Pathology: Skin Neoplastic + Non-Neoplastic Tumors

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Questions and Answers

What is the primary concern for clients regarding skin masses on their pets?

They are mostly benign.

They can lead to skin metastases.

They are commonly caused by infections.

They may require expensive treatments. (correct)

Neoplasms from other body parts frequently develop skin metastases.

False

What is the most valuable initial diagnostic test when investigating a skin tumor?

cytology

The advantages of cytology include its low cost and short time required to obtain results. Cytology samples are stained using a __________ stain.

diff-quik Signup and view all the answers

Match the following terms related to skin tumors with their definitions:

Cytology = A diagnostic method for evaluating tumors Fine needle aspiration = A technique to obtain a sample from a tumor Excision = Surgical removal of a tumor Chemotherapy = Treatment using drugs to eliminate cancer cells Signup and view all the answers

Which of the following is NOT a potential treatment plan for skin tumors?

Immunotherapy Signup and view all the answers

It takes more than 10 minutes to provide a diagnosis from cytology if the clinician interprets the slides themselves.

False Signup and view all the answers

What skill is valuable for a companion animal clinician in relation to skin tumors?

Diagnosing by cytology Signup and view all the answers

What is the most common canine skin tumor?

Histiocytoma Signup and view all the answers

Lipomas are a malignant form of skin tumor.

False Signup and view all the answers

What triggers the dystrophic calcification seen in Calcinosis circumscripta?

Trauma Signup and view all the answers

Canine cutaneous histiocytomas typically resolve in _____ weeks.

2-4 Signup and view all the answers

Match the following dog breeds with their associated conditions:

Burnese Mountain Dog = Systemic Histiocytosis German Shepherd = Calcinosis circumscripta Rottweiler = Systemic Histiocytosis Young dogs = Histiocytoma Signup and view all the answers

What is the typical appearance of a lipoma upon palpation?

Soft and movable Signup and view all the answers

Systemic histiocytosis is a benign condition found in dogs.

False Signup and view all the answers

What type of cells are primarily involved in canine cutaneous histiocytomas?

Histiocytes Signup and view all the answers

Hemangiomas are commonly located on the _____ abdomen and medial thighs.

ventral Signup and view all the answers

Match the following tumors with their descriptions:

Histiocytoma = Rapidly growing, usually resolves in weeks Lipoma = Soft, mobile fatty mass Hemangioma = Dark purple mass, solar induced Calcinosis circumscripta = Nodular mass over bony prominences Signup and view all the answers

Which tumor requires histological examination for differential diagnosis?

Hemangioma Signup and view all the answers

Histiocytomas can be confused with systemic histiocytosis because they both involve histiocytes.

True Signup and view all the answers

What is a characteristic feature of the cytology of a lipoma?

Fat globules Signup and view all the answers

An infiltrative lipoma can be challenging to diagnose as it infiltrates through _____ muscle.

skeletal Signup and view all the answers

Which tumor type should be removed immediately according to its urgency?

Hemangiopericytoma Signup and view all the answers

Cytology is always sufficient for a definitive diagnosis of all tumor types.

False Signup and view all the answers

What is the most common cutaneous neoplasm with malignant potential in dogs?

Mast cell tumors Signup and view all the answers

Histiocytoma, lipoma, follicular cyst, sebaceous hyperplasia, and basal cell tumor are all examples of __________ in dogs.

benign skin tumors Signup and view all the answers

Match the following tumor types with their characteristics:

Sebaceous gland hyperplasia = Often appears wart-like and can be multifocal Follicular cyst = Develops from malformed hair follicles Nevus = Increased quantities of normal collagen Mast cell tumor = Common neoplasm with malignant potential in dogs Signup and view all the answers

Which of the following tumors can resolve spontaneously?

Inflammatory tumors Signup and view all the answers

Histology is more expensive than cytology.

True Signup and view all the answers

What is the main disadvantage of using cytology over histology?

Cytology may not definitively diagnose all tumor types. Signup and view all the answers

The __________ are often located on the eyelids and are common in older dogs.

sebaceous gland hyperplasia Signup and view all the answers

Match the following tumor types with their most common animal group:

Histiocytoma = Dogs Squamous cell carcinoma = Cats Follicular cysts = Dogs and Cats Basal cell tumors = Cats Signup and view all the answers

Which animal breed is mentioned as being commonly affected by sebaceous gland hyperplasia?

Beagles Signup and view all the answers

Mast cell tumors are the 5th most common canine skin tumor.

False Signup and view all the answers

What type of tumors are inflammatory tumors and what can cause them?

Inflammatory tumors can be caused by bacteria, fungi, viruses, or trauma. Signup and view all the answers

Aspiration of a follicular cyst reveals __________ material.

cloudy grey/brown Signup and view all the answers

What is a critical differentiator between sebaceous adenomas and sebaceous gland hyperplasia?

Size of the tumor mass Signup and view all the answers

What percentage of all canine skin neoplasms do benign sebaceous and apocrine gland tumors constitute?

10% Signup and view all the answers

Sebaceous gland epitheliomas are more common than sebaceous gland adenomas.

False Signup and view all the answers

Which type of benign neoplasm is characterized by large, foamy looking cells?

Sebaceous gland adenomas Signup and view all the answers

Complete excision is __________ for benign sebaceous and apocrine gland tumors.

curative Signup and view all the answers

Where are sebaceous gland adenomas most commonly found?

Eyelids, limbs, and trunk Signup and view all the answers

Squamous cell carcinoma is the most common malignant epithelial neoplasm in dogs.

True Signup and view all the answers

What is a characteristic feature of squamous cell carcinoma cells?

Large, angular, keratinized cells with retained nuclei Signup and view all the answers

Hepatoid gland adenomas are derived from modified __________ glands surrounding the rectum.

sebaceous Signup and view all the answers

What type of neoplasm is often confused with apocrine gland adenocarcinomas?

Hepatoid gland adenomas Signup and view all the answers

Castration of a dog may lead to regression of hepatocellular adenomas.

True Signup and view all the answers

What are the three subtypes of follicular neoplasms?

Trichoepithelioma, pilomatricoma, and intracutaneous cornifying epithelioma. Signup and view all the answers

Sebaceous gland adenomas that develop on the eyelids are also referred to as __________ gland adenomas.

Meibomian Signup and view all the answers

Match the following types of tumors with their description:

Sebaceous gland adenoma = Well-differentiated sebaceous cells Basal cell tumor = Derived from follicular basal cells Squamous cell carcinoma = Most common malignant epithelial neoplasm Hepatoid gland adenoma = Resembles hepatocytes Signup and view all the answers

Which type of tumor is known for being highly invasive and quick to metastasize?

Apocrine gland adenocarcinoma of anal sac origin Signup and view all the answers

What is suggested about the metastatic lesions in grey horses with lesions?

They represent a storage disease. Signup and view all the answers

Equine sarcoids tend to metastasize and are easily excised.

False Signup and view all the answers

What common cause is linked to cutaneous hemangiosarcomas in dogs?

Sunlight exposure Signup and view all the answers

The most common skin tumor of horses is called ________.

equine sarcoid Signup and view all the answers

Which type of cells are often revealed through cytology of equine sarcoids?

Spindle-shaped cells Signup and view all the answers

Dogs with cutaneous hemangiosarcomas typically do not develop multiple neoplasms.

False Signup and view all the answers

What virus is currently thought to be associated with the development of equine sarcoids?

Bovine papillomavirus (BPV) Signup and view all the answers

Match the following tumors with their characteristics:

Grey horse lesions = Do not typically cause clinical signs Cutaneous hemangiosarcoma = Induced by sunlight exposure Equine sarcoid = Caused by bovine papillomavirus Canine hemangiosarcoma = Usually metastasizes late in clinical course Signup and view all the answers

What types of neoplasms can develop on the external skin of the anus?

Hepatoid gland adenomas Signup and view all the answers

Apocrine gland adenocarcinomas are benign and do not metastasize.

False Signup and view all the answers

What is the primary systemic effect of hepatoid gland adenomas?

There are no systemic effects. Signup and view all the answers

Canine mammary neoplasms often consist of glandular and ductular structures lined by __________ cells.

anaplastic Signup and view all the answers

Match the following tumor types with their descriptions:

Hepatoid gland adenomas = Benign, testosterone-responsive Apocrine gland adenocarcinomas = Infiltrative and metastatic Mammary gland tumors in dogs = 50-80% benign Feline mammary adenocarcinomas = Rapidly metastasizes Signup and view all the answers

What is one of the benefits of early spaying in dogs?

Reduces the risk of mammary neoplasia Signup and view all the answers

Most canine mast cell tumors are associated with a grave prognosis.

False Signup and view all the answers

What is the easiest feature to recognize cytologically in mast cell tumors?

Presence of dark purple granules Signup and view all the answers

Cytology tends to be a poor predictor of the behavior of __________ tumors.

mast cell Signup and view all the answers

What is the most critical prognostic factor in feline mammary gland neoplasia?

Size of the neoplasm Signup and view all the answers

Castration prevents the development of testicular tumors in dogs.

True Signup and view all the answers

Which dog breeds are predisposed to mast cell tumors?

Labradors, Boxers, Shar Peis, Boston Terriers, Pugs Signup and view all the answers

Feline mammary adenocarcinomas often metastasize via __________.

lymphatics Signup and view all the answers

What percentage of mammary neoplasms in dogs are considered benign?

50-80% Signup and view all the answers

Match the following terms with their definitions:

Cytology = Study of cells Histology = Study of tissues Benign = Non-cancerous Malignant = Cancerous Signup and view all the answers

What is the nature of feline cutaneous mast cell tumors (MCTs)?

Benign neoplasms that do not metastasize Signup and view all the answers

MCTs that develop in the gastrointestinal tract of cats are benign.

False Signup and view all the answers

What is the common treatment method for feline cutaneous MCTs?

Excision Signup and view all the answers

Equine MCTs are more likely to be __________ than neoplastic.

hyperplastic Signup and view all the answers

Match the tumor type to its primary characteristic:

Feline cutaneous MCTs = Almost invariably benign Equine MCTs = More likely hyperplastic Plasmacytomas in cats = Guarded prognosis Dermal melanoma in dogs = Most common on eyelids Signup and view all the answers

Which of the following statements about dermal melanomas in dogs is correct?

Cutaneous melanomas can develop anywhere but are common on the eyelids Signup and view all the answers

Cutaneous plasmacytomas in dogs are rarely associated with multiple myeloma.

True Signup and view all the answers

What is the characteristic appearance of the nucleus in cells of a plasmacytoma?

Clock-face nucleus Signup and view all the answers

Approximately _____% of dogs with nail-bed melanomas will have developed metastases by diagnosis.

30 Signup and view all the answers

Match the following terms with their descriptions:

Soft tissue sarcoma = Infiltrative and can metastasize Equine collagenolytic granuloma = Confused with equine MCTs Dermal melanoma = Common in dogs, cats, and horses Feline plasmacytoma = More commonly develops on lower limbs Signup and view all the answers

What percentage of cutaneous plasmacytomas may recur after excision?

10% Signup and view all the answers

Surgical excision of dermal melanoma in dogs is usually curative if done correctly.

True Signup and view all the answers

Name one common location for plasmacytomas to develop in dogs.

Mouth Signup and view all the answers

Soft tissue sarcomas can metastasize, but more frequently result in __________ recurrence.

local Signup and view all the answers

What is a common misconception regarding equine mast cell tumors?

They do not develop in horses Signup and view all the answers

Study Notes

Neoplastic Tumors

Skin masses are commonly seen in companion animals and pose both diagnostic challenges and economic opportunities for veterinarians.
Primary skin neoplasms are more prevalent than metastatic neoplasms from other body sites.
Definitive diagnosis is crucial for selecting appropriate treatment, which can include observation, surgical excision, or chemotherapy.
Cytology is the primary diagnostic test for skin tumors, often using fine needle aspiration.
For surface-oriented masses, such as squamous cell carcinomas, tissue scrapes may be more effective than aspiration.
Cytology is cost-effective, requires no sedation, and provides rapid results, typically within 24 hours if sent to a laboratory.
Differentiating between inflammatory and neoplastic processes is important for treatment planning and client communication.
The most common benign skin tumors in dogs include histiocytomas, lipomas, follicular cysts, sebaceous hyperplasia/adenomas, and basal cell tumors.
Malignant potential in skin tumors is primarily associated with mast cell tumors, which rank sixth among common canine skin tumors.

Non-Neoplastic Tumors

Non-neoplastic tumors arise from non-neoplastic cells and can either resolve spontaneously or require surgical excision.
Inflammatory tumors may result from bacterial, viral, or fungal infections, or trauma, and can often be treated conservatively.
Nevus (focal adnexal hyperplasia) consists of benign collagen or adnexa and requires excision only if symptomatic.
Sebaceous gland hyperplasia frequently occurs in certain dog breeds and appears as wart-like growths; excision is curative but multiple lesions may develop over time.
Follicular cysts (dermal cysts) form from malformed hair follicles that trap keratin, often leading to inflammation and possible rupture.
Calcinosis circumscripta develops as a nodular mass, predominantly in young large breed dogs, resulting from dystrophic calcification due to trauma.

Possibly Neoplastic Tumors

Canine cutaneous histiocytomas are the most common benign skin tumors in dogs, characterized by localized histiocyte proliferation with spontaneous resolution in weeks.
Lipomas, subcutaneous fat deposits, are the second most common skin tumor, typically mobile and benign, requiring excision only if they interfere with function.
Hemangiomas are well-differentiated vascular tumors, often associated with solar exposure; complete excision is curative.

Primary Skin Neoplasms

Epithelial neoplasms arise from skin adnexal structures and are classified as adenomas (benign) or adenocarcinomas (malignant).
Benign sebaceous and apocrine gland adenomas account for 10% of canine skin neoplasms and are commonly found on eyelids, limbs, and trunk.
Basal cell tumors, common in dogs, cats, and horses, arise from follicular basal cells and can be pigmented; excision is curative.
Follicular neoplasms include trichoepithelioma, pilomatricoma, and intracutaneous cornifying epithelioma and are mainly benign.
Squamous cell carcinoma is the most common malignant epithelial neoplasm, particularly in cats, linked to UV exposure and presenting as ulcerated lesions.
Hepatoid gland adenomas, testosterone-responsive skin tumors in dogs, resemble hepatocytes on cytology and are most common in uncastrated males.### Hepatoid Gland Adenomas vs. Apocrine Gland Adenocarcinomas
Hepatoid gland adenomas develop externally around the anus, detectable by touch.
Apocrine gland adenocarcinomas arise within the anal sacs, presenting as diffuse perineal swelling.
Hepatoid gland adenomas are benign, testosterone-responsive, with no systemic effects.
Apocrine gland adenocarcinomas can produce PTH-rp, are infiltrative, metastatic, and often fatal.
Castration reduces the likelihood of hepatoid gland adenomas, prostatic disorders, and testicular tumors.

Mammary Gland Tumors in Dogs and Cats

Common in both dogs (50-80% benign) and cats (almost always malignant).
Early spaying significantly lowers the risk of mammary neoplasms in dogs.
Canine mammary tumors often feature glandular structures with anaplastic cells, and bone and cartilage may be present.
Tumors that are harder and more nodular tend to be benign.
Cytology is often inadequate for differentiating mammary adenomas from adenocarcinomas.
Feline mammary adenocarcinomas metastasize quickly and may spread to skin.
Tumor size is critical for prognosis in cats; larger tumors indicate worse outcomes.
Early spaying does not impact mammary cancer risk in cats.

Round Cell Neoplasms

Round cells originate in the bone marrow and travel to skin, losing mobility upon settling.
Low interaction between these cells leads to distinct cytological features.

Mast Cell Tumors (MCTs)

MCTs are the 6th most common tumors in dogs and 21% of feline skin tumors.
Nearly all feline MCTs are benign, while canine MCTs can be malignant with variable behavior.
Diagnosis typically via cytology, revealing round cells with dark purple granules.
Canine MCTs can be low or high grade based on histological invasion and differentiation.
Low-grade canine MCT removal is often curative; however, recurrence occurs in 5-15%.
High-grade MCTs have poorer prognoses and can metastasize early.
Feline cutaneous MCTs are usually benign and localized; surgical excision is curative.

Cutaneous Plasmacytoma

Occur in dogs mainly in the mouth, feet, and pinnae; rare in cats.
Cytology shows non-cohesive round cells with a characteristic ‘clock-face’ nucleus.
Generally do not recur locally, but new plasmacytomas may arise.
Cats are more likely to develop plasmacytomas linked to multiple myeloma, which affects prognosis.

Spindle Cell Tumors

Develop from connective tissue; soft tissue sarcomas are a common type in dogs.
Cytology often shows spindle-shaped cells within visible bundles.
Can be infiltrative despite seeming encapsulated; local recurrence is about 30%.
Complete excision attempts should prioritize wide margins to reduce recurrence risks.

Dermal Melanoma

Common in dogs, its behavior varies depending on skin location.
Non-haired skin melanomas (e.g., nail-bed, mucocutaneous junction) are generally malignant.
Canine melanomas on haired skin are often benign; complete excision is typically curative.
Feline and equine melanomas are often malignant and affirmatively require careful monitoring.

Cutaneous Hemangiosarcoma

Primarily affects older dogs, induced by sunlight; often found on the ventrum.
Typically, only metastasize late in progression; multiple lesions can develop.
Excision is usually effective, but preventive measures against sun exposure are imperative.

Equine Sarcoid

Most common skin tumor in horses, associated with bovine papillomavirus (BPV).
Develops variably in clinical presentation, usually in trauma-prone areas.
Cytology reveals spindle-shaped cells, while histology shows fibroblast proliferation without metastasis.
Local recurrence is common, and treatment remains inconsistent.

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Description

This quiz focuses on the identification and implications of neoplastic and non-neoplastic tumors, particularly those that develop on the skin of companion animals. Understanding these masses is crucial for veterinarians to provide appropriate treatment plans and effectively address client concerns. Test your knowledge on this important topic in veterinary medicine.