Feline head and neck tumors (Proceedings)

Head and neck tumors are relatively common in aging cats. Understanding the differential diagnoses in this anatomic area is crucial as the diagnostic and therapeutic approaches may vary. This lecture will discuss feline oral tumors, sinonasal tumors, iris melanoma, Hodgkin's-like lymphoma, salivary gland tumors, tumors of the ear canal, and skin tumors.

ORAL TUMORS

Squamous cell carcinoma (SCC) is the most common tumor (over 70%) of the feline oral cavity, followed by fibrosarcomas (10-20%) and other tumors (osteosarcoma, epulides, lymphoma, melanoma, etc.). The median age of cats with oral SCC is 12 years, though cats below one year of age and as old as 21 years have been reported. Feline oral SCC may as a mass in the mouth noted by the owner, or for halitosis, weight loss, dysphagia or increased salivation. Some cases of SCC may demonstrate a true mass effect while others may simply be erosive and/or erythematous, mimicking periodontal disease. Loose teeth in an older cat should be evaluated for the possibility of underlying bone lysis, possibly due to SCC.

The diagnostic workup for a cat with suspected oral SCC should include a thorough history and physical examination (including oral exam: size, location, color, firmness, does it cross midline, etc.). A MDB including bloodwork, urinalysis +/- retroviral testing should be performed if not recently done. In addition, 3-view chest radiographs should be obtained, and FNA and cytology performed if any draining lymph node(s) is/are palpable, asymmetrical or enlarged. Lastly, a deep incisional biopsy should be performed for histopathologic examination and definitive diagnosis. Superficial biopsies may not be diagnostic as there is frequently hyperplasia and suppurative inflammation accompanying the underlying tumor. Obtaining tissue biopsies deep to where the loose tooth was is also crucial. High-detail dental radiographs (rostral or lateral mandible) or advanced sectional imaging such as CT scan or MRI (caudal mandible or any maxillary location) is required to better establish prognosis and plan therapeutic approach.

Feline oral SCC is an extremely invasive and malignant tumor and, to date, therapies that are consistently beneficial for feline oral SCC have not been found. The recurrence rate when treated with surgery alone is very high with a median survival time under a few months. The exception to this is cats with very small oral SCC involving the rostral or lateral mandible that may be treated with rostral or segmental mandibulectomy, respectively. Even these cases can have recurrence despite "clean" margins on histopathology. The use of radiation therapy as a sole treatment modality provided median survival times of < 3-6 months. Few reports exist on the sole use of chemotherapy for feline oral SCC and, despite the occasional clinical response, it is generally felt to be of modest benefit for the feline inoperable oral SCC patient. In general cats with inoperable oral SCC have a guarded to poor prognosis, with median survival times of 1-3 months and palliative and supportive therapy (multimodal analgesic therapy, feeding tube) is often most beneficial. A recent study in the UK demonstrated that the palliative use of a NSAID provided better survival times than no treatment at all.

Fibrosarcoma (FSA) is the second most common oral tumor in cats (10-20%) and generally occurs in older cats (median 11 years) though younger and older cats have been reported. There is no known gender predisposition or oral cavity site predilection, though most feline oral FSA arise in the gingiva. Little clinical information is available on cats with oral FSA. Most cats with oral FSA will present in ways similar to cats with SCC, except that cats with FSA nearly hallways have a mass effect at the tumor site. The workup for oral FSA is identical to that discussed above for oral SCC. Deep incisional biopsies are also recommended for definitive diagnosis.

Feline oral FSA are very locally invasive and require wide surgical excision. Minimal or conservative surgical excision generally results in local recurrence. Unfortunately, even aggressive surgical resection of these tumors with histopathologically confirmed "clean" margins may still result in recurrence in 20-30% of cases owing to their invasiveness. Though poorly reported, the use of radiation therapy may be beneficial in cases with incomplete surgical resection (microscopic disease), or when used palliatively (3-6 large doses) on inoperable disease. Similarly, despite chemotherapy is occasionally used in cats with large oral FSA in an attempt to downstage (cytoreduction) the tumor prio to surgical resection, or in cats with high-grade oral FSA (higher risk of metastatic dissemination).

SINONASAL TUMORS

Though sinonasal tumors are uncommon in cats, the most common cause of chronic nasal discharge in cats is neoplasia. They typically affect older cats, but can be seen in younger cats (especially lymphoma). Clinical signs include nasal discharge (epistaxis or mucopurulent), sneezing, stertor, upper respiratory dyspnea, lethargy, and decreased appetite. Facial deformity or ocular signs may be noted if the tumor invades the maxilla, frontal bones, or into the orbit. Nasal lymphoma, most commonly of B cell origin, is not associated with retroviral infection.

Lymphoma and carcinomas are the most common nasal tumors of cats (lymphoma slightly more frequent). Other tumor types include SCC, sarcomas (chondrosarcoma, osteosarcoma, and FSA), and less common tumors. Other differentials are chronic rhinitis, foreign body, nasopharyngeal stenosis, nasal polyps, and trauma.

Clinical staging includes physical examination, hematology, chemistry profile, urinalysis, retroviral testing, and T4 level for older cats. Advanced imaging (CT scan or MRI) is used to confirm a mass, determine of extent of local invasion, and for therapeutic planning. Skull radiographs are not as useful. Rhinoscopy may help visualize the lesion, but is rarely required in the diagnosis. Tissue biopsies are necessary for diagnosis, and can be obtained blindly through the nares using biopsy forceps (do not pass the medial canthus caudally!), or via forceful flushing of the nasal cavities with saline. Cytologic evaluation of the draining lymph nodes and chest radiographs are recommended even though metastatic disease in infrequent at diagnosis. Abdominal ultrasound may be indicated for evaluation of overall health prior to aggressive therapy.

Definitive radiation therapy is the treatment of choice for nasal tumors. This generally involves daily (M-F) treatments for 3-4 weeks. Early side effects of radiation are possible (oral mucositis, etc.) but are typically less severe than what is observed with dogs. Symptomatic management is recommend for these self-limiting (2-3 weeks) side effects. Late side effects include KCS, leukotrichia, cutaneous fibrosis, cataracts, chronic rhinitis, and changes in skin pigmentation. Severe late side effects requiring therapy occur in <5% of cats.

Combination chemotherapy (CHOP-like protocol) is indicated for cats with sinonasal lymphoma if systemic disease is present or when radiation therapy is not possible. For cats with localized disease treated with radiation therapy, the benefit of chemotherapy is less clear. Chemotherapy may be considered for cats with vascular/lymphatic embolization or metastasis of carcinomas or sarcomas. The choice of drug will depend on the histology. Symptomatic therapy is recommended for chronic rhinitis and includes antibiotic therapy for secondary infections or anti-inflammatory corticotherapy for nasal congestion.

Sinonasal tumors are locally invasive and local recurrence or progressive disease is usually the cause of death. The metastatic rate for most sinonasal tumors is low at diagnosis. Based on small studies of sinonasal carcinomas and sarcomas treated with radiation therapy, the average survival time is about 12-24 months and more than 20% of cats live 2 years. Sinonasal lymphoma is localized in most cats and a recent study of 19 cats treated with RT and chemotherapy showed local recurrence in 23.5% while 17.6% relapsed at distant sites. Cats with sinonasal lymphoma generally have a high response rate to radiation therapy and median survival time of around 2 years. Cats with cribriform plate invasion had markedly shorter survival times (76 days) compared to those without invasion (1296 days) in a recent study evaluating radiation therapy and chemotherapy.

OCULAR TUMORS

Feline "ocular tumors" may affect the globe, the orbit, or the surrounding tissues (adnexa), and can be primary or metastatic. This lecture will primarily focus on the most common feline primary intraocular tumor: iris melanoma.

For any can presenting with an ocular tumor, a complete ophthalmologic examination with Schirmer tear test, fluorescein staining, measurement of intraocular pressure, retropulsion of the eyes, examination of the anterior and posterior chambers, examination of adnexa, and fundic exam should be performed for both eyes. Additional ophthalmologic procedures may be indicated based on exam findings. Because most feline "ocular tumors" are malignant, cats should be staged with a minimum data base of physical examination, CBC, chemistry profile, urinalysis, retroviral test, and T4 level for older cats. Additional tests will depend on location of the tumor and diagnosis. Fine-needle aspiration and cytology of draining lymph nodes and thoracic radiographs are indicated for malignant tumors. Abdominal ultrasound may be indicated to search for a primary tumor if the ocular tumor is suspected to be a metastatic lesion, to look for systemic disease (ex: lymphoma), or to identify metastasis (ex: from melanoma). Abdominal ultrasound is always indicated in any cat for evaluation of overall health prior to aggressive/costly therapy. Advanced sectional imaging (CT or MRI) is indicated for invasive orbital tumors.

For intraocular tumors, ophthalmologic examination and ultrasound generally allow visualization of the mass. Depending on location, size, and appearance, monitoring for progression, fine needle aspiration ("vacuuming" the surface or the iris), intraocular resection, or enucleation may be recommended for diagnosis. The most common feline intraocular tumors are melanocytic in origin. Feline diffuse iris melanoma is the most common but atypical melanomas of the limbus, choroid, or multifocal melanomas may be seen. Benign iris nevi are also possible. Other intraocular tumors in cats include lymphoma, epithelial tumors (ciliary body), posttraumatic intraocular sarcomas, etc. The most common metastatic intraocular tumors are pulmonary and mammary adenocarcinoma.

Feline ocular melanoma is usually malignant, but slow to metastasize. Hence the debate over when it is best to enucleate. Because approximately 60% of ocular malignant melanomas will metastasize, the goal would be to enucleate prior to malignant transformation/dissemination, but this is currently impossible to predict. For older cats with concurrent diseases, lesions may be monitored, but in most cases, enucleation would be recommended at an early stage as described in table format below. Others have suggested that enucleation is justified based on: increases in area and volume of pigmented zones, any pigmented mass within the iridocorneal angle and sclerociliary cleft (as observed on gonioscopy), changes in pupillary shape and movement, or elevations in intraocular pressure.

Stages in the Development of Feline Diffuse Iris Melanoma

Transcorneal or transscleral Nd:YAG and diode lasers have been used for ablation of small intraocular tumors. This treatment is controversial for malignant tumors as recurrence and metastasis are possible. Iris melanoma is associated with a high metastatic rate, most typically to lungs, liver, and lymph nodes. However, because this tumor progresses slowly locally and since distant metastases may not be observed for 1 to 3 years, long survival times are possible. Therapies other than surgery (enucleation) have not been described for feline iris melanoma. In addition to treating the tumor, symptomatic and palliative therapies are indicated to control pain, decreased tear production, corneal ulceration, uveitis, or glaucoma depending on clinical findings at diagnosis.

HODGKIN'S-LIKE LYMPHOMA

A specific variant of lymphoma, Hodgkin's-like lymphoma has been described most commonly in cats, typically presenting in the form of mandibular lymphadenomegaly. It is called Hodgkin's-like because the neoplastic cells, including the classic binucleated Reed-Sternberg (RS) cells which are abnormal derivative of the B-cell lineage, and nodal architecture mimic what is observed with Hodgkin's lymphoma (aka Hodgkin's disease) in people. Another name that has been used to describe this variant of lymphoma in the veterinary literature, possibly erroneously, is that of T-cell rich B-cell lymphoma. Affected cats generally have no other clinical signs and are most typically presented for cervical masses, often unilaterally enlarged mandibular, and occasionally prescapular, lymph nodes. The average age at diagnosis is around 12 years of age and there is no known breed or sex predisposition.

The usual MDB is recommended at diagnosis (hematology, serum biochemistry, retroviral testing, urinalysis, T4 level for older cats, chest radiographs, abdominal U/S). Fine-needle aspiration and cytology of the enlarged lymph nodes, in conjunction with the clinical history, may help provide a presumptive diagnosis especially when classic RS cells are observed, but biopsy is essential for definitive diagnosis. Histopathology is generally not sufficient and histochemistry using various immunomarkers will help obtain a definitive diagnosis in the hands of an experienced veterinary pathologist.

Prospective clinical studies have not been performed to identify the best therapeutic approach for this subtype of feline lymphoma. The initial pathology studies describing the condition showed that some cats with a single enlarged lymph node may be best treated with surgery. Initially the often solitary enlarged lymph node is surgically removed and submitted for diagnostic purposes. Many cats will then enjoy many months (to more than a year) before a second lymph node (typically mandibular, external retropharyngeal, or prescapular) becomes clinically enlarged. This second lymph node may then also be removed, and so on. The added benefit of systemic chemotherapy or radiation therapy, similarly to what is standard of care with Hodgkin's lymphoma in people, remains to be determined in cats with Hodgkin's-like lymphoma. Anecdotally, some cats have lived more than 18 months with multimodality therapy, while others demonstrated aggressive, chemo- and radio-resistant disease.

SALIVARY GLAND TUMORS

Salivary gland tumors are uncommon in cats. The mandibular and parotid glands are most commonly affected, but involvement of the zygomatic, sublingual, and other minor salivary glands is also possible. The typical presenting sign is a nonpainful mass in the region of a salivary gland. Other clinical signs may include halitosis, weight loss/anorexia, dysphagia, Horner's syndrome, sneezing, dysphonia, and exophthalmia. Siamese cats may be overrepresented, there is a 2 to1 male:female ratio, and the median age at diagnosis is 12 years.

Fine needle aspiration and cytology may provide a presumptive diagnosis, but incisional biopsy and histopathology are required for definitive diagnosis. The bulk of feline salivary tumors are malignant. The most common tumor is simple adenocarcinoma, but SCC, anaplastic carcinoma, and other tumor types are also possible. Other differentials include sialadenitis, salivary gland infarction, sialocele, and normal salivary gland.

Cats with salivary gland tumors should be clinically staged with a minimum data base including a thorough physical examination, hematology, serum biochemistry profile, urinalysis, retroviral testing, and T4 level for older cats. Fine-needle aspiration of draining lymph nodes and chest radiographs are indicated for evaluation for metastasis. Salivary gland tumors can be quite invasive locally, and advanced sectional imaging (CT scan or MRI) is required for surgical or radiotherapeutic planning. Abdominal ultrasound may be indicated in evaluation of overall health prior to aggressive therapy.

Surgical removal is the treatment of choice for salivary gland tumors. Full course radiation therapy is indicated in the postoperative setting for incompletely excised tumors (microscopic disease) as salivary tumors appear to be fairly radiosensitive. For inoperable tumors, radiation therapy may still be an option. Systemic chemotherapy (ex: carboplatin, mitoxantrone, doxorubicin), though poorly documented in this setting, should be contemplated when detectable metastasis or vascular/lymphatic embolization (histopathology) is documented.

Feline salivary gland tumors are aggressive, both locally (risk of local recurrence) and with a high rate of metastasis (regional or distant). Nevertheless, these cats may enjoy long survival times with therapy, as demonstrated by the median survival time of 516 days in the largest published study.

TUMORS OF THE EAR CANAL

Tumors of the ear canal are uncommon in cats and most typically seen in older cats. Clinical signs include the presence of a mass, aural discharge or odor, and scratching of the ear. Horner's syndrome, vestibular signs, and facial paralysis are occasionally seen with more invasive tumors. Cats with tumors of the ear canal often have a history of chronic otitis unsuccessfully treated for long periods of time prior to diagnosis. Recurrent unilateral otitis in an older cat should increase the index of suspicion for an aural tumor as the possible underlying cause.

Tumors can often be visualized with otoscopic exam. Fine needle aspiration and cytology is useful to differentiate inflammatory from neoplastic lesions, but incisional biopsy and histopathology is often required for definitive diagnosis. In cats, more than 90% of ear canal tumors are malignant, the most common being ceruminous gland carcinoma, squamous cell carcinoma, and undifferentiated carcinoma. They are often quite locally invasive into the surrounding tissues, especially SCC. Detectable metastasis at diagnosis is uncommon. Benign ear canal masses include inflammatory polyp, ceruminous gland adenoma, ceruminous gland cysts (often numerous, bilateral, and dark), and papilloma.

Cats with malignant aural tumors are staged with a minimum data base including thorough physical examination, hematology, serum biochemistry profile, urinalysis, retroviral testing, and total T4 level for older cats. Regional lymph nodes (mandibular or external retropharyngeal) FNA/cytology and 3-view chest radiographs should be performed to evaluate for metastasis. Advanced sectional imaging (CT scan or MRI) of the ear lesion is important for therapeutic planning (surgery and/or radiation), and for prognostic information. Abdominal ultrasound may be indicated in any cat for evaluation of overall health prior to aggressive or radical therapy.

The best therapeutic approach of malignant tumors of the ear canal is total ear canal ablation and bulla osteotomy (TECABO). This surgery is generally well-tolerated though Horner's syndrome and facial paralysis are common temporary complications in a majority of patients. More conservative surgeries are unlikely to result in complete resection and recurrence is expected. For incompletely excised tumors or inoperable tumors, radiation therapy is effective. Chemotherapy should be considered when vascular/lymphatic embolization is observed on histopathology or when metastasis is docume+/nted. Undifferentiated carcinomas may occasionally metastasize early in the course of the diease. Palliative therapy, including analgesic therapy and antibiotics for secondary infection, is helpful pre- and post-operatively. For benign tumors, more conservative surgeries often will be curative.

Survival times can be encouraging, especially when early aggressive therapy is employed. A median survival time around 12 months has been reported for cats with surgically treated malignant tumors of the ear canal, though a majority of cats in that study died of problems unrelated to their tumors. Another study describing 16 cats treated for ceruminous gland adenocarcinoma with TECABO reported a 25% local recurrence rate, 75% 1-year survival, and 42 month overall median disease free interval. Factors predicting a shorter survival time included a diagnosis of undifferentiated carcinoma, secondary neurological signs, lymphatic/vascular embolization, and treatment with surgery other than TECABO. There is limited published information suggesting that tumors of the ear canal appear to be radioresponsive and that long term local control is possible when radiation therapy follows an incomplete excision. For large and invasive inoperable tumors, radiation therapy, along with multimodal analgesic therapy, may be palliative and improve the quality of life.

CUTANEOUS TUMORS

MAST CELL TUMORS (MCT)

Approximately 15-20% of feline cutaneous tumors are MCT, making it the second most common skin tumor in that species. About 50% of them occur on the head (haired skin, eyelids, pinnas, lips, etc.). They are usually seen in middle aged cats and Siamese cats appear to be overrepresented. Typically, MCT occur as solitary masses, though 15-20% will occur as multiple masses. The masses are often white to light pink and hairless. Larger lesions may be plaque-like, erythematous, swollen, or ulcerated.

MCT can usually be diagnosed cytologically, but may also occasionally be confused with eosinophilic granuloma. Biopsy and histopathology confirms diagnosis but, unlike canine MCT, histologic grade is not prognostic. Clinical staging includes physical examination, hematology (+/- buffy coat evaluation), serum biochemistry profile, urinalysis, retroviral testing, and T4 level for older cats. With solitary MCT, the draining lymph nodes should ideally be aspirated and the spleen evaluated via palpation. If these are both normal, further staging may not be necessary. For multiple or invasive masses however, if there is evidence of lymph node involvement or splenomegaly, or if the peripheral blood (blood smear or buffy coat) is positive for circulating mast cells, abdominal ultrasound, splenic aspiration and cytology, and bone marrow aspirate may also be in order.

The treatment of choice for feline MCT is surgical excision. Unlike dogs, wide margins are usually not necessary. The surgery performed should be according to the size of the tumor. For small superficial dermal MCT, strontium-90 radiation therapy (plesiotehrapy) can be used successfully and is well tolerated. External beam radiation therapy is to be considered for larger MCT.

Systemic chemotherapy, though poorly described in the literature for feline MCT, should be considered for unresectable or metastatic lesions, or when systemic or visceral involvement is noticed. There are no studies to demonstrate the drug of choice for this tumor in cats, but responses have been seen with prednisone, vinblastine, lomustine (CCNU), and chlorambucil. The newer targeted therapies (tyrosine kinase inhibitors) such as toceranib phosphate (Palladia) and masinitib mesylate (Masivet) are also therapeutic options to consider for aggressive feline MCT, and anecdotally tend to be fairly well tolerated in this species.

Symptomatic care for large, swollen, erythematous, painful, or metastatic lesions should include histamine blockade via H1 and H2 receptor antagonists. Cyproheptadine may be considered for H1 antagonism since it is also a serotonin antagonist and feline MCT tend to contain more serotonin than histamine. Famotidine is the most commonly used H2 receptor antagonist in cats.

Feline cutaneous MCTs are usually cured with surgery alone. If incompletely excised, options include revision surgery to remove the scar or radiation therapy, although many of these MCT will not recur. Rarely, cutaneous MCT may represent systemic dissemination of visceral MCT or be a more aggressive variant, demonstrating local invasiveness or metastasis. In a study of 32 cats with cutaneous MCT treated with surgery followed for a median of >3 years, only 5 recurred and most cats (28/32) were alive at the end of the study. Of 31% cats with complete excision 3 had local recurrence, compared to 2 local recurrences in the 63% that had incomplete excision of their MCT. Another study of 30 cats with MCT reported local regrowth in 10 cats, metastasis to the draining lymph node in 1, and nodular cutaneous dissemination with systemic signs in 2 cats. Finally, of 15 cats surgically treated for pleomorphic cutaneous MCT in a study, 2 recurred, including one with a high mitotic index that developed multiple dermal MCTs within 5 months.

A study of cats with multiple (5 or +) MCT, recurrent MCT, or primary splenic MCT disease and demonstrate a more guarded prognosis. Many of these still lived for 12 months or more, however, and treatment is nevertheless indicated. A study on 35 cats with single or multiple small superficial cutaneous MCTs treated with strontium-90 radiation therapy demonstrated that the tumors were controlled in 98% of them at a median of 783 days. There is no information to describe response to external beam radiation therapy, but this treatment would be an option for cats with more extensive tumors.

Basal Cell Tumors (basal cell epithelioma, basal cell carcinoma, basaloid tumor)

Most common feline skin tumor, basal cell tumors are typically diagnosed in middle aged to older cats and commonly found on the head, neck, or shoulder area. They are typically solitary, well-circumscribed, firm, hairless, dome-shaped, usually moveable, and elevated masses. They can be pigmented (most common pigmented tumor in cats), and melanocytic tumors are an important differential, and can ulcerate.

Surgical resection is generally curative with the typical bening basal cell tumor. If malignant, draining local lymph node aspiration and cytology 3-view chest radiographs are indicated, and second surgery (scar + margins) or radiation therapy should be considered if incompletely excised. Chemotherapy may also be contemplated with malignant tumors if vascular or lymphatic embolization is noticed on histopathology.

VASCULAR TUMORS (hemangioma and hemangiosarcoma)

Most commonly seen in older cats, they can present as superficial cutaneous (dermal) or subcutaneous masses that appear red or purple. Superficial (dermal) hemangiosarcoma (HSA) may be induced by chronic UV exposure in cats and may be seen on the pinna, preaural area, eyelids, and conjunctivae of lightly pigmented cats. Subcutaneous HSA is most common in the inguinal or caudal abdomen area and on the head.

Diagnosis of HSA is obtained with incisional biopsy and histopathology. For the occasional anaplastic/poorly differentiated tumor, immunohistochemical staining for factor VIII-related antigen (vWF) can be used to confirm the diagnosis. Solar (UV) induced changes such as dermal elastosis and actinic keratosis may be observed in the skin surrounding dermal HSA or as pre-neoplastic lesions. Because cutaneous HSA can metastasize to inner organs or could alternately represent metastasis from visceral HSA, further clinical staging tests are indicated. Cats with HSA should be staged with a thorough physical examination, hematology, biochemistry profile, urinalysis, retroviral testing, and T4 level (older cats). Cytologic evaluation of local lymph node aspirates is to be considered. In addition, chest radiographs (3 views) and abdominal ultrasound are recommended.

Surgery is the main treatment for cutaneous HSA. Subcutaneous lesions usually require wider surgical excision with lateral margins and an underlying tissue plane. Surgery alone may be curative for dermal and subcutaneous HSA, but local recurrence and metastasis are possible. Small superficial UV-induced HSA may also be treated with strontium-90 therapy (plesiotherapy) or topical application of imiquimod (anecdotal). Based on information in dogs, doxorubicin-based chemotherapy should be considered with subcutaneous lesions (especially if invasive into the muscle), those with vascular/lymphatic embolization, or when detectable metastasis is present. Radiation therapy may be helpful for controlling incompletely excised tumors (microscopic disease) or to palliate inoperable invasive lesions.

There is still limited information describing the prognosis of HSA in cats. Most hemangiomas and superficial dermal HSA are cured with complete surgical excision, but other (de novo) lesions may develop and avoiding chronic UV exposure is important. Obtaining clean margins bears prognostic importance for survival of cats with cutaneous or subcutaneous HSA treated with surgery alone or followed with adjuvant doxorubicin chemotherapy. In a study on 10 cats treated surgically for subcutaneous HSA, survival times varied from 13 weeks to more than 2 years, with more than 50% developing local recurrence. Another study of 18 cats with cutaneous HSA reported a median survival time of 912 days, and cats treated with surgery lived significantly longer than those not surgically treated. An older study described local recurrence (1 month to 2 years following surgery) but no metastasis in 7 cats with cutaneous HSA, which differs from another report discussing 8 cats with cutaneous HSA that all developed metastasis.