Difference between revisions of "Squamous Cell Carcinoma"
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Also Known As: '''''SCC''''' | Also Known As: '''''SCC''''' | ||
| − | =Introduction= | + | ==Introduction== |
[[Image:oral squamous cell carcinoma.jpg|right|thumb|200px|<center>'''Oral squamous cell carcinoma'''. Courtesy of T. Scase</center>]] | [[Image:oral squamous cell carcinoma.jpg|right|thumb|200px|<center>'''Oral squamous cell carcinoma'''. Courtesy of T. Scase</center>]] | ||
'''Squamous cell carcinomas (SCC)''' are '''malignant''' tumours commonly seen in the cat, dog, horse and cow. They are most likely to develop in '''non-pigmented areas''' of the skin as there is a known association between their development and exposure to '''UV light'''. The tumours are normally '''slow to metastasize''' but may be locally invasive. | '''Squamous cell carcinomas (SCC)''' are '''malignant''' tumours commonly seen in the cat, dog, horse and cow. They are most likely to develop in '''non-pigmented areas''' of the skin as there is a known association between their development and exposure to '''UV light'''. The tumours are normally '''slow to metastasize''' but may be locally invasive. | ||
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Histologially, the tumours are formed from '''epidermal cells''' with varying degrees of '''squamous cell differentiation'''. | Histologially, the tumours are formed from '''epidermal cells''' with varying degrees of '''squamous cell differentiation'''. | ||
| − | ==Cat== | + | ===Cat=== |
[[File:Feline actinic SCC.JPG|thumb|150px|right|'''Cat with actinic keratoses and eyelid SCC''' (Wikimedia Commons)]] | [[File:Feline actinic SCC.JPG|thumb|150px|right|'''Cat with actinic keratoses and eyelid SCC''' (Wikimedia Commons)]] | ||
| − | '''Cutaneous''' squamous cell carcinomas are common in '''white cats''', especially on the '''tips of the pinnae''', '''nasal planum''' and '''eyelid'''. '''Multiple''' tumours may develop '''simultaneously''' as the tissue has been exposed to the same level of ultraviolet damage. Often the appearance of '''acinitic keratosis''' precedes the appearance of the tumour. The lesions are normally '''crusted''', '''ulcerative''' and '''progress''' over time. They may begin very small and | + | '''Cutaneous''' squamous cell carcinomas are common in '''white cats''', especially on the '''tips of the pinnae''', '''nasal planum''' and '''eyelid'''. '''Multiple''' tumours may develop '''simultaneously''' as the tissue has been exposed to the same level of ultraviolet damage. Often the appearance of '''acinitic keratosis''' precedes the appearance of the tumour. The lesions are normally '''crusted''', '''ulcerative''' and '''progress''' over time. They may begin very small and are commonly mistaken for cat scratches, therefore it is essential that any 'scratch' that fail to heal is treated with suspicion and '''biopsied'''. Ideal treatment is radical '''excision'''. In the case of pinna SCC's, pinnectomy is indicated. |
SCC of the '''nasal cavity''' are reported. These normally originate from the nasal '''vestibule''' and cause clinical signs associated with airway obstruction and tissue necrosis. | SCC of the '''nasal cavity''' are reported. These normally originate from the nasal '''vestibule''' and cause clinical signs associated with airway obstruction and tissue necrosis. | ||
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Squamous cell carcinomas of the [[Oesophagus - Anatomy & Physiology|oesophagus]] are most notably seen in the cat, where the tumour tends to '''infiltrate''' around the oesophageal wall resulting in a “'''ring carcinoma'''”. The affected cat has progressive '''difficulty in eating''' and [[Deglutition|swallowing]]. Oesophageal SCC forms part of [[Upper Alimentary Tract Carcinoma Complex|upper alimentary tract carcinoma complex]]. | Squamous cell carcinomas of the [[Oesophagus - Anatomy & Physiology|oesophagus]] are most notably seen in the cat, where the tumour tends to '''infiltrate''' around the oesophageal wall resulting in a “'''ring carcinoma'''”. The affected cat has progressive '''difficulty in eating''' and [[Deglutition|swallowing]]. Oesophageal SCC forms part of [[Upper Alimentary Tract Carcinoma Complex|upper alimentary tract carcinoma complex]]. | ||
| − | ==Dog== | + | ===Dog=== |
'''Cutaneous''' SCC's are common in '''white breeds''' of dog such as the Boxer, Dalmation and English Bull Terrier. | '''Cutaneous''' SCC's are common in '''white breeds''' of dog such as the Boxer, Dalmation and English Bull Terrier. | ||
| − | ==Horse== | + | ===Horse=== |
'''Cutaneous''' SCC's are the second most common neoplasms in the horse. Contact with '''penile smegma''' is thought to be an a predisposing cause. They are most commonly located in the '''penile''' or '''clitoral''' regions and on '''non-pigmented''' skin. Lesions are '''progressive''' and potentially '''locally invasive'''. They may be '''ulcerative''' or '''proliferative''' and '''secondary infection''' is often present, producing a foul odour. Complete '''surgical excision''' is the gold standard treatment, but '''adjuncts''' may be required. Masses located around the eye may need prompt specialist treatment to save the eye. | '''Cutaneous''' SCC's are the second most common neoplasms in the horse. Contact with '''penile smegma''' is thought to be an a predisposing cause. They are most commonly located in the '''penile''' or '''clitoral''' regions and on '''non-pigmented''' skin. Lesions are '''progressive''' and potentially '''locally invasive'''. They may be '''ulcerative''' or '''proliferative''' and '''secondary infection''' is often present, producing a foul odour. Complete '''surgical excision''' is the gold standard treatment, but '''adjuncts''' may be required. Masses located around the eye may need prompt specialist treatment to save the eye. | ||
| − | SCC of the '''stomach''' is the most common gastric tumour in the horse. It has the appearance of a large '''cauliflower-like mass''' and affects the '''pars oesophagea'''. It metastasises and spreads | + | SCC of the '''stomach''' is the most common gastric tumour in the horse. It has the appearance of a large '''cauliflower-like mass''' and affects the '''pars oesophagea'''. It metastasises and spreads '''transcoelomically'''. |
Rarely SCC can form in the '''nasal cavity''' of the horse. These originate from the '''maxillary sinus''' and cause '''facial distortion''', '''tissue necrosis''' and '''airway obstruction'''. A '''serosanginous''' or '''mucopurulent''', '''odorous nasal discharge''' may be present. | Rarely SCC can form in the '''nasal cavity''' of the horse. These originate from the '''maxillary sinus''' and cause '''facial distortion''', '''tissue necrosis''' and '''airway obstruction'''. A '''serosanginous''' or '''mucopurulent''', '''odorous nasal discharge''' may be present. | ||
| − | ==Cow== | + | ===Cow=== |
As mentioned, squamous cell carcinomas are most likely to develop on '''non-pigmented areas of skin''' such as the '''eyelids'''. Additionally, there is thought to be an association between the '''ingestion of bracken fern carcinogens''' and the '''malignant transformation of papillomas''' to squamous cell carcinomas in cattle. | As mentioned, squamous cell carcinomas are most likely to develop on '''non-pigmented areas of skin''' such as the '''eyelids'''. Additionally, there is thought to be an association between the '''ingestion of bracken fern carcinogens''' and the '''malignant transformation of papillomas''' to squamous cell carcinomas in cattle. | ||
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Squamous cell carcinomas of the [[Oropharynx - Anatomy & Physiology|oropharynx]] in cattle are commonly seen as part of an [[Upper Alimentary Tract Carcinoma Complex|upper alimentary tract carcinoma complex]]. | Squamous cell carcinomas of the [[Oropharynx - Anatomy & Physiology|oropharynx]] in cattle are commonly seen as part of an [[Upper Alimentary Tract Carcinoma Complex|upper alimentary tract carcinoma complex]]. | ||
| − | =Diagnosis= | + | ==Diagnosis== |
| − | [[File:Well differentiated squamous cell carcinoma.jpg|thumb|right| | + | [[File:Well differentiated squamous cell carcinoma.jpg|thumb|right|200px|'''Well differentiated squamous cell carcinoma''' (Wikimedia Commons)]] |
FNA's should be performed as a first line diagnostic test on any suspicious mass. '''Cytology''' may show: | FNA's should be performed as a first line diagnostic test on any suspicious mass. '''Cytology''' may show: | ||
* Pleomorphic epithelial cells - these have a variable appearance from benign keratinized mature squames to epithelial cells with anisocytosis, basophilic cytoplasm and extensive vacuolation. | * Pleomorphic epithelial cells - these have a variable appearance from benign keratinized mature squames to epithelial cells with anisocytosis, basophilic cytoplasm and extensive vacuolation. | ||
* Binucleate cells, chromatin clumping and prominent nucleoli may be present | * Binucleate cells, chromatin clumping and prominent nucleoli may be present | ||
| − | |||
A '''biopsy''' should always be performed to confirm diagnosis. | A '''biopsy''' should always be performed to confirm diagnosis. | ||
| − | |||
'''Histopathological''' examination of a biopsy of the mass should reveal: | '''Histopathological''' examination of a biopsy of the mass should reveal: | ||
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* Central necrosis accompanied by high neutrophil numbers | * Central necrosis accompanied by high neutrophil numbers | ||
| − | =Treatment= | + | ==Treatment== |
Dependant on the site of neoplasia, treatment may involve '''debaulking/complete excisional surgery''', '''radiotherapy''', '''cryosurgery''', '''photodynamic therapy''' and '''hyperthermia'''. However '''complete surgical excision is the ideal'''. | Dependant on the site of neoplasia, treatment may involve '''debaulking/complete excisional surgery''', '''radiotherapy''', '''cryosurgery''', '''photodynamic therapy''' and '''hyperthermia'''. However '''complete surgical excision is the ideal'''. | ||
Although the metastatic rate of these tumours is normally slow, '''screening''' should be performed prior to the start of treatment. This involves '''radiography of the thorax''' and '''fine needle aspiration of local lymph nodes'''. | Although the metastatic rate of these tumours is normally slow, '''screening''' should be performed prior to the start of treatment. This involves '''radiography of the thorax''' and '''fine needle aspiration of local lymph nodes'''. | ||
| − | =Prognosis= | + | ==Prognosis== |
| − | [[Image:cowpap1.gif|right|thumb| | + | [[Image:cowpap1.gif|right|thumb|200px|<center>'''Papilloma and SCC of Epiglottis''' (Courtesy of Alun Williams (RVC))</center>]] |
The '''smaller''' the tumour is identification, the better the chance of successful removal and a '''good prognosis'''. As mentioned, these tumours are often locally invasive but '''slow to metastasise''', however the level of malignancy and therefore prognosis is often related to the '''location''' of the neoplasm. Those arising over the '''tonsil''' (squamous carcinoma of the tonsil or tonsillar carcinoma) are '''very malignant''', invading adjacent tissues and metastasising early. Squamous carcinomas of the '''tongue''' (especially in '''cats''') can also behave in a '''very malignant''' fashion. Those at more '''rostral''' sites, e.g. on the incisor gingivae, are '''less likely to metastasize''' early although they may be locally aggressive. They should be staged according to the '''World Health Organisation (WHO) system'''. | The '''smaller''' the tumour is identification, the better the chance of successful removal and a '''good prognosis'''. As mentioned, these tumours are often locally invasive but '''slow to metastasise''', however the level of malignancy and therefore prognosis is often related to the '''location''' of the neoplasm. Those arising over the '''tonsil''' (squamous carcinoma of the tonsil or tonsillar carcinoma) are '''very malignant''', invading adjacent tissues and metastasising early. Squamous carcinomas of the '''tongue''' (especially in '''cats''') can also behave in a '''very malignant''' fashion. Those at more '''rostral''' sites, e.g. on the incisor gingivae, are '''less likely to metastasize''' early although they may be locally aggressive. They should be staged according to the '''World Health Organisation (WHO) system'''. | ||
| − | =Prevention= | + | ==Prevention== |
Squamous cell carcinomas can be prevented by '''protecting the skin from ultraviolet light'''. This may be achieved using '''sunblocks''' or by keeping the animals '''indoors''' or in the '''shade'''. This is rarely practicable. | Squamous cell carcinomas can be prevented by '''protecting the skin from ultraviolet light'''. This may be achieved using '''sunblocks''' or by keeping the animals '''indoors''' or in the '''shade'''. This is rarely practicable. | ||
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}} | }} | ||
| − | =References= | + | ==References== |
Bond, Hendricks, Loeffler (2009) '''Veterinary Dermatology''' RVC Intergrated BVetMed Course, ''Royal Veterinary College'' | Bond, Hendricks, Loeffler (2009) '''Veterinary Dermatology''' RVC Intergrated BVetMed Course, ''Royal Veterinary College'' | ||
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| − | + | {{review}} | |
[[Category:Nasal Cavity - Hyperplastic/Neoplastic Pathology]] | [[Category:Nasal Cavity - Hyperplastic/Neoplastic Pathology]] | ||
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[[Category:Respiratory System - Hyperplastic/Neoplastic Pathology]] | [[Category:Respiratory System - Hyperplastic/Neoplastic Pathology]] | ||
[[Category:Neoplasia]] | [[Category:Neoplasia]] | ||
| − | [[Category: | + | [[Category:Expert Review]] |
| − | |||
Revision as of 16:38, 23 September 2011
Also Known As: SCC
Introduction
Squamous cell carcinomas (SCC) are malignant tumours commonly seen in the cat, dog, horse and cow. They are most likely to develop in non-pigmented areas of the skin as there is a known association between their development and exposure to UV light. The tumours are normally slow to metastasize but may be locally invasive.
There are two forms of the neoplasm:
- Proliferative — cauliflower-like lesions
- Ulcerative — ulcerative lesions
Histologially, the tumours are formed from epidermal cells with varying degrees of squamous cell differentiation.
Cat
Cutaneous squamous cell carcinomas are common in white cats, especially on the tips of the pinnae, nasal planum and eyelid. Multiple tumours may develop simultaneously as the tissue has been exposed to the same level of ultraviolet damage. Often the appearance of acinitic keratosis precedes the appearance of the tumour. The lesions are normally crusted, ulcerative and progress over time. They may begin very small and are commonly mistaken for cat scratches, therefore it is essential that any 'scratch' that fail to heal is treated with suspicion and biopsied. Ideal treatment is radical excision. In the case of pinna SCC's, pinnectomy is indicated.
SCC of the nasal cavity are reported. These normally originate from the nasal vestibule and cause clinical signs associated with airway obstruction and tissue necrosis.
Squamous cell carcinomas of the oesophagus are most notably seen in the cat, where the tumour tends to infiltrate around the oesophageal wall resulting in a “ring carcinoma”. The affected cat has progressive difficulty in eating and swallowing. Oesophageal SCC forms part of upper alimentary tract carcinoma complex.
Dog
Cutaneous SCC's are common in white breeds of dog such as the Boxer, Dalmation and English Bull Terrier.
Horse
Cutaneous SCC's are the second most common neoplasms in the horse. Contact with penile smegma is thought to be an a predisposing cause. They are most commonly located in the penile or clitoral regions and on non-pigmented skin. Lesions are progressive and potentially locally invasive. They may be ulcerative or proliferative and secondary infection is often present, producing a foul odour. Complete surgical excision is the gold standard treatment, but adjuncts may be required. Masses located around the eye may need prompt specialist treatment to save the eye.
SCC of the stomach is the most common gastric tumour in the horse. It has the appearance of a large cauliflower-like mass and affects the pars oesophagea. It metastasises and spreads transcoelomically.
Rarely SCC can form in the nasal cavity of the horse. These originate from the maxillary sinus and cause facial distortion, tissue necrosis and airway obstruction. A serosanginous or mucopurulent, odorous nasal discharge may be present.
Cow
As mentioned, squamous cell carcinomas are most likely to develop on non-pigmented areas of skin such as the eyelids. Additionally, there is thought to be an association between the ingestion of bracken fern carcinogens and the malignant transformation of papillomas to squamous cell carcinomas in cattle.
Squamous cell carcinomas of the oropharynx in cattle are commonly seen as part of an upper alimentary tract carcinoma complex.
Diagnosis
FNA's should be performed as a first line diagnostic test on any suspicious mass. Cytology may show:
- Pleomorphic epithelial cells - these have a variable appearance from benign keratinized mature squames to epithelial cells with anisocytosis, basophilic cytoplasm and extensive vacuolation.
- Binucleate cells, chromatin clumping and prominent nucleoli may be present
A biopsy should always be performed to confirm diagnosis.
Histopathological examination of a biopsy of the mass should reveal:
- Irregular cords or masses of epidermal cells entering the dermis
- Keratin pearls
- High mitotic rate
- Large nuclei with prominent nucleoli
- Central necrosis accompanied by high neutrophil numbers
Treatment
Dependant on the site of neoplasia, treatment may involve debaulking/complete excisional surgery, radiotherapy, cryosurgery, photodynamic therapy and hyperthermia. However complete surgical excision is the ideal.
Although the metastatic rate of these tumours is normally slow, screening should be performed prior to the start of treatment. This involves radiography of the thorax and fine needle aspiration of local lymph nodes.
Prognosis
The smaller the tumour is identification, the better the chance of successful removal and a good prognosis. As mentioned, these tumours are often locally invasive but slow to metastasise, however the level of malignancy and therefore prognosis is often related to the location of the neoplasm. Those arising over the tonsil (squamous carcinoma of the tonsil or tonsillar carcinoma) are very malignant, invading adjacent tissues and metastasising early. Squamous carcinomas of the tongue (especially in cats) can also behave in a very malignant fashion. Those at more rostral sites, e.g. on the incisor gingivae, are less likely to metastasize early although they may be locally aggressive. They should be staged according to the World Health Organisation (WHO) system.
Prevention
Squamous cell carcinomas can be prevented by protecting the skin from ultraviolet light. This may be achieved using sunblocks or by keeping the animals indoors or in the shade. This is rarely practicable.
| Squamous Cell Carcinoma Learning Resources | |
|---|---|
 Test your knowledge using flashcard type questions |
Cytology Q&A 14 |
References
Bond, Hendricks, Loeffler (2009) Veterinary Dermatology RVC Intergrated BVetMed Course, Royal Veterinary College
Freeman, KP (2007) Self-Assessment Colour Review of Veterinary Cytology - Dog, Cat, Horse and Cow Manson
Murphy, S (2006) Skin neoplasia in small animals 1. Principles of diagnosis and management In Practice 2006 28: 266-27
Murphy, S (2006) Skin neoplasia in small animals 2. Common feline tumours In Practice 2006 28: 320-32
Quinn, G (2003) Skin tumours in the horse: clinical presentation and management In Practice 2003 25: 476-48
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This article has been peer reviewed but is awaiting expert review. If you would like to help with this, please see more information about expert reviewing. |