Histologic grade has a higher‐weighted value than nodal status as predictor of outcome in dogs with cutaneous mast cell tumours and overtly metastatic sentinel lymph nodes

Abstract

In canine cutaneous mast cell tumours (cMCTs), histologic grade and clinical stage are the most important prognostic factors, with high‐grade tumours and metastatic lymph nodes (LNs) significantly influencing the evolution of disease. However, it is uncertain whether histologic grade and clinical stage should be given equal weighting value in patient prognostication and management. Dogs with low‐ and high‐grade cMCTs and at least one overtly metastatic sentinel LN undergoing standardized treatment, consisting of surgical excision of the cMCT, lymphadenectomy and chemotherapy, were retrospectively included. The aim was to determine whether, at the same clinical stage, histologic grade retained prognostic relevance. Sixty dogs were included: 26 had a high‐grade cMCT tumour and 34 had a low‐grade cMCT. Median follow‐up was 367 days (range, 187–748) in the high‐grade group, and 1208 days (range, 180–2576) in the low‐grade group. Median time to progression was significantly shorter in the high‐grade group than in the low‐grade group (214 days versus not reached; p < .001), as well as tumour‐specific survival (545 days versus not reached; p < .001). On multivariable analysis, a high histologic grade and incomplete margins retained prognostic significance for both tumour progression and tumour‐specific death. In dogs with cMCT and at least one overtly metastatic LN undergoing multimodal treatment, histologic grade significantly correlated with outcome. Overall prognosis was not unfavourable, even in the high‐grade group, further supporting that a multimodal therapeutic approach, addressing primary tumour and sentinel LN, should be offered. Whether chemotherapy should be incorporated in the therapeutic planning of low‐grade cMCTs remains to be defined.

Subcutaneous mast cell tumours: A prospective multi‐institutional clinicopathological and prognostic study of 43 dogs

“…However, all dogs underwent wide surgical excision of the primary tumour and had their regional LNs removed, and 35% of the dogs also received medical treatment based on the presence of overt nodal metastatic disease. It is not known whether medical therapy made a difference and was really indispensable; however, based on what has been published on cutaneous MCTs, 24,11,27 we believe that dogs with HN3 LNs require a multimodal treatment. This is also supported by the fact that all five dogs that died of MCT-related causes had at least one HN3 LN at admission, highlighting that, albeit rarely, even the subcutaneous localisation can have a fatal outcome.…”

“…In the case of infiltrated margins, dogs had to undergo scar re‐excision and were ultimately enrolled only upon the histological confirmation of adequately locally controlled ScMCT. In the presence of overt (histological node 3, HN3) 10 nodal metastasis, dogs received adjuvant vinblastine, as later detailed, in accordance with previous literature focusing on cutaneous MCTs 11,12 . The remaining dogs were monitored.…”

“…In the presence of overt (histological node 3, HN3) 10 nodal metastasis, dogs received adjuvant vinblastine, as later detailed, in accordance with previous literature focusing on cutaneous MCTs. 11,12 The remaining dogs were monitored.…”

Evaluation of Tumor Grade and Proliferation Indices before and after Short-Course Anti-Inflammatory Prednisone Therapy in Canine Cutaneous Mast Cell Tumors: A Pilot Study

“…The prognosis and subsequent management of the patient after definitive local therapy is dichotomized by the MCT grade. Typically, low-grade tumors require no further treatment, even if incompletely excised, and patients are expected to have good to excellent outcomes, while patients with high-grade tumors are expected to succumb to their disease and require intensive multi-modal therapeutic strategies [1,2,6,[35][36][37][38][39]48,[52][53][54][59][60][61][62][63][64][65][66][67]. This then raises the question of how preoperative glucocorticoid treatment may impact the histological parameters and criteria for grade determination and the immunohistochemical detection of proliferation indices in canine MCTs.…”

Evaluation of Tumor Grade and Proliferation Indices before and after Short-Course Anti-Inflammatory Prednisone Therapy in Canine Cutaneous Mast Cell Tumors

“…The prognosis and subsequent management of the patient after definitive local therapy is dichotomized by MCT grade. Typically, low-grade tumors require no further treatment, even if incompletely-excised, and patients are expected to have good to excellent outcomes; while patients with high-grade tumors are expected to succumb to their disease and require intensive multi-modal therapeutic strategies [1,2,6,[35][36][37][38][39]48,52,55,[60][61][62][63][64][65][66][67][68][69]. This then raises the question of how pre-operative glucocorticoid treatment may impact histological parameters, criteria for grade determination and immunohistochemical detection of proliferation indices in canine MCTs.…”