Lecture 10 - Mast Cell Tumors Flashcards
Charlie - PE
Integument: 3x2 cm alopecia, erythematous mass with focal areas of ulceration comprising digit 4 of right front paw, extending cranially over digit 5. Reactive to palpation of paw, no active bleeding noted
Lymph nodes: Right prescapular lymph node enlarged and firm (2 cm)
Problem List?
- Mass of 4th digit of the right front paw
- Enlarged right prescapular lymph node
Charlie - PE
- Mass of 4th digit of the right front paw
- Enlarged right prescapular lymph node
Differential list?
- Infectious (bacterial, fungal), Inflammatory (sterile pododermatitis), Neoplasia (lymphoma)
- Infectious, Inflammatory, Neoplastic (primary or metastatic)
Charlie
Integument: 3x2 cm alopecia, erythematous mass with focal areas of ulceration comprising digit 4 of right front paw, extending cranially over digit 5. Reactive to palpation of paw, no active bleeding noted
Lymph nodes: Right prescapular lymph node enlarged and firm (2 cm)
Diagnostic tests?
- Fine needle aspirate & Cytology – digit mass
Charlie
Fine needle aspirate & Cytology – digit mass
Results:
- Your clinical pathologist looks at the cytology samples that you digitally sent them and tells you that there is mixed inflammation present, highlighted by the presence of non-degenerate neutrophils, macrophages, eosinophils, and occasional lymphoblasts.
- However, there also appears to be a population of monomorphic round cells displaying some criteria of malignancy (anisocytosis, anisokaryosis, prominent nucleoli). These could be secondary to inflammation or an underlying neoplastic process
- What would be the ideal next step?
- And the potential next diagnostic test?
- Incisional biopsy
- aspirate/biopsy of prescapular lymph node
Charlie - diagnostic tests?
Prescapular lymph node aspirate results:
- Lymphoid cells consist predominantly of mature small lymphocytes with mild numbers of intermediate lymphocytes and occasional large lymphocytes. Occasional plasma cells are visible. No infectious etiologies are identified.
- Interpretation:
- Metastatic mast cell neoplasia
- Mild to moderate eosinophilic inflammation
- Mild reactive lymphoid tissue
Extra card
- Immune cells present in many tissues throughout the body - often. in areas where the “outside world” comes into contact with the body
- Skin, GI tract, respiratory tract, etc - Part of the innate immune system
- Protection against parasitic infections
- Venom detoxification
- Involved in regulating the functions of many organs and tissues
Mast cell Tumors
Mast cell mediators cause local and systematic hypersensitivity such as (list them):
- Vasodilation, increased vascular permeability
- Smooth muscle spasm
- Pruritis
- Anti-coagulation
What is the most common cutaneous tumor in dogs?
Mast Cell Tumor
- 16-21% of all skin tumors
(T/F) Mast cell tumors are mostly a disease of older dogs (mean age 8-9 years)
True
List Cutaneous MCT sites from most likely to least likely:
- Trunk & perineal
- Limbs
- Head & neck
What is generally a sufficient diagnosis for MCT?
Cytology
- Mast cells
- Variable granule staining
- Eosinophils
- Fibroblasts
List the well-established prognostic factors:
- Breed
- Biologic Behavior (how are they acting at home)
- Anatomic Location
- Clinical Stage (where in the body)
- Histopathologic Grade (most predictive)
- KIT mutation
(T/F) Brachycephalic breeds are predisposed to developing mast cell tumor, however they tend to behave in a more benign fashion
True
What breed is known for developing high-grade/more aggressive mast cell tumors?
Shar Peis
Prognostic Factors – Biologic Behavior
- Slow growing
- Present without changing for a long period of time (6+ months)
- Dog otherwise feeling well
Good
Prognostic Factors – Biologic Behavior
- Rapid Growth
- Ulceration, erythema, pruritis
- Recurrence
- Systemic signs
- Vomiting/Diarrhea
- Melena
Bad
Prognostic Factors – Anatomic Location
- Generally, behave in a more benign fashion
- Low recurrence rates (8%) and metastatic rate (4%)
Subcutaneous MCT
Prognostic Factors – Anatomic Location
- 50-60% have LN metastasis at diagnosis
- Can still have prolonged survival (>1 year)
Muzzle MCT
Prognostic Factors – Anatomic Location
- Historically have all been thought to act more aggressively
- Oral
- Preputial
- Perineal
- Nailbed
- Inguinal MCT
Prognostic Factors – Anatomic Location
- Liver, spleen, GI tract, Bone marrow
- Poor Prognosis
Visceral MCT
If mast cell tumors are going to metastasize, where do they most commonly spread?
- Locoregional – local/draining lymph node
- Distant metastasis – visceral organs (Spleen, Liver)
- Lungs are VERY RARE
