open sore on toe of paw try asking this in the pet section. Get your cat to the vet for treatment.
Squamous cell carcinoma (SCC) is the second most common form of skin cancer, with over 250,000 new cases per year estimated in the United States. It arises in the squamous cells that compose most of the upper layer of the skin.
Most SCCs are not serious. When identified early and treated promptly, the future is bright. However, if overlooked, they are harder to treat and can cause disfigurement. While 96 to 97 percent of SCCs are localized, the small percentage of remaining cases can spread to distant organs and become life-threatening.
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Squamous Cell Carcinoma -Skin
Squamous cell carcinoma (SCC) is a common tumor involving the skin and accounts for approximately 15% of cutaneous tumors in the cat and 5% of those in the dog. SCCs are usually found in unpigmented or lightly pigmented skin. In many instances there is a recognized solar exposure relationship and these tumors are often referred to as "actinic" SCC. The most common cutaneous locations for SCC in the cat are the sparsely haired areas of the nasal planum, eyelids, and pinnae Multiple facial lesions are present in nearly 30% of affected cats. Squamous cell carcinoma usually afflicts older animals (mean age of 12 years in the cat, 8 years in the dog). Siamese cats are under-represented, as would be expected because of pigmented skin color.
SCC may present as either a proliferative or erosive lesion. Proliferative lesions may vary from a red firm plaque to a
cauliflowerlike lesion that often ulcerates. The erosive lesion, which is most common in the cat, initially starts as a shallow crustinglesion that may develop into a deep ulcer. Histologically, the initial crusting lesions often represent carcinoma in situ or preinvasive carcinoma..
Generally, SCCs involving the facial skin of cats are locally invasive but late to metastasize. The degree of local invasion can be quite severe and response to therapy is much more successful for Tis to T1 lesions than for those with significant invasion. The behavior of subungual (nail bed)
Many therapeutic modalities have been applied to SCC involving the facial skin in cats. Surgery or Cryosurgery are most commonly used and remain the mainstay for treating these lesions, although numerous reports now exist detailing the use of radiotherapy and photodynamic therapy. Outcomes are generally good for most modalities if the tumors are treated early (i.e., Tis to T1) in their course. In general, lesions of the pinna are more manageable than those of the nasal planum because the location allows a more aggressive surgical or cryosurgical dose. Surgical excision of lesions of the pinnae result in long-term control (> 1.5 years) in the majority of cases. In a report of 102 cats with 163 lesions, aggressive cryotherapy was nearly 100% effective for managing pinnae and eyelid tumors; however, only 70% of nasal planum, tumors responded. 0rthovoltage radiotheropy using 40 Gray total dosage in 10 fractions was applied in 90 cats with nasal planurn SCC. Turnor stage was found to be highly prognostic, as Tis and Ti lesions enjoyed 5-year progression-free survivals of 56%, while tumors of higher stages responded poorly. Survival in this report could also be predicted by determining the proliferation fraction of the tumor using an immunohistochernical stain for PCNA (proliferating cell nuclear antigen). Similarly, the use of strontium plesiotherapy, a form of superficial radiotherapy, has provided long-term control (1 and 3-year control rates of 89 and 82%, respectively) in 25 cats with early superficial lesions. Plesiotherapy is limited to very early, shallow lesions because the radiation dose drops off significantly below depths of 2 mm. Photodynamic therapy has also been studied extensively for the treatment of superficial SCC in both the dog and cat. Once again, if applied to early lesions, results are generally positive. Complete response rates of approximately 75% are reported for Tis to T2 staged tumors and drop off quickly to 30% for tumors of higher stages. The bottom line with respect to treating local SCC lesions is to treat small lesions aggressively. Presently, combinations of surgery and radiation therapy for infiltrative nasal planum SCC are being evaluated and show early promise.
Chemotherapy for cutaneous SCC has shown little consistent efficacy in the veterinary literature. Agents that have been
investigated on a limited basis for SCC in the dog and cat include mitoxantrone, actinomycin D, doxorubicin/ cyclophosphamide combinations, bleomycin, and cisplatin (not used in cats). Response rates are generally low and short-lived in duration. Chemotherapy in an adjuvant setting for microscopic disease following surgery or in conjunction with radiotherapy should be investigated for high-grade lesions. Intralesional sustained release cisplatin and 5-FU have also been investigated in dogs, along with local hyperthermia and alone in cats with superficial SCC. Long-term results are lacking; however, nearly half of the cats and dogs with actinic-related SCC have achieved a complete response.
The vitamin A-related synthetic retinoids have also been evaluated in dogs and cats with solar-induced cutaneous SCC. Only preneoplastic lesions were responsive to etretinate and early superficial lesions to a combination of isotretinoin and local hyperthermia in the dog. No significant response was noted in 10 cats treated with isotretinoin.
The nonsteroidal anti -inflammatory drug piroxicam, also known for its immunomodulating effects, has also been evaluated for efficacy in dogs with nonresectable SCC. Partial responses were noted in half of the 10 patients treated, with a resulting median survival of 150 days.
A relatively new variation of SCC reported in cats is best referred to as Multicentric SCC in situ (MSCCIS, also called Bowen's disease, or Bowenoid carcinoma in situ). Unlike actinic or solar-induced SCC in situ, MSCCIS is found in haired, pigmented areas of the skin and is unrelated to sunlight exposure. It has not been associated with either, FeLV or FIV viral infections. Multiple lesions are usually present in older cats, and lesions are confined to the epithelium, with no breachment of the basement membrane. The lesions are generally crusty, easily epilated, painful, and hemorrhagic when manipulated. They are felt to be preneoplastic, because three cats had true SCC adjacent to sites of MSCCIS. When excision is possible, recurrence has not been reported; however, similar lesions often develop at other sites. They are unresponsive to antibiotics and corticosteroids, and variably responsive to strontium plesiotherapy. |
