- Email: [email protected]
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keratinous cysts, and papillomas. Multiple cutaneous horns have been reported on multiple footpads of FeLV-positive cats. Horns on the footpads of FeLV-negative cats occur as well, but are restricted to subungual sites. Although cutaneous horns are themselves benign, excisional biopsy is recommended to determine their underlying cause. BIBLIOGRAPHY Curiel-Lewandrowski C, Demierre M-F: Advances in specific immunotherapy of malignant melanoma, J Am Acad Dermatol 43:167-185, 2000. Fleischmann WR Jr, Koren S: Systemic effects of orally administered interferons and IL-2, J Interferon Cytokine Res 19:829-839, 1999. Goldshmidt MH, Shofer FS: Skin tumors of the dog and cat. Oxford, 1998, Butterworth-Heinemann. Gross TL, Ihrke P, Walder E: Veterinary dermatopathology. A macroscopic and microscopic evaluation of canine and feline skin disease, St Louis, 1992, Mosby. Gupta AK, Browne M, Bluhm R: Imiquimod: a review, J Cut Med Surg 6:554-560, 2002. Kirkham N: Tumors and cysts of the epidermis. In Elder E, Elenitsas R, Jaworsky C, et al: Lever’s histopathology of the skin, ed 8, Philadelphia, 1997, Lippincott-Raven, pp 685-746. Le Clerc SM, Clark EG, Haines DH: Papillomavirus infections in association with feline cutaneous squamous cell carcinoma in situ, 13th Proceedings of the AAVD/ACVD, 1997, pp 125-126. Le Net JL, Orth G, Sundberg JP, et al: Multiple pigmented cutaneous papules associated with a novel canine papillomavirus in an immunosuppressed dog, Vet Pathol 34:8-14, 1997. Nagata M, Nanko H, Moriyama A, et al: Pigmented plaques associated with papillomavirus infection in dogs: is this epidermodysplasia verruciformis? Vet Pathol 6:179-186, 1995. Ogilvie GK, Moore AS: Managing the veterinary cancer patient, Trenton, NJ, 1995, Veterinary Learning Systems. Penneys N: Diseases caused by viruses. In Elder E, Elenitsas R, Jaworsky C, et al (eds): Lever’s histopathology of the skin, ed 8. Philadelphia, 1997, Lippincott-Raven, pp 569-589. Scott DW, Miller WH, Griffin CE: Muller and Kirk’s small animal dermatology, ed 6, Philadelphia, 2000, WB Saunders. Stokking LB, Campbell KL. Bowen’s disease (multicentric squamous cell carcinoma in situ), Consult Fel Intern Med 4:208-213, 2001. Sundberg JP, Smith EK, Herron AJ, et al: Involvement of canine oral papillomavirus in generalized oral and cutaneous verrucosis in a Chinese Shar Pei dog, Vet Pathol 31:183-187, 1994. Tanabe C, Kano R, Nagata M, et al: Molecular characteristics of cutaneous papillomavirus from the canine pigmented epidermal nevus, J Vet Med Sci 62:1189-1192, 2000. Teifke JP, Lohr CV, Shirasawa H: Detection of canine oral papillomavirus-DNA in canine oral squamous cell carcinomas and p53 overexpressing skin papillomas of the dog using the polymerase chain reaction and nonradioactive in situ hybridization, Vet Microbiol 60:119-130, 1998. Tompkins W: Immunomodulation and therapeutic effects of the oral use of interferon α: mechanism of action, J Interferon Cytokine Res 19:817-828, 1999.
52. TUMORS OF ADNEXAL ORIGIN Thomas O. Manning, DVM, MS, DACVD Brett C. Wood, DVM 1. Skin neoplasms (dog and cat) are accountable for the following approximate percentage of all neoplasms: Dog (skin neoplasms) = 30% of total neoplasms Cat (skin neoplasms) = 20% of total neoplasms The incidence of skin neoplasia is approximately six times greater in the dog than in the cat.
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2. How are these skin neoplasms categorized (tissue of origin) in the dog and cat, and what is the general prevalence of each type? Dog: 55% mesenchymal, 40% epithelial, 5% melanocytic Cat: 50% epithelial, 48% mesenchymal, 25% melanocytic 3. What are major characteristics of malignant neoplasia involving the skin or subcutaneous tissue? • Sudden onset • Infiltrative growth • Rapid growth • Recurrence • Ulceration, irritation • Metastasis The most important criterion of malignancy is metastasis. 4. What is the key to appropriate management and accurate prognosis of cutaneous neoplasms? Specific diagnosis, which can only be achieved with surgical cutaneous biopsy sample, histologic evaluation, and proper clinical staging when appropriate. 5. Is exfoliative cytology (aspiration and/or impression smears) accurate in all cases of dermal neoplasia? • Exfoliative cytology techniques (aspiration and impression) are easy, rapid, and may provide valuable information concerning cell type and differentiation in some instances of dermal neoplasia (mast cell tumor, melanocytic tumors). • However, exfoliative cytologic examination is inferior to and cannot substitute for histopathologic diagnosis for most cases. “A lump is a lump, until examined histologically.” 6. List some of the reasons for the growing importance of special stains (cytokeratins) and immunohistochemical stains. • These stains may help separate the more anaplastic tumors into specific categories. • Predict future malignancy • By more accurate diagnosis, treatment can be more specific 7. What is an intracutaneous cornifying epithelioma (ICE) (keratoacanthoma, infundibular keratinizing acanthoma)? • An uncommon, benign skin tumor seen in dogs • Unsubstantiated reports in cats • Occurs in dogs younger than 5 years of age • Clinically may have a “rabbit’s foot” appearance 8. What forms does ICE occur in and in what breeds is it seen? Solitary Collie Lhasa Apso Yorkshire Terrier
Generalized Norwegian Elkhound Keeshond German Shepherd Dog Old English Sheepdog
9. What are the treatment modalities available for both types of ICE? Solitary • Surgical excision using conventional methods • Radiation therapy or laser therapy • Cryotherapy is also useful for single, smaller lesions
404
Tumors of Adnexal Origin Multiple • Cryotherapy for a small number of multiple lesions • ICE therapy with vitamin A–related synthetic retinoids (isotretinoin, etretinate, or acretinoin) has been used with some success. • CO2 laser ablation
10. Surveys of hair follicle neoplasia in dogs and cats indicate that these neoplasms account for % of skin tumors? Dogs = 5% Cats = 1% 11. What are neoplasms arising from the region of the hair follicle in the dog and cat? • Tricholemmoma • Trichoepithelioma • Trichoblastoma • Pilomatrixoma 12. With the reclassification of so-called basal cell tumors (see previous chapters), it seems that the majority of previous reports of these neoplasms would currently be classified as what type of neoplasia? Trichoblastoma; therefore, neoplasms of the hair follicle are much more common than recognized in earlier veterinary literature. 13. What are the characteristics of trichoblastomas? • Common • Usually benign • Derived from primitive hair germ cells • Poodle, Cocker Spaniel breeds are predisposed • Solitary, dome shaped firm, 1-2 cm diameter • Occur most commonly on the head, neck, or base of the ear 14. What are the characteristics of trichoepitheliomas? • Usually solitary (Figure 52-1) • Rarely invasive or metastatic (Figure 52-2) • Dorsal lumbar, lateral thoracic, and extremities are common sites. • Basset Hounds, Cocker and English Springer Spaniels, German Shepherd Dogs, Golden Retrievers, Miniature Schnauzers, and Standard Poodles are predisposed.
Figure 52-1 Cross-section of canine trichoepithelioma.
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Figure 52-2 Photomicrograph of canine trichoepithelioma (H&E ×100). 15. What are the characteristics of pilomatrixomas? • Uncommon in dogs, rare in cats • Predilection for neck, shoulders, lateral thorax, and back 16. Breeds predisposed to pilomatrixoma are: • Kerry Blue Terrier • Poodle • Old English Sheepdog 17. On cutting into a cutaneous neoplasm, it is found to be very firm, and the central core shows areas of calcification. This is suggestive of which of the following tumors? (a) Trichoepithelioma (b) Pilomatrixoma (c) ICE (d) Epidermal inclusion cyst (e) Corynebacterium spp. infection Correct answer is (b) Pilomatrixoma 18. Incidence of sebaceous gland tumors, growths arising from sebocytes, is and in cats. • Common in the dog, representing from 6-21% of all canine skin tumors • Uncommon in the cat
in dogs
19. What are the breeds most commonly affected with sebaceous gland tumors? • Beagle • Dachshund • Cocker Spaniel • Miniature Schnauzer • Poodle 20. What is the percent occurrence of the different sebaceous gland tumors and their breed associations (see previous question) and site predilections (if any)? • Nodular sebaceous hyperplasia: 53% • Sebaceous epithelioma: 37%, Shih Tzu, Lhasa Apso, Malamute, Siberian Husky, Irish Setter
406
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Figure 52-3 Sebaceous gland hyperplasia involving the medial canthus of an English Setter.
Figure 52-4 Nodule consisting of sebaceous gland hyperplasia on the paw of a Cocker Spaniel. • Sebaceous adenoma: 8%, Poodle, eyelid and limbs (Figure 52-3) • Sebaceous carcinoma: 2%, Cocker Spaniel, head and limbs (Figure 52-4) 21. What happens to nodular sebaceous hyperplasia (is there a progression to neoplasia)? Eighty-one percent of sebaceous epitheliomas and 54% of sebaceous adenomas had areas of sebaceous hyperplasia peripheral to and often mixing into neoplastic areas. These findings suggest that sebaceous hyperplasia may be a precursor to sebaceous epitheliomas and adenomas. 22. Which of the following statements is most correct regarding sebaceous gland tumors in the dog? (a) All sebaceous glands are malignant (b) Show no age or breed predilection; majority of tumors are malignant (c) Mostly in older, giant breed dogs; majority of tumors are benign (d) Mostly in older small breed dogs; majority of tumors are benign Correct answer is (d)
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23. Which of the following statements regarding perianal (hepatoid) gland tumors is correct? (a) Malignant, most commonly arise in the perianal areas of older male dogs (b) Benign, most commonly arise in the perianal areas of older male dogs (c) Malignant, most commonly arise in the perianal areas of older female dogs (d) Benign, most commonly arise in the perianal areas of older female dogs Correct answer is (b) 24. Perianal (hepatoid) glandular tissue may be found on the dog around the: (a) Anus (d) Skin of the lumbar and sacral areas (b) Prepuce (e) All of the above (c) Dorsal area of the tail Correct answer is (e) 25. What are therapeutic choices when treating perianal (hepatoid) gland adenomas? (a) Castration is probably the single best initial choice. Tumors may regress spontaneously over the 1- to 2-month postoperative period or reduce greatly in size, making surgical removal easier. (b) Cryosurgery is used primarily for tumors that are less than 1-2 cm in diameter. (c) Systemic administration of long-acting estrogenic compounds has been used before surgical debulking, but chronic use runs a substantial risk of bone marrow suppression. (d) External beam radiation therapy has been reported in the treatment of benign and malignant perianal/anal tumors but is used as more of a last resort due to increased cost and possible morbidity associated with procedure. 26. Is there a gender predilection for perianal gland adenomas and adenocarcinomas in the dog? Perianal gland adenomas are nine times more common in male than in female dogs (Figure 52-5). Perianal gland adenocarcinomas occur with equal frequency in both sexes (Figure 52-6). 27. How do circumanal gland (apocrine) carcinomas differ in their disease progression compared to perianal gland adenomas? • Grow more rapidly • Grow larger • Ulcerate 28. Are there prognostic indicators for dogs with perianal tumors? Yes, Tumor Size • Dogs with lesions greater than 5 cm. have an 11-fold higher risk of dying of tumor-related causes; in particular, metastasis to sacral and sublumbar lymph nodes. • Metastasis occurs in approximately 30% of cases. 29. How common are apocrine gland neoplasms of the dog and cat? • Primary apocrine gland neoplasia is rare in dogs (approximately 2% of all skin tumors) • More common in cats than sebaceous gland tumors. • Adenocarcinomas are more common than adenomas (50-90% malignant). • There are two modified apocrine gland tumors, ceruminous gland tumors of the ear and apocrine gland tumors of the anal sac, that are more commonly seen in the veterinary patient. 30. What clinical features are consistently helpful in differentiating histologically benign from histologically malignant tumors? • There are no clinical features that help.
408
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Figure 52-5 Perianal adenoma in an intact male dog.
Figure 52-6 Perianal adenocarcinoma in an intact female dog.
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• Therefore, another reason for excisional biopsies with wide surgical margins. • Unfortunately a common area on which adnexal tumors grow are the limbs; therefore making complete surgical removal a more difficult, sometimes impossible procedure. Tissue flap/plastic procedures, radiation, or limb amputation would then be considered. • However, incisional biopsy before aggressive surgery or adjunctive procedures is always recommended. 31. What are some special stains that can sometimes differentiate apocrine (epitrichial) adenomas from adenocarcinomas? • Apocrine sweat gland (epitrichial) tumors are positive for cytokeratins. • Carcinomas, not adenomas, are positive for carcinoembryonic antigen (secretory cell) and vimentin (myoepithelial cell). 32. What are the most common neoplasms of the ear canal? • Inflammatory polyps • Papillomas • Basal cell tumors • Ceruminous gland adenomas (Figure 52-7)
Figure 52-7 Ceruminous gland adenoma (1 cm diameter) and ceruminous cysts (1 mm diameter) in the external ear canal of a cat.
• Common malignant tumors found in the ear canal include ceruminous gland adenocarcinoma, squamous cell carcinoma, and carcinoma of undetermined origin. 33. What are the most common ear pinnal neoplasms? DOG Sebaceous gland tumors Histiocytoma Mast cell tumor Melanocytic neoplasms
CAT Squamous cell carcinoma Basal cell tumor Hemangiosarcoma
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34. Are ceruminal gland tumors usually benign? • Dog: ceruminal gland tumors are typically benign • Cat: ceruminal gland tumors are malignant in 50% of cases 35. What are common clinical observations in animals with ear canal tumors? • Older animals • Unilateral involvement only • Head scratching/head-shaking behavior • Frequent secondary bacterial/yeast infections with no history of problems • Aural discharge and/or intermittent hemorrhage from affected ear • Occasionally cause bulging, ulceration/draining mass below ear in the parotid region of the skull • Neurologic signs (peripheral vestibular disease, facial nerve paresis, Horner’s syndrome) are noted in approximately 10% of dogs and approximately 25% of cats with ear canal tumors. 36. What does proper clinical staging of an ear canal–based tumor include? • Minimum database (complete blood cell count, serum biochemistry, urinalysis) • Thoracic radiography • Fine needle aspirate or excisional biopsy of local lymph nodes • Radiologic study of the skull: computed tomography of the ear canal and tympanic bullae is recommended due to improved ability to evaluate soft tissue and bony changes and evidence of local extension. Skull radiographs may be used to evaluate primarily for evidence of bony changes and superimposition of anatomic structures may occur. • Incisional biopsy may be recommended in cases of suspected neoplasia if owners are considering adjunctive therapies instead of primary surgical excision. 37. What is the only effective therapy for an ear canal–based ceruminal tumor? • Complete surgical excision, usually by lateral ear resection or total ear canal ablation (TECA) • The best results are achieved with TECA and lateral bulla osteotomy. • The approximate recurrence rate for ceruminous gland tumors after lateral ear resection is 70%. 38. What is the most common signalment for anal sac gland tumors (apocrine)? Older female dogs, often associated with hypercalcemia of malignancy (PTHrP). 39. In a female dog, which of the following tumors is most likely to show metastasis to regional lymph nodes? (a) Anal gland tumor (b) Squamous cell carcinoma (c) Papilloma (d) Intracutaneous cornifying epithelioma Correct answer is (a) 40. What are common clinical signs noted in animals afflicted with anal sac adenocarcinoma? • Palpable rectal mass noted in the region of the anal sac • Perineal swelling • Tenesmus • Constipation/obstipation • Change in the shape of stool • Polyuria/polydipsia (associated with hypercalcemia)
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41. What does the recommended clinical staging of an anal sac tumor include? • Minimum database (complete blood cell count, serum chemistry, urinalysis) • Thoracic radiography (low yield procedure) • Abdominal imaging to evaluate regional lymph nodes • In general, ultrasonography of the abdomen is considered superior to caudal abdominal radiography for examination of regional lymphadenomegaly. • Rectal examination • Exfoliative cytology of this region is usually unrewarding in differentiation between benign and malignant processes in this region. 42. What is the general prognosis for animals with anal sac apocrine gland adenocarcinoma? • In general, the prognosis is poor; mean survival times for females is approximately 12 months with local recurrence occurring in approximately 50% of operated cases. • Metastasis and hypercalcemia are both considered poor prognostic indicators (approximate 6-month survival vs 12-month survival times). 43. What are adjunctive therapies for anal sac adenocarcinoma? External beam radiation has been offered as a monotherapy or as adjunctive therapy in cases of incomplete resection with variable results. The efficacy for this tumor is unknown, but in most cases chemotherapeutic agents have not been useful as an adjunctive therapy. One study revealed partial remission in approximately 30% of dogs using the platinum compounds. 44. Eccrine (atrichial) sweat gland tumors of the dog and cat: • May be benign or malignant in the dog • Almost always malignant in the cat • Are restricted to locations on the paw pads or digits BIBLIOGRAPHY Bevier DE, Goldschmidt MH: Skin tumors in the dog. I. Epithelial tumors and tumor like lesions, Compend Cont Ed Small Anim Vet Med 3(5):389-399, 1981. Bevier DE, Goldschmidt MH: Skin tumors in the dog. II. Tumors of the soft (mesenchymal) tissues, Compend Cont Ed Small Anim Vet Med 3(6):506-520, 1981. Cowell RL, Tyler RD, Meinkoth JH: Diagnostic cytology and hematology of the dog and cat. ed 2, St. Louis, 1999, Mosby. Fitzpatrick JE, Aeling JL (eds): Dermatology secrets in color, ed 2. Philadelphia, 2001, Hanley & Belfus. Goldschmidt MH, Bevier DE: Skin tumors in the dog. Part III: lymphohistiocytic and melanocytic tumors, Compend Cont Ed Small Anim Vet Med 3:588-597, 1981. Goldschmidt MH, Dunstan RW, Stannard AA, von Tscharner C, et al: Histological classification of epithelial and melanocytic tumors of the skin of domestic animals, AFIP, Am Reg Pathol WHO (series 2), vol 3, Washington, DC, 1998. Goldschmidt MH, Shofer FA: Skin tumors of the dog and cat. Oxford, 1992, Pergamon. Gross TL, Ihrke PJ, Walder EJ: Veterinary dermatopathology: a macroscopic and microscopic evaluation of canine and feline skin disease, St Louis, 1992, Mosby. Scott DW, Miller WH, Griffin CE: Muller & Kirk’s small animal dermatology, ed 6. Philadelphia, 2000, WB Saunders.
Tumors of Adnexal Origin
keratinous cysts, and papillomas. Multiple cutaneous horns have been reported on multiple footpads of FeLV-positive cats. Horns on the footpads of FeLV-negative cats occur as well, but are restricted to subungual sites. Although cutaneous horns are themselves benign, excisional biopsy is recommended to determine their underlying cause. BIBLIOGRAPHY Curiel-Lewandrowski C, Demierre M-F: Advances in specific immunotherapy of malignant melanoma, J Am Acad Dermatol 43:167-185, 2000. Fleischmann WR Jr, Koren S: Systemic effects of orally administered interferons and IL-2, J Interferon Cytokine Res 19:829-839, 1999. Goldshmidt MH, Shofer FS: Skin tumors of the dog and cat. Oxford, 1998, Butterworth-Heinemann. Gross TL, Ihrke P, Walder E: Veterinary dermatopathology. A macroscopic and microscopic evaluation of canine and feline skin disease, St Louis, 1992, Mosby. Gupta AK, Browne M, Bluhm R: Imiquimod: a review, J Cut Med Surg 6:554-560, 2002. Kirkham N: Tumors and cysts of the epidermis. In Elder E, Elenitsas R, Jaworsky C, et al: Lever’s histopathology of the skin, ed 8, Philadelphia, 1997, Lippincott-Raven, pp 685-746. Le Clerc SM, Clark EG, Haines DH: Papillomavirus infections in association with feline cutaneous squamous cell carcinoma in situ, 13th Proceedings of the AAVD/ACVD, 1997, pp 125-126. Le Net JL, Orth G, Sundberg JP, et al: Multiple pigmented cutaneous papules associated with a novel canine papillomavirus in an immunosuppressed dog, Vet Pathol 34:8-14, 1997. Nagata M, Nanko H, Moriyama A, et al: Pigmented plaques associated with papillomavirus infection in dogs: is this epidermodysplasia verruciformis? Vet Pathol 6:179-186, 1995. Ogilvie GK, Moore AS: Managing the veterinary cancer patient, Trenton, NJ, 1995, Veterinary Learning Systems. Penneys N: Diseases caused by viruses. In Elder E, Elenitsas R, Jaworsky C, et al (eds): Lever’s histopathology of the skin, ed 8. Philadelphia, 1997, Lippincott-Raven, pp 569-589. Scott DW, Miller WH, Griffin CE: Muller and Kirk’s small animal dermatology, ed 6, Philadelphia, 2000, WB Saunders. Stokking LB, Campbell KL. Bowen’s disease (multicentric squamous cell carcinoma in situ), Consult Fel Intern Med 4:208-213, 2001. Sundberg JP, Smith EK, Herron AJ, et al: Involvement of canine oral papillomavirus in generalized oral and cutaneous verrucosis in a Chinese Shar Pei dog, Vet Pathol 31:183-187, 1994. Tanabe C, Kano R, Nagata M, et al: Molecular characteristics of cutaneous papillomavirus from the canine pigmented epidermal nevus, J Vet Med Sci 62:1189-1192, 2000. Teifke JP, Lohr CV, Shirasawa H: Detection of canine oral papillomavirus-DNA in canine oral squamous cell carcinomas and p53 overexpressing skin papillomas of the dog using the polymerase chain reaction and nonradioactive in situ hybridization, Vet Microbiol 60:119-130, 1998. Tompkins W: Immunomodulation and therapeutic effects of the oral use of interferon α: mechanism of action, J Interferon Cytokine Res 19:817-828, 1999.
52. TUMORS OF ADNEXAL ORIGIN Thomas O. Manning, DVM, MS, DACVD Brett C. Wood, DVM 1. Skin neoplasms (dog and cat) are accountable for the following approximate percentage of all neoplasms: Dog (skin neoplasms) = 30% of total neoplasms Cat (skin neoplasms) = 20% of total neoplasms The incidence of skin neoplasia is approximately six times greater in the dog than in the cat.
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2. How are these skin neoplasms categorized (tissue of origin) in the dog and cat, and what is the general prevalence of each type? Dog: 55% mesenchymal, 40% epithelial, 5% melanocytic Cat: 50% epithelial, 48% mesenchymal, 25% melanocytic 3. What are major characteristics of malignant neoplasia involving the skin or subcutaneous tissue? • Sudden onset • Infiltrative growth • Rapid growth • Recurrence • Ulceration, irritation • Metastasis The most important criterion of malignancy is metastasis. 4. What is the key to appropriate management and accurate prognosis of cutaneous neoplasms? Specific diagnosis, which can only be achieved with surgical cutaneous biopsy sample, histologic evaluation, and proper clinical staging when appropriate. 5. Is exfoliative cytology (aspiration and/or impression smears) accurate in all cases of dermal neoplasia? • Exfoliative cytology techniques (aspiration and impression) are easy, rapid, and may provide valuable information concerning cell type and differentiation in some instances of dermal neoplasia (mast cell tumor, melanocytic tumors). • However, exfoliative cytologic examination is inferior to and cannot substitute for histopathologic diagnosis for most cases. “A lump is a lump, until examined histologically.” 6. List some of the reasons for the growing importance of special stains (cytokeratins) and immunohistochemical stains. • These stains may help separate the more anaplastic tumors into specific categories. • Predict future malignancy • By more accurate diagnosis, treatment can be more specific 7. What is an intracutaneous cornifying epithelioma (ICE) (keratoacanthoma, infundibular keratinizing acanthoma)? • An uncommon, benign skin tumor seen in dogs • Unsubstantiated reports in cats • Occurs in dogs younger than 5 years of age • Clinically may have a “rabbit’s foot” appearance 8. What forms does ICE occur in and in what breeds is it seen? Solitary Collie Lhasa Apso Yorkshire Terrier
Generalized Norwegian Elkhound Keeshond German Shepherd Dog Old English Sheepdog
9. What are the treatment modalities available for both types of ICE? Solitary • Surgical excision using conventional methods • Radiation therapy or laser therapy • Cryotherapy is also useful for single, smaller lesions
404
Tumors of Adnexal Origin Multiple • Cryotherapy for a small number of multiple lesions • ICE therapy with vitamin A–related synthetic retinoids (isotretinoin, etretinate, or acretinoin) has been used with some success. • CO2 laser ablation
10. Surveys of hair follicle neoplasia in dogs and cats indicate that these neoplasms account for % of skin tumors? Dogs = 5% Cats = 1% 11. What are neoplasms arising from the region of the hair follicle in the dog and cat? • Tricholemmoma • Trichoepithelioma • Trichoblastoma • Pilomatrixoma 12. With the reclassification of so-called basal cell tumors (see previous chapters), it seems that the majority of previous reports of these neoplasms would currently be classified as what type of neoplasia? Trichoblastoma; therefore, neoplasms of the hair follicle are much more common than recognized in earlier veterinary literature. 13. What are the characteristics of trichoblastomas? • Common • Usually benign • Derived from primitive hair germ cells • Poodle, Cocker Spaniel breeds are predisposed • Solitary, dome shaped firm, 1-2 cm diameter • Occur most commonly on the head, neck, or base of the ear 14. What are the characteristics of trichoepitheliomas? • Usually solitary (Figure 52-1) • Rarely invasive or metastatic (Figure 52-2) • Dorsal lumbar, lateral thoracic, and extremities are common sites. • Basset Hounds, Cocker and English Springer Spaniels, German Shepherd Dogs, Golden Retrievers, Miniature Schnauzers, and Standard Poodles are predisposed.
Figure 52-1 Cross-section of canine trichoepithelioma.
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Figure 52-2 Photomicrograph of canine trichoepithelioma (H&E ×100). 15. What are the characteristics of pilomatrixomas? • Uncommon in dogs, rare in cats • Predilection for neck, shoulders, lateral thorax, and back 16. Breeds predisposed to pilomatrixoma are: • Kerry Blue Terrier • Poodle • Old English Sheepdog 17. On cutting into a cutaneous neoplasm, it is found to be very firm, and the central core shows areas of calcification. This is suggestive of which of the following tumors? (a) Trichoepithelioma (b) Pilomatrixoma (c) ICE (d) Epidermal inclusion cyst (e) Corynebacterium spp. infection Correct answer is (b) Pilomatrixoma 18. Incidence of sebaceous gland tumors, growths arising from sebocytes, is and in cats. • Common in the dog, representing from 6-21% of all canine skin tumors • Uncommon in the cat
in dogs
19. What are the breeds most commonly affected with sebaceous gland tumors? • Beagle • Dachshund • Cocker Spaniel • Miniature Schnauzer • Poodle 20. What is the percent occurrence of the different sebaceous gland tumors and their breed associations (see previous question) and site predilections (if any)? • Nodular sebaceous hyperplasia: 53% • Sebaceous epithelioma: 37%, Shih Tzu, Lhasa Apso, Malamute, Siberian Husky, Irish Setter
406
Tumors of Adnexal Origin
Figure 52-3 Sebaceous gland hyperplasia involving the medial canthus of an English Setter.
Figure 52-4 Nodule consisting of sebaceous gland hyperplasia on the paw of a Cocker Spaniel. • Sebaceous adenoma: 8%, Poodle, eyelid and limbs (Figure 52-3) • Sebaceous carcinoma: 2%, Cocker Spaniel, head and limbs (Figure 52-4) 21. What happens to nodular sebaceous hyperplasia (is there a progression to neoplasia)? Eighty-one percent of sebaceous epitheliomas and 54% of sebaceous adenomas had areas of sebaceous hyperplasia peripheral to and often mixing into neoplastic areas. These findings suggest that sebaceous hyperplasia may be a precursor to sebaceous epitheliomas and adenomas. 22. Which of the following statements is most correct regarding sebaceous gland tumors in the dog? (a) All sebaceous glands are malignant (b) Show no age or breed predilection; majority of tumors are malignant (c) Mostly in older, giant breed dogs; majority of tumors are benign (d) Mostly in older small breed dogs; majority of tumors are benign Correct answer is (d)
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23. Which of the following statements regarding perianal (hepatoid) gland tumors is correct? (a) Malignant, most commonly arise in the perianal areas of older male dogs (b) Benign, most commonly arise in the perianal areas of older male dogs (c) Malignant, most commonly arise in the perianal areas of older female dogs (d) Benign, most commonly arise in the perianal areas of older female dogs Correct answer is (b) 24. Perianal (hepatoid) glandular tissue may be found on the dog around the: (a) Anus (d) Skin of the lumbar and sacral areas (b) Prepuce (e) All of the above (c) Dorsal area of the tail Correct answer is (e) 25. What are therapeutic choices when treating perianal (hepatoid) gland adenomas? (a) Castration is probably the single best initial choice. Tumors may regress spontaneously over the 1- to 2-month postoperative period or reduce greatly in size, making surgical removal easier. (b) Cryosurgery is used primarily for tumors that are less than 1-2 cm in diameter. (c) Systemic administration of long-acting estrogenic compounds has been used before surgical debulking, but chronic use runs a substantial risk of bone marrow suppression. (d) External beam radiation therapy has been reported in the treatment of benign and malignant perianal/anal tumors but is used as more of a last resort due to increased cost and possible morbidity associated with procedure. 26. Is there a gender predilection for perianal gland adenomas and adenocarcinomas in the dog? Perianal gland adenomas are nine times more common in male than in female dogs (Figure 52-5). Perianal gland adenocarcinomas occur with equal frequency in both sexes (Figure 52-6). 27. How do circumanal gland (apocrine) carcinomas differ in their disease progression compared to perianal gland adenomas? • Grow more rapidly • Grow larger • Ulcerate 28. Are there prognostic indicators for dogs with perianal tumors? Yes, Tumor Size • Dogs with lesions greater than 5 cm. have an 11-fold higher risk of dying of tumor-related causes; in particular, metastasis to sacral and sublumbar lymph nodes. • Metastasis occurs in approximately 30% of cases. 29. How common are apocrine gland neoplasms of the dog and cat? • Primary apocrine gland neoplasia is rare in dogs (approximately 2% of all skin tumors) • More common in cats than sebaceous gland tumors. • Adenocarcinomas are more common than adenomas (50-90% malignant). • There are two modified apocrine gland tumors, ceruminous gland tumors of the ear and apocrine gland tumors of the anal sac, that are more commonly seen in the veterinary patient. 30. What clinical features are consistently helpful in differentiating histologically benign from histologically malignant tumors? • There are no clinical features that help.
408
Tumors of Adnexal Origin
Figure 52-5 Perianal adenoma in an intact male dog.
Figure 52-6 Perianal adenocarcinoma in an intact female dog.
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• Therefore, another reason for excisional biopsies with wide surgical margins. • Unfortunately a common area on which adnexal tumors grow are the limbs; therefore making complete surgical removal a more difficult, sometimes impossible procedure. Tissue flap/plastic procedures, radiation, or limb amputation would then be considered. • However, incisional biopsy before aggressive surgery or adjunctive procedures is always recommended. 31. What are some special stains that can sometimes differentiate apocrine (epitrichial) adenomas from adenocarcinomas? • Apocrine sweat gland (epitrichial) tumors are positive for cytokeratins. • Carcinomas, not adenomas, are positive for carcinoembryonic antigen (secretory cell) and vimentin (myoepithelial cell). 32. What are the most common neoplasms of the ear canal? • Inflammatory polyps • Papillomas • Basal cell tumors • Ceruminous gland adenomas (Figure 52-7)
Figure 52-7 Ceruminous gland adenoma (1 cm diameter) and ceruminous cysts (1 mm diameter) in the external ear canal of a cat.
• Common malignant tumors found in the ear canal include ceruminous gland adenocarcinoma, squamous cell carcinoma, and carcinoma of undetermined origin. 33. What are the most common ear pinnal neoplasms? DOG Sebaceous gland tumors Histiocytoma Mast cell tumor Melanocytic neoplasms
CAT Squamous cell carcinoma Basal cell tumor Hemangiosarcoma
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34. Are ceruminal gland tumors usually benign? • Dog: ceruminal gland tumors are typically benign • Cat: ceruminal gland tumors are malignant in 50% of cases 35. What are common clinical observations in animals with ear canal tumors? • Older animals • Unilateral involvement only • Head scratching/head-shaking behavior • Frequent secondary bacterial/yeast infections with no history of problems • Aural discharge and/or intermittent hemorrhage from affected ear • Occasionally cause bulging, ulceration/draining mass below ear in the parotid region of the skull • Neurologic signs (peripheral vestibular disease, facial nerve paresis, Horner’s syndrome) are noted in approximately 10% of dogs and approximately 25% of cats with ear canal tumors. 36. What does proper clinical staging of an ear canal–based tumor include? • Minimum database (complete blood cell count, serum biochemistry, urinalysis) • Thoracic radiography • Fine needle aspirate or excisional biopsy of local lymph nodes • Radiologic study of the skull: computed tomography of the ear canal and tympanic bullae is recommended due to improved ability to evaluate soft tissue and bony changes and evidence of local extension. Skull radiographs may be used to evaluate primarily for evidence of bony changes and superimposition of anatomic structures may occur. • Incisional biopsy may be recommended in cases of suspected neoplasia if owners are considering adjunctive therapies instead of primary surgical excision. 37. What is the only effective therapy for an ear canal–based ceruminal tumor? • Complete surgical excision, usually by lateral ear resection or total ear canal ablation (TECA) • The best results are achieved with TECA and lateral bulla osteotomy. • The approximate recurrence rate for ceruminous gland tumors after lateral ear resection is 70%. 38. What is the most common signalment for anal sac gland tumors (apocrine)? Older female dogs, often associated with hypercalcemia of malignancy (PTHrP). 39. In a female dog, which of the following tumors is most likely to show metastasis to regional lymph nodes? (a) Anal gland tumor (b) Squamous cell carcinoma (c) Papilloma (d) Intracutaneous cornifying epithelioma Correct answer is (a) 40. What are common clinical signs noted in animals afflicted with anal sac adenocarcinoma? • Palpable rectal mass noted in the region of the anal sac • Perineal swelling • Tenesmus • Constipation/obstipation • Change in the shape of stool • Polyuria/polydipsia (associated with hypercalcemia)
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41. What does the recommended clinical staging of an anal sac tumor include? • Minimum database (complete blood cell count, serum chemistry, urinalysis) • Thoracic radiography (low yield procedure) • Abdominal imaging to evaluate regional lymph nodes • In general, ultrasonography of the abdomen is considered superior to caudal abdominal radiography for examination of regional lymphadenomegaly. • Rectal examination • Exfoliative cytology of this region is usually unrewarding in differentiation between benign and malignant processes in this region. 42. What is the general prognosis for animals with anal sac apocrine gland adenocarcinoma? • In general, the prognosis is poor; mean survival times for females is approximately 12 months with local recurrence occurring in approximately 50% of operated cases. • Metastasis and hypercalcemia are both considered poor prognostic indicators (approximate 6-month survival vs 12-month survival times). 43. What are adjunctive therapies for anal sac adenocarcinoma? External beam radiation has been offered as a monotherapy or as adjunctive therapy in cases of incomplete resection with variable results. The efficacy for this tumor is unknown, but in most cases chemotherapeutic agents have not been useful as an adjunctive therapy. One study revealed partial remission in approximately 30% of dogs using the platinum compounds. 44. Eccrine (atrichial) sweat gland tumors of the dog and cat: • May be benign or malignant in the dog • Almost always malignant in the cat • Are restricted to locations on the paw pads or digits BIBLIOGRAPHY Bevier DE, Goldschmidt MH: Skin tumors in the dog. I. Epithelial tumors and tumor like lesions, Compend Cont Ed Small Anim Vet Med 3(5):389-399, 1981. Bevier DE, Goldschmidt MH: Skin tumors in the dog. II. Tumors of the soft (mesenchymal) tissues, Compend Cont Ed Small Anim Vet Med 3(6):506-520, 1981. Cowell RL, Tyler RD, Meinkoth JH: Diagnostic cytology and hematology of the dog and cat. ed 2, St. Louis, 1999, Mosby. Fitzpatrick JE, Aeling JL (eds): Dermatology secrets in color, ed 2. Philadelphia, 2001, Hanley & Belfus. Goldschmidt MH, Bevier DE: Skin tumors in the dog. Part III: lymphohistiocytic and melanocytic tumors, Compend Cont Ed Small Anim Vet Med 3:588-597, 1981. Goldschmidt MH, Dunstan RW, Stannard AA, von Tscharner C, et al: Histological classification of epithelial and melanocytic tumors of the skin of domestic animals, AFIP, Am Reg Pathol WHO (series 2), vol 3, Washington, DC, 1998. Goldschmidt MH, Shofer FA: Skin tumors of the dog and cat. Oxford, 1992, Pergamon. Gross TL, Ihrke PJ, Walder EJ: Veterinary dermatopathology: a macroscopic and microscopic evaluation of canine and feline skin disease, St Louis, 1992, Mosby. Scott DW, Miller WH, Griffin CE: Muller & Kirk’s small animal dermatology, ed 6. Philadelphia, 2000, WB Saunders.