aggressive biologic nature . It is not likely due to underestimation of the thickness due to the ulcer crater . Ulcerated lesions tend to be thicker and have a nodular growth pattern , but the increased thickness does not account for the poorer prognosis . However , the depth or width of surface ulceration has been significantly correlated with survival . Other histologic prognosticators include the mitotic indices , whirling and the presence or absence of lymphatic or blood vessel invasion are relevant to prognosis .
Tumours in situ look like nothing more than scaly , scabby skin and offer another earlier warning sign , the best opportunity for cure , and are a “ wake up call ”. My preference for this is to use immunotherapy with imiquimod cream , or photodynamic therapy for T in situ and T1 tumours .
T2 tumours which are large but NON invasive ( T2 large ) also respond well to PDT or radiotherapy , but those that are T2 invasive require surgery or aggressive PDT ( only to 5mm depth maximum ). Once it gets to T2 invasive or T3 +, cure rates using any technique drop to below 40 % ( from > 85 %) so teach your pet owners about skin cancer and early aggressive intervention from the first vaccination !
T3 and T1-4N /( any ) M0 / 1 must be referred to a specialist for management . I see huge disasters when GPs approach these with surgery . Dogs are disfigured and then referred when they could have kept penises , mobility or faces with a proper approach from the beginning . An integrated approach using multiple modalities and an understanding of tissue tolerances , treatment sequencing and proper patient surveillance are beyond the scope of general practice . Managing such a patient is often possible , but is an 8 – 20 week process .
More extensive tumours may require additional surgery , chemotherapy or radiation to achieve good results . Their main importance is that they recur because skin of the ventral abdomen , ears or nose have been damaged . ( fig 3 ) Cutting out squamous cell carcinomas can be like the little Dutch boy plugging the hole in the dyke with a finger – another often just pops up elsewhere .
Recurrent SCC may require specialist attention to get under control or cure . In any event , thoracic radiographs should be performed . SCC of the feet ( pedal SCC ) is far more aggressive and spreads to the lungs earlier than other SCC of the skin , so always attend to any non-healing wound or lump of > 1 week ’ s duration by having it checked using histopathology .
Treatment Photodynamic Therapy ( PDT ) ( fig 4 ) is a technique using the application or injection of photosensitising
Figure 1 . White cat with nasal SCC – this is the earliest stage – the presence of discharge and slight scaling around the nose and eyelids . If treated appropriately at this stage , the prognosis for cure is close to 100 %
Figure 2 . UV suit – UV-resistant suits ( obtained from Dr Georgina Crewe ), protect the healthy or precancerous skin and are an essential part of post-treatment management
Issue 06 | FEBRUARY 2017 | 21