AML with Multilineage Dysplasia (MLD) Correlates with MDS-Related Cytogenetic Abnormalities and a Prior History of MDS or MDS/MPN but Has No Independent Prognostic Relevance: A Comparison of 461 Cases Classified as “AML Not Otherwise specified” or “AML with Myelodysplasia-Related changes” as Defined by the 2008 WHO Classification.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 823-823
Author(s):  
Miriam Miesner ◽  
Tamara Weiss ◽  
Katja Macijewski ◽  
Ulrike Bacher ◽  
Susanne Schnittger ◽  
...  
Keyword(s):  
Who Classification ◽  
Clinical Impact ◽  
Prior History ◽  
Prognostic Parameters ◽  
Cytogenetic Abnormalities ◽  
Multilineage Dysplasia ◽  
Not Otherwise Specified ◽  
History Of ◽  
Equity Ownership

Abstract Abstract 823 The new WHO classification of AML first considers genetic and molecular findings, the history of the patient but also stresses the importance of multilineage dysplasia (MLD) as independent parameter: Cases not classified as AML with recurrent genetic abnormalities or therapy-related AML are classified as AML with myelodysplasia-related changes (MRC) with one of the following parameters: AML after MDS or MDS/MPN (s-AML), AML with MDS-related cytogenetics and/or AML with MLD. All other cases are classified “AML, not otherwise specified” (NOS). We analyzed 1740 AML, 12.5% were AML with recurrent cytogenetic abnormalities, 7.4% were t-AML. We then evaluated a subgroup of 461 pts with AML without recurrent cytogenetic abnormalities. All of them were included based on complete availability of clinical data, cytogenetic and molecular features and adequate material for morphologic assessment. After morphologic analysis another 53 cases had to be excluded as dysplastic features were not evaluable following WHO guidelines. Following the WHO proposal cases of the provisional entities “AML with mutated NPM1” and “AML with mutated CEBPA” have not been excluded. We investigated dysplasia in all cases (n= 408) and found 184 AML with MRC (45.1%) and 224 AML NOS (54.9%). In 93/184 (50.5%) cases MLD alone led to the classification as AML with MRC. Out of the remaining 91 cases 42 had AML arising from previous MDS or MDS/MPN and 55 had AML with an MDS-related cytogenetic abnormality (both parameters present in 5 cases). Event-free survival (EFS) and overall survival were comparable in AML with and without MLD (median EFS 13.8 vs. 15.2 months, n.s.; median OS 24.5 vs. not reached, n.s.). MLD was positively correlated to the incidence of pre-existing MDS or MDS/MPN (frequency in cases with pre-existing MDS or MDS/MPN vs. others 66.7% vs. 33.1%, p<0.0001) and to MDS-related cytogenetic abnormalities (frequency in cases with MDS-related cytogenetic abnormalities vs. others 54.5% vs. 33.7%, p= 0.004). Thus, to analyze whether or not MLD as a sole criterion has clinical impact the following evaluations focused on the subgroup AML MLD sole (AML with MLD and without other MRC in comparison to AML NOS regarding clinical and prognostic parameters including age, WBC, cytogenetics, molecular markers, OS and EFS. Median age was 61.7 vs. 66.0 years in AML MLD vs. AML NOS (range 20.4-85.0 vs. 18.3-88.1 years, p=0.027) and the median WBC count was 18.3 vs. 13.4 G/l (range 0.4-370.0 vs. 0.14-600.0 G/L, n.s.). Pts with AML MLD exhibited a slightly lower frequency of NPM1 mutations (58.0% vs. 64.7%, n.s.) and a lower frequency of FLT3-ITD (18.0% vs. 28.5%, p= 0.061), and showed slightly more frequently NRAS mutations (18.2% vs. 9.6%, n.s.). Frequencies of MLL-PTD and CEBPA-mutations were similar between both groups. In the subgroup AML MLD sole (AML with MLD and without other MRC) in comparison to AML NOS, the presence of MLD has no impact on EFS (median 17.5 vs. 16.0 months, n.s.) and OS (3-year-OS 54.8% vs. 53.9%, n.s.). Further analyses were performed for the total cohort (n=408). MDS-related cytogenetics was associated with shorter EFS (median 7.2 vs. 15.2 months, p=0.011) and OS (median 17.4 months vs. not reached, p=0.010). Also, s-AML was associated with shorter EFS (12.7 vs. 15.6 months, p=0.099) and OS (15.0 months vs. not reached, p=0.027). Furthermore we assessed the prognosis of pts with AML NOS combined with the subgroup of AML MRC showing MLD only (n= 317) vs. all other cases with AML MRC being assigned to this group based on cytogenetics or preceding MDS/MPN (n= 91). A significant difference in OS (AML NOS and AML MLD only vs. AML MRC based on cytogenetics or preceding MDS/MPN, median OS not reached vs. 15.8 months, p= 0.001) and EFS (median 16.8 vs. 10.2 months, p= 0.004) was seen. Among the other prognostic parameters, only absence of NPM1 mutation, presence of MLL-PTD and higher age were significantly associated with a worse EFS and OS. In multivariate analysis a higher age was the only parameter independently related to worse EFS (p<0.0001), and higher age (p<0.0001) and MLL-PTD (p=0.033) were the only parameters independently related to shorter OS. These facts lead to the conclusion that MLD alone has very limited clinical impact and that pts with MLD and without previous MDS or MDS/MPN or MDS-related cytogenetic abnormalities should not be classified only by morphology as AML MRC. We suggest that classification of pts with AML could be simplified by only using cytogenetics and prior history for a reproducible risk-stratification in the setting of clinical trials. Disclosures: Miesner: MLL Munich Leukemia Laboratory: Employment. Weiss:MLL Munich Leukemia Laboratory: Employment. Macijewski:MLL Munich Leukemia Laboratory: Employment. Schnittger:MLL Munich Leukemia Laboratory: Equity Ownership. Haferlach:MLL Munich Leukemia Laboratory: Equity Ownership. Kern:MLL Munich Leukemia Laboratory: Equity Ownership. Haferlach:MLL Munich Leukemia Laboratory: Equity Ownership.

Multilineage dysplasia (MLD) in acute myeloid leukemia (AML) correlates with MDS-related cytogenetic abnormalities and a prior history of MDS or MDS/MPN but has no independent prognostic relevance: a comparison of 408 cases classified as “AML not otherwise specified” (AML-NOS) or “AML with myelodysplasia-related changes” (AML-MRC)

Blood ◽  
2010 ◽  
Vol 116 (15) ◽  
pp. 2742-2751 ◽  
Author(s):  
Miriam Miesner ◽  
Claudia Haferlach ◽  
Ulrike Bacher ◽  
Tamara Weiss ◽  
Katja Macijewski ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Myeloproliferative Neoplasm ◽  
World Health ◽  
Prior History ◽  
Multilineage Dysplasia ◽  
Not Otherwise Specified ◽  
History Of ◽  
Health Organization ◽  
Acute Myeloid

Abstract The World Health Organization classification of acute myeloid leukemia (AML) is hierarchically structured and integrates genetics, data on patients' history, and multilineage dysplasia (MLD). The category “AML with myelodysplastic syndrome (MDS)–related changes” (AML-MRC) is separated from “AML not otherwise specified” (AML-NOS) by presence of MLD, MDS-related cytogenetics, or history of MDS or MDS/myeloproliferative neoplasm (MPN). We analyzed 408 adult patients categorized as AML-MRC or AML-NOS. Three-year event-free survival (EFS; median, 13.8 vs 16.0 months) and 3-year overall survival (OS; 45.8% vs 53.9%) did not differ significantly between patients with MLD versus without. However, MLD correlated with preexisting MDS (P < .001) and MDS-related cytogenetics (P = .035). Patients with MLD as sole AML-MRC criterion (AML-MLD-sole; n = 90) had less frequently FLT3 internal tandem duplication (P = .032) and lower median age than AML-NOS (n = 232). Contrarily, patients with AML-NOS combined with AML-MLD-sole (n = 323) had better 3-year EFS (16.9 vs 10.7 months; P = .005) and 3-year OS (55.8% vs 32.5%; P = .001) than patients with history of MDS or MDS/MPN or MDS-related cytogenetics (n = 85). Gene expression analysis showed distinct clusters for AML-MLD-sole combined with AML-NOS versus AML with MDS-related cytogenetics or MDS history. Thus, MLD alone showed no independent clinical effect, whereas cytogenetics and MDS history were prognostically relevant.

scholarly journals MTE11.01 The Clinical Impact of the 2015 WHO Classification of Lung Tumors

2017 ◽  
Vol 12 (1) ◽  
pp. S160-S162
Author(s):  
Andrew Nicholson ◽  
Masayuki Noguchi
Keyword(s):  
Who Classification ◽  
Lung Tumors ◽  
Clinical Impact

Analysis of Second Primary Malignancies in Lenalidomide-Treated Patients with IPSS Low- or Int-1-Risk Myelodysplastic Syndromes

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1704-1704 ◽  
Author(s):  
Aristoteles Giagounidis ◽  
Azra Raza ◽  
Alan F. List ◽  
Pierre Fenaux ◽  
Bouchra Benettaib ◽  
...  
Keyword(s):  
Research Funding ◽  
Prior History ◽  
Second Primary ◽  
Employment Equity ◽  
Phase 3 ◽  
Advisory Committees ◽  
Increased Risk ◽  
History Of ◽  
Equity Ownership ◽  
Rbc Transfusion

Abstract Abstract 1704 Background: Lenalidomide (LEN) is approved in the US for the treatment of RBC transfusion-dependent patients with IPSS Low- or Int-1-risk myelodysplastic syndromes (MDS) with del(5q), with or without other cytogenetic abnormalities. In a phase 3 trial, treatment with LEN 5 mg and 10 mg resulted in RBC transfusion independence (TI) for ≥ 26 weeks in 43% and 56% of such patients, cytogenetic response in 25% and 50%, and a significant improvement of health-related quality of life (p <.05 for both 5 mg and 10 mg). Achievement of RBC-TI ≥ 8 weeks was associated with a significantly reduced risk of AML progression and death (p <.05 for both) (Fenaux P et al. Blood 2011;doi: 10.1182/blood-2011-01-330126). In newly diagnosed multiple myeloma patients, results of phase 3 trials showed a numerical imbalance in the occurrence of second primary malignancies (SPMs) between patients treated with LEN (in combination with melphalan or immediately after high-dose melphalan therapy and stem cell transplantation) and control cohorts. SPMs were analyzed in clinical trials of LEN across indications, including MDS. Methods: This was a single arm analysis of SPM data retrieved from RBC transfusion-dependent patients with IPSS Low- or Int-1-risk MDS with or without del(5q) who received LEN as monotherapy in 5 studies (MDS-001, -002, -003, -004, and -007). The cutoff date was February 28, 2011. SPMs were defined using MedDRA (Medical Dictionary for Regulatory Activities) categories of invasive SPMs (hematologic malignancies and solid tumors) and non-melanoma skin cancers (NMSC). Acute myeloid leukemia (AML) is considered part of the natural history of disease progression in MDS. Although further follow-up is needed, results of a phase 3 study showed no obvious evidence for an increased risk of AML progression in LEN-treated RBC transfusion-dependent patients with IPSS Low- or Int-1-risk MDS and del(5q) (Fenaux P et al. Blood 2011;doi: 10.1182/blood-2011-01-330126). AML was not included in the present analysis. The overall number of SPMs (invasive malignancies and NMSC), and the number and incidence rate (IR) of all invasive SPMs were evaluated, with IR defined as the number of new events per 100 person-years (pys). The IR of invasive SPMs was compared with the IR of new events of invasive cancer as reported from the SEER (Surveillance, Epidemiology, and End Results) cancer registry (2.1/100 pys for persons aged ≥ 65 years) (Howalder N et al. National Cancer Institute, 2011). Results: The combined population of all 5 studies comprised 557 LEN-treated patients. The median age was 71 years (range 27–95 years) and 72% of patients were aged ≥ 65 years. 88 patients (15.8%) had a prior history of cancer including malignant melanoma, meningioma, breast cancer, lung cancer, squamous cell carcinoma, and basal cell carcinoma. A total of 28 patients (5.0%) developed ≥ 1 SPM, including 17 (3.1%) with an invasive SPM and 12 (2.2%) with NMSC; 1 patient had both an invasive malignancy and a NMSC. Two of the 17 patients with invasive SPMs had a B-cell malignancy and 15 had solid tumors of heterogeneous type. Of the 28 patients with SPMs in total, 5 patients had a prior history of cancer. The IR of invasive SPMs was 2.60/100 pys (95% confidence interval 1.56–4.07), which is consistent with the IR reported in the SEER database among patients in this age group (2.1/100 pys for persons aged ≥ 65 years). The median time to onset of SPMs was 13.5 months (range 0.3–48.6 months). Conclusion: There was no clear evidence to associate LEN treatment with an increased risk of developing SPMs in patients with Low- or Int-1-risk MDS with or without del(5q). The IR of invasive SPMs among these LEN-treated patients is what would be expected from population-based estimates of invasive cancer incidence among persons in this age group. The collection of data on SPMs in LEN-treated patients including post-marketing information is ongoing. Disclosures: Giagounidis: Celgene Corporation: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. List:Celgene Corporation: Consultancy, Honoraria, Research Funding. Fenaux:Merck: Honoraria; Johnson & Johnson: Honoraria; Amgen: Honoraria, Research Funding; Roche: Honoraria, Research Funding; Celgene Corporation: Honoraria, Research Funding; Cephalon: Honoraria; Novartis: Honoraria. Benettaib:Celgene Corporation: Employment, Equity Ownership. Brown:Celgene Corporation: Employment, Equity Ownership. Zhong:Celgene Corporation: Employment, Equity Ownership. Brandenburg:Celgene Corporation: Employment, Equity Ownership. Mufti:Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Clinical characterization of acute myeloid leukemia with myelodysplasia-related changes as defined by the 2008 WHO classification system

Blood ◽  
2009 ◽  
Vol 113 (9) ◽  
pp. 1906-1908 ◽  
Author(s):  
Olga K. Weinberg ◽  
Mahesh Seetharam ◽  
Li Ren ◽  
Katie Seo ◽  
Lisa Ma ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Who Classification ◽  
Progression Free Survival ◽  
World Health ◽  
Multilineage Dysplasia ◽  
Molecular Features ◽  
Not Otherwise Specified ◽  
Cebpa Mutations ◽  
Acute Myeloid

Although some studies have validated the 2001 World Health Organization (WHO) classification of acute myeloid leukemia (AML), including the importance of multilineage dysplasia, others have suggested that multilineage dysplasia correlates with unfavorable cytogenetics but has no independent impact on prognosis. In 2008, the revised WHO classification has expanded this category into “AML with myelodysplasia-related changes” (AML-MRC). We evaluated the clinical, pathologic, cytogenetic, and molecular features of 100 AML patients using the 2008 WHO criteria. Patients underwent genetic screening for NPM1, FLT3-ITD, FLT3-D835, and CEBPA mutations. Compared with patients with AML, not otherwise specified, patients with AML-MRC were significantly older (P = .014), presented with a lower hemoglobin (P = .044), more frequently expressed CD14 (P = .048), and exhibited a decreased frequency of CEBPA mutations (P = .001). Multivariate analysis indicated that patients with AML-MRC had a significantly worse overall survival, progression-free survival, and complete response compared with AML-not otherwise specified (all P < .001). These data support the clinical, morphologic, and cytogenetic criteria for this 2008 WHO AML category.

Comprehensive Investigation of 225 Patients with Myeloid Malignancies and Erythroid Hyperplasia (≥50%) Demonstrates That Acute Erythroid Leukemia (AEL, according WHO Classification 2008) Differs Significantly From MDS but Overlaps with Other AML Subtypes and Pure AEL Regarding Clinical and Genetic Features.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1672-1672
Author(s):  
Ulrike Bacher ◽  
Claudia Haferlach ◽  
Tamara Alpermann ◽  
Susanne Schnittger ◽  
Wolfgang Kern ◽  
...  
Keyword(s):  
Who Classification ◽  
Molecular Genetic ◽  
Erythroid Cells ◽  
Employment Equity ◽  
Not Otherwise Specified ◽  
Erythroid Hyperplasia ◽  
Genetic Abnormalities ◽  
Genetic Features ◽  
Equity Ownership ◽  
Who 2008

Abstract Abstract 1672 Introduction: According to the WHO 2008, acute erythroid leukemia (AEL) is defined by erythroid hyperplasia ≥50% and ≥20% of myeloblasts of non-erythroid cells but <20% of all nucleated cells. “Pure AEL” is defined by ≥80% of erythropoiesis without relevant myeloblasts. Cases with erythroid hyperplasia ≥50% and ≥20% of myeloblasts of all nucleated cells are classified as acute myeloid leukemia (AML-MRC/NOS), while presence of <20% of myeloblasts of non-erythroid cells assigns cases to myelodysplastic syndrome (MDS). As the separation of MDS/AML with erythroid hyperplasia in different categories is still under debate, we studied 225 patients with MDS/AML and ≥50% erythroid cells in bone marrow (BM) for cytomorphology, cyto-/molecular genetics, and prognosis. Patients/Methods: The cohort consisted of 225 pts (f/78; m/147; median age, 68.8 yrs; 18.5–88.4 yrs) with BM erythroid hyperplasia (≥50%) and different myeloid subtypes strictly defined according to WHO 2008: MDS: n=107; AML-MRC/NOS: n=32; AEL: n=79, pure AEL: n=7 (the WHO cohort “AML with recurrent genetic abnormalities” was excluded). All pts were investigated by MGG staining of BM and chromosome banding/FISH. In addition, we performed analysis for the NPM1 mutations (n=126 investigated), FLT3-ITD (n=135), MLL-PTD (n=136), and NRAS mutations (n=90). Results: MDS subtypes were as follows: RA: n=18; RARS: n=18; RCMD: n=21; RCMD-RS (WHO 2001): n=26; RAEB-1: n=22; RAEB-2: n=2. Most AML pts were categorized as “AML with myelodysplasia related changes; AML-MRC” (27/30 cases; 90%); 3 pts were classified as “AML, not otherwise specified; AML-NOS”, 2 pts were not evaluable for this aspect. We first compared the MDS cohort (n=107) with the AML cohort (all 118 pts with AML-MRC/NOS, AEL, and pure AEL): Overall survival (OS) was better in MDS than in the AML cohort (median: not reached vs. 13.9 months; p<0.001). In contrast, OS showed no significant differences across the AML-NOS/MRC, AEL, and pure AEL subgroups (9.3 vs. 13.9 vs. 6.1 months; n.s.). In the total cohort, aberrant karyotypes (KTs) were detected in 105/225 pts (46.7%) and were associated with inferior median OS when compared to normal KTs (aberrant KTs: 12.5 months vs. normal KTs: not reached; p<0.001). Aberrant KTs were more frequent in the AML categories when compared to MDS (69/118; 58.5%; vs. 36/107; 33.6%; p<0.001), but showed no significant differences across the different AML subgroups: AML-MRC/NOS: 20/32; 62.5%; AEL: 44/79; 55.7%; pure AEL: 5/7; 71.4%; n.s.). Performing cytogenetic risk categorization according to revised MRC criteria (Grimwade, 2010) for the whole cohort, unfavorable KTs showed an inferior prognosis compared to intermediate KTs (unfav. KTs: 65/225; 28.9%; median OS: 7.6 months; vs. intermed. KTs: 160/225; 71.1%; not reached; p<0.001). The pts from the AML cohort more frequently had unfav. KTs than those with MDS (AML cohort: 50/118; 42.4% vs. MDS: 15/107; 14.0%; p<0.001). Unfav. KTs were similarly distributed in the AML cohort (AML-MRC/NOS: 14/32; 43.8%; AEL: 32/79; 40.5%; pure AEL: 4/7; 57.1). Regarding the molecular markers, we detected the NPM1mut in 25/126 investigated (19.8%; MDS: 0/43; AML cohort: 22/91; 24.2%), FLT3-ITD in 5/135 (3.7%; MDS: 0/43; AML cohort: 5/92; 5.4%), MLL-PTD in 12/136 (8.8%; MDS: 2/44; 4.5%; AML: 10/92; 10.9%), and NRASmut in 4/90 (4.4%; MDS: 1/42; 2.4%; AML: 3/48; 6.2%). Mutation frequencies did not differ significantly in the MDS vs. AML categories or across the AML-MRC/NOS, AEL, and pure AEL subgroups. Conclusions: MDS with erythroid hyperplasia (≥50%) was clearly separated from the AML cohort (consisting of AML-MRC/NOS, AEL, and pure AEL, all with ≥50% of erythropoiesis) by less adverse cytogenetics and by improved survival. In contrast, no significant differences were observed across the different acute leukemia subentities regarding prognosis and cyto-/molecular genetic features. These data support the separation of MDS and AML with ≥50% of erythroid precursors according to the WHO classification. However, with respect to different AML subgroups, the separation to AEL, pure AEL, and AML-MRC/-NOS having ≥50% erythropoiesis seems arbitrary: these AML subtypes show no significant differences regarding prognosis or genetic risk profiles. This argues in favor of a combined group of AML with erythroid hyperplasia aiming to facilitate the definition for clinical studies and the development of therapeutic strategies. Disclosures: Haferlach: MLL Munich Leukemia Laboratory: Employment, Equity Ownership, Research Funding. Schnittger:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Kern:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership.

The WHO classification of MDS does make a difference

Blood ◽  
2004 ◽  
Vol 103 (9) ◽  
pp. 3265-3270 ◽  
Author(s):  
Robert B. Howe ◽  
Anna Porwit-MacDonald ◽  
Robert Wanat ◽  
Ramin Tehranchi ◽  
Eva Hellström-Lindberg
Keyword(s):  
Median Survival ◽  
Who Classification ◽  
Therapeutic Response ◽  
World Health ◽  
Refractory Anemia ◽  
Ringed Sideroblasts ◽  
Additional Information ◽  
Multilineage Dysplasia ◽  
Health Organization

Abstract The purpose of this study was to determine the facility and reliability of the World Health Organization (WHO) classification of myelodysplastic syndromes (MDSs) with several observers reviewing the same diagnostic specimens. We also wanted to determine if the WHO classification provided additional information about predictability of clinical response outcome. To accomplish these goals we reviewed 103 previously diagnosed cases of low-risk MDS. We found 92% interobserver agreement (P &lt; .001). Sixty-four of these patients had been entered into clinical trials using growth factors by the Nordic MDS Study Group. The WHO classification reliably predicted therapeutic response to the combination of granulocyte colony-stimulating factor (G-CSF) and erythropoietin (Epo). The response rate differed significantly between refractory anemia with ringed sideroblasts (RARS) and refractory anemia with multilineage dysplasia and ringed sideroblasts (RCMD/RS) with regard to therapeutic response (75% versus 9%; P = .003). Also, in the group of patients with less than 5% marrow blasts, there was a difference in median survival between patients with unilineage dysplasia (51% surviving at 67 months) and those with multilineage dysplasia (median survival, 28.5 months; P = .03). (Blood. 2004;103:3265-3270)

scholarly journals Epithelial lacrimal gland tumors in dogs and cats: Is the human WHO classification appropriate for animals?

2021 ◽  
pp. 030098582110257
Author(s):  
Chiara Giudice ◽  
Laura Nordio ◽  
Micol Cadonici ◽  
Maria Novella Perelli ◽  
Mario Caniatti
Keyword(s):  
Lacrimal Gland ◽  
Who Classification ◽  
Classification Scheme ◽  
World Health ◽  
Myoepithelial Carcinoma ◽  
Not Otherwise Specified ◽  
Uncommon Case ◽  
Epithelial Myoepithelial Carcinoma ◽  
Health Organization

Lacrimal gland tumors (LGTs) in dogs and cats are rare neoplasms that can affect either the nictitans (NLG) or the main lacrimal gland (MLG). A consistent classification scheme for canine and feline LGTs is lacking; however, the importance of a classification scheme for LGTs has been emphasized in the human literature, and an update to the World Health Organization (WHO) classification has recently been published. The aim of this study was to investigate the occurrence of different subtypes of canine and feline LGTs in accordance with the human WHO classification system. Epithelial LGTs ( n = 46 tumors; 38 dogs, 8 cats) were reviewed and immunophenotyping for p63, CK14, SMA, calponin, CKAE1/AE3, and CK19 was performed. Consistent with previous literature reports, lacrimal carcinomas outnumbered adenomas in dogs and cats. Based on the WHO classification of human LGTs, the most common subtypes identified in dogs were pleomorphic, ductal, adenoid cystic, and epithelial-myoepithelial carcinoma. In cats, a lower number of subtypes was observed, and adenocarcinoma “not otherwise specified” (NOS) was the most frequent diagnosis. An uncommon case of feline epithelial-myoepithelial carcinoma was also observed. The application of the human WHO-LGT classification scheme to canine and feline tumors increased the diversity of diagnoses and allowed for the identification of numerous subtypes. Further studies to identify possible correlations between pathological subtypes and prognosis are warranted.

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