{"id":1514818,"date":"2024-04-15T09:33:48","date_gmt":"2024-04-15T07:33:48","guid":{"rendered":"https:\/\/laboklin.com\/?p=1514818"},"modified":"2025-07-24T12:04:20","modified_gmt":"2025-07-24T10:04:20","slug":"the-diagnostic-work-up-of-mast-cell-tumours-in-dogs-and-cats","status":"publish","type":"post","link":"https:\/\/laboklin.com\/en\/the-diagnostic-work-up-of-mast-cell-tumours-in-dogs-and-cats\/","title":{"rendered":"The diagnostic work-up of mast cell tumours in dogs and cats"},"content":{"rendered":"

[vc_row][vc_column width=”2\/3″][vc_column_text css=””]The gold standard in the diagnosis of mast cell tumours (MCT) is cytology and histopathology. Clinical staging <\/strong>is based on the clinical picture including the lymph node status (cytological\/ histological). Immunohistological and molecular genetic methods are also available for more precise characterisation.<\/p>\n

Cytology <\/strong>is used for preoperative diagnosis (Fig. 1) and clinical staging (e.g. lymph nodes, spleen). Although cytological grading of canine mast cell tumours has been published (Blackwood et al. 2012), it has limitations, as the cytological malignancy criteria are often overestimated with subcutaneous MCT not being identified.<\/p>\n

Histopathology <\/strong>can be used to distinguish cutaneous from subcutaneous mast cells and assess the resection margins. Histological grading <\/strong>enables a statement to be made regarding the biological behaviour (probability of recurrence, risk of metastasis, survival times) of cutaneous mast cell tumours in dogs.<\/p>\n

There are two histopathological grading systems <\/strong>for cutaneous mast cell tumours <\/em>in dogs: The older grading system according to Patnaik et al. (1984) distinguishes between three tumour grades (grade I well differentiated – Fig. 2 -, grade II moderately differentiated and grade III poorly differentiated). It is based on the following criteria, among others: tumour loca- lisation, cell morphology, nuclear morphology, overall architecture and number of mitoses. As this system contains several criteria that are not easy to objectify, a modified two-stage system was established that is based on parameters that are easier to measure (Kiupel et al. 2011). In accordance with the recommendations of the consensus group (Berlato et al. 2021), a combination of both grading systems is currently usually specified, which correlate with prognostic statements (see Table 1) (Stefanello et al. 2015).<\/p>\n

If a mast cell tumour is subcutaneous<\/em>, the grading systems according to Patnaik et al. (1984) and Kiupel et al. (2011) should not be used, as subcutaneous MCTs are generally less malignant than cutaneous MCTs (Bellamy and Berlato 2022). With a few exceptions, they can generally be well controlled locally and usually require no further treatment once they have been completely removed (Betz 2021).<\/p>\n

Table 1: <\/strong>Prognostic statements for cutaneous mast cell tumours in dogs, based on the combined grading systems of Patnaik et al. (1984) and Kiupel et al. (2011) – modified according to Stefanello et al. (2015)<\/p>\n\n\n\n\n\n\n\n
Grading<\/strong><\/td>\nPrognosis<\/strong><\/td>\nTumour-related<\/strong> deaths<\/strong><\/td>\nRisk of lymph node metastases<\/strong><\/td>\nRisk<\/strong> for<\/strong> distant <\/strong>metastases<\/strong><\/td>\n<\/tr>\n
Grade I \/ low-grade<\/em><\/td>\ngood<\/td>\nrare<\/td>\n6 %<\/td>\n2 %<\/td>\n<\/tr>\n
Grade II \/ low-grade<\/em><\/td>\nmostly good<\/td>\n3 % to 17 % of dogs die as a result of the mast cell tumour.<\/td>\n16 %<\/td>\n2 %<\/td>\n<\/tr>\n
Grade II \/ high- grade<\/em><\/td>\ncautious<\/td>\n14% to 56% of dogs die as a result of the mast cell tumour.<\/p>\n

Median survival time: 7.5 to 23.3 months<\/td>\n

15 %<\/td>\n2 %<\/td>\n<\/tr>\n
Grade III \/ high- grade<\/em><\/td>\nvery cautious to unfavourable<\/td>\n67 to 75 % of dogs die as a result of the mast cell tumour.<\/p>\n

Median survival time: 3.6 to 6.8 months<\/td>\n

46 %<\/td>\n21 %<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

Furthermore, lymph nodes <\/strong>can be examined histologically for a neoplastic tumour cell population. The assessment is based on the scheme by Weishaar et al. (2014). The prognosis is significantly better in stages HN0\/HN1 than in HN2\/HN3.<\/p>\n

HN0: None to isolated (0-3 mast cells\/HPF), scattered and solitary mast cells in the sinus (subcapsular, paracortical or medullary) and\/or in the parenchyma. Assessment: no metastatic infiltration (reactive or normal).<\/p>\n

HN1: More than 3 scattered and solitary mast cells in the sinus (subcapsular, paracortical or medullary) and\/or parenchyma in at least 4 HPF. Assessment: pre-metastatic (grey area).[\/vc_column_text][\/vc_column][vc_column width=”1\/3″][vc_column_text css=””]<\/p>\n\n\t\t\t