Mast Cell Tumors in Dogs: Diagnosis & Treatment PDF

Mast Cell Tumors David Hunley, DVM, DACVIM (Oncology) Canine MCTs ► Cell of origin – Mast Cell Altrui Cens Function - ► L ► Wound healing ► Induction of innate immune re...

Mast Cell Tumors David Hunley, DVM, DACVIM (Oncology) Canine MCTs ► Cell of origin – Mast Cell Altrui Cens Function - ► L ► Wound healing ► Induction of innate immune response ► Antiparasite activity CAMINEOSINOIS > - ► Modulation of reaction to insect and spider venoms ► Mast cells contain Caranues) D ► Heparin BLEED ALOT WHEN ASPIRATED Canticonaucant) > - D► Histamine P ► Eosinophil chemotactic factor ► Proteases (chymase, tryptase) Canine MCTs ► Typical presentation ► Cutaneous mass ► Variety of clinical appearances (slow growing, non-ulcerated to rapidly-growing, large, ulcerated masses) ► May wax and wane in size Duemanot > Histamine (intermination r sucre) to (smal Size Are tre size or timo) - - Actually beGnomim ► May be ulcerated, erythematous and/or pruritic ► Will bleed or enlarge when aspirated D CAN LOOK UKEArthrD ► All due to histamine/heparin release IMITATOR - (degranulation) - MAY Ever Look LIKEASKINTAS ► Can occur in any breed ► Common in Bulldog decent, labs, goldens, DBOXENSY cockers, schnauzers, pits, beagles, shar-peis - Bracceptance (pras)  Canine MCTs ► Typical presentation ► 10-15% have multiple cutaneous lesions ► Can occur in the conjunctiva, nasopharynx, larynx, oral cavity ► Can occur in visceral or disseminated form  Canine MCTs DDONT USUALY SEE VISCINAL MCT = IFSO , ITS P Cause of ► Testing METASTASIS ► FNA of mass ► Usually diagnostic ► Many purple (metachromatic) granules ► Sometimes poorly-granulated ► Granules may not show up as well with Diff-Quik usual - ► Granules contain histamine WORKS FINE ► Released (degranulation) ► CBC/chem/UA > DOESN'T USUALY PICK UP - CANCER Word Be Normal - ► Often no significant changes usual - UNLESS Para Neoplastic ► May see eosinophilia DZ D cus of less arances are more acranissive to  Canine MCTs ► Testing ► Abdominal US ↓ metastasis is usual D IN These 3 D ► Hepatomegaly D ► Splenomegaly D ► Enlarged lymph node (sublumbar for MCT on hind limbs) ► Thoracic rads ► Rare pulmonary parenchymal involvement ► May see enlarged sternal lymph node  DUAMable Size Mc & LMPHOCUESD Canine MCTs ► Testing ► Regional lymph node evaluation ► Definitive criteria for metastatic disease can be challenging if mast cells are present in low numbers because mast cells are normally found in lymph nodes A and their numbers can be increased in the presence of infection and ulceration ► Occasional, solitary mast cells are not indicative of * FIND UN Close to MCTD metastasis D ► Clustering, aggregates, abnormal morphology are more b concerning - POOm GRANUATed (METASTASIS UKEM) IS More ► May need to removal node for histologic confirmation D ► Weishaar Nodal Classification System > - To DETERMINE If tre METASTASis ► HN0, HN1, HN2, HN3 ► US guided aspiration of liver and spleen ► I do not recommend aspiration of normal appearing liver and spleen ↓ JAPAN - Smace Docs UNLESS HAS VERY AGGNSSIV MCT GI MAST Car - - tors.  Canine MCTs ► Testing ► Biopsy of mass D DON'T CUT INTOTHEMD ► Generally post-surgery ~ vv ► Degranulation from incisional biopsy ► Surgical margins ► Tend to be invasive, so difficult to achieve wide surgical margins - LOUD HA DENDRIT UNES GOING DOWN - NEED WIDE mrhINS  Canine MCTs ► Testing ► Biopsy of mass ► Tumor grade ► Old grading system (Patnaik) ► Grade 1-3 ► Subjective criteria for pathologists ► Most come back as grade 2 ► High grade 2 and low grade 2 ► Mitotic index ( - LOW GRADE 2 ► Prognostic panels (several variables)  Canine MCTs ► Testing ► Biopsy of mass ► Tumor grade ► New grading system (Kiupel) ► “Two-tier” grading system ► More objective histologic criteria D ► Mitotic figures, multinucleation, “bizarre” & nuclei, karyomegaly - ABLE TO IDENTIFY & Count ► Low grade or High grade Lust two options) > - HPFUL For CHENT UNDERSTANDIN ► Median survival time: > 2 years for low grade, < 4 months for high grade  Canine MCTs ► Testing ► Biopsy of mass ► Tumor grade ► My experience with the two-tier grading system ► Skeptical at first, but now I like it! ► More agreement among pathologists ► Seems to be accurate ► Easy for clients ► Reasonable to use as the sole predictor of metastatic potential ► Nothing’s 100%  Normal Canine MCTs - Sizz NOTOF - CONANURES - CONGUADE ► Testing ► Cytologic grading ► Grading based on degree of granulation and cell morphology MANY DIFF Pretty good correlation with -. ► Sizes histologic grading - Une GRANUES ► Maybe recommend staging more strongly prior to surgery  Canine MCTs ► Testing ► MCT prognostic panel ► Attempt to gain more insight into tumors of borderline grade ► Proteins/Genes Evaluated ► Ki67 Go Up = Cers Abort TO DLUDE ► AgNORs ► c-Kit protein (KIT) staining pattern > not coop?? - - More AcrinEssice D ► c-kit mutational status (PCR) > MOSINE - KINASE Receptor ► Could help guide treatment decisions ► Varying opinions on usefulness Canine MCTs ► Prognosis ► Wide range of potential outcomes remove of tumor ► Low grade MCTs will often live years > -EeN of no ► High grade MCTs will sometimes metastasize in weeks ► Notoriously unpredictable important ! D► Tumor grade is the most important prognostic factor ↳ > - 2 Her most ► Mitotic count ( - PROB GOT. IT ALL OUT BUT STIL MAY COME BACK ► Can be difficult to achieve wide margins in some sites (distal limbs, muzzle, etc.) ► Local tumor regrowth occurs frequently, but… ► Low grade MCTs often do not recur even if they are incompletely resected D JUST WATCH TO SEE IF GROW BACK D Canine MCTs ► Treatment ► Radiation therapy -LOCAL MENARY FOR LOCALD2D ► Definitive therapy for incompletely resected tumors ► Not if there is distant metastasis ► High grade tumors? ► 95% 5-year survival (Grade II) ► But now we know many do well with no therapy ► Palliative therapy for large, non-resectable masses - AllowsSome StrnkA ► 8 Gy x 4 doses ► Cutaneous, lymph nodes Canine MCTs ► Treatment ► Systemic therapy ► High grade tumors after resection ► When metastasis is present ► Non-resectable tumors ► Multiple cutaneous tumors D ► Prednisone, Diphenhydramine, Famotidine D ► If gross disease is present ► Chemotherapy - Monteradicate it/not Merely Good D ► CCNU ► Vinblastine ► Chlorambucil for low grade tumors Canine MCTs ► Treatment ► Systemic therapy MroSIM He - ► Palladia > - Blocks Drigina Signites ► Designed for treatment of canine MCTs due to presence of c-Kit mutations ►Consider using in cases with known c-Kit mutation (from prognostic panel)? ►Good choice for many owners since it is given at home Dal Toxicity ?? Canine MCTs ► Treatment ► Systemic therapy ► Gilvetmab ► New therapy ► Conditionally licensed for dogs with mast cell tumors (stage 1,2,3) ► Also for dogs with melanoma (stages 2,3) ► Immune checkpoint inhibitor ► Monoclonal antibody against PD-1 Canine MCTs ► Treatment ► Intratumoral injection ► Triamcinolone ► Many MCTs appear larger due to degranulation ► If tumor is “squishy”, this can be a good option - DECRANCATED Puffy , ► Stelfonta ► Inject directly into tumor ► Tumor sloughs off > - CASTIC Alt ► Supposed to have controlled healing ► Sometimes serious wounds ► Varying opinions on its use! Feline MCTs - Cutaneous ► The majority of cutaneous mast cell tumors in cats are benign Aus - MULTIPLE D ► Surgery is treatment of choice b ► No established histologic grading system ► Well-differentiated vs. anaplastic ► May have prognostics significance https://journals.sagepub.com/doi/full/10.1177/1098612X12470343 ► Chemotherapy/Palladia if anaplastic ► Evaluate for other cutaneous tumors ► Staging with abdominal ultrasound +/- thoracic radiographs ► Multiple cutaneous mast cell tumors ► Chemotherapy/Palladia Feline MCTs -Visceral ► Splenic ↓ Visceral Form D ► Most common differential for splenic disease in cats ► Most cats do not have concurrent cutaneous involvement ► Most cats have other organ involvement ► Liver, LNs, bone marrow, blood etc. ► Treatment ► Surgery, even in the face of disseminated disease ► Median survival times 1-1.5 years ► Chemotherapy/Palladia post-surgery Feline MCTs -Visceral ► Gastrointestinal mast cell tumor ► Prognosis is generally considered poor due to high metastatic rate at the time of diagnosis ► One study of intestinal sclerosing mast cell tumor found a greater than 80% metastatic rate with survival times around 2 months. ► More recent study found median survival time of 1.5 years ► Treatment ► Surgery, if no disseminated metastasis, plus adjuvant post-op chemotherapy/targeted therapy. ► If disseminated disease then chemotherapy/Palladia Time for a break…