Clinical and immunohistochemical findings of splenic mast cell tumour in a cat: A case report

A 6-year-old, spayed, female, domestic shorthair cat presented with a 4-month history of chronic intermittent vomiting and anorexia. The haematologic results indicated moderate anaemia and a circulating mast cell population. The abdominal radiography revealed a markedly enlarged spleen. The cytological analysis of the spleen showed a uniform population of mast cells, and a diagnosis of systemic mastocytosis (splenic mast cell tumour with mastocytaemia) was made. This diagnosis was subsequently confirmed by the histopathological examination of the spleen. The immunohistochemistry for KIT showed KIT pattern II (focal cytoplasmic expression). A splenectomy and chemotherapy with vinblastine and prednisolone resulted in remission of the anaemia and other clinical signs. This case report highlights the importance of cytological evaluations of peripheral blood smears and/or aspirates of enlarged spleens for diagnosing splenic mast cell tumours and for quickly initiating the appropriate treatment.

Episiectomy and partial vaginectomy with urethroplasty for excision of vulvar mast cell tumour in a female dog

This case report describes the surgical treatment of a grade II mast cell tumour in the vulvar region of a 4-year-old female Miniature Pinscher dog. The patient weighed 2 kg, and the tumour measured 2 cm in diameter. The surgery involved an episiotomy, a partial vaginectomy, and a subsequent urethroplasty. Due to the patient’s small size, the surgical margins were set at 2 cm laterally and 2 cm deep, which meant that the entire vulva, as well as the ventral part of the vaginal canal had to be removed. Afterwards, the urethral ostium was elliptically fixed to the skin at the end of the urethroplasty. The follow-up evaluations revealed an excellent recovery without metastasis or recurrence over the following two years.

Collision tumour of two nodal metastases (adenocarcinoma and mast cell tumour) in a dog

An 11-year-old female neutered Labrador retriever was referred for a large vulvar mast cell tumour that extended into the vagina. Abdominal ultrasound revealed an enlarged right medial iliac lymph node, and cytology of the node was consistent with an endocrine/neuroendocrine tumour. An approximately 1.5-cm right anal sac mass was palpated. Medial iliac lymphadenectomy via ventral celiotomy, right anal sacculectomy and marginal vulvar mass resection were performed. Histopathology was consistent with right anal sac adenocarcinoma, vulvar mast cell tumour, and the right medial iliac lymph node showed a metastatic collision of both the adenocarcinoma and mast cell tumour cell populations. Adjunctive chemotherapy and radiotherapy were recommended to address the risk of local recurrence and further metastasis but were declined by the owner. The dog remains alive and asymptomatic with no visible evidence of recurrence 14 months after initial presentation.

Metastatic mast cell tumour in African hedgehog: A case report

Neoplastic lesions are common in African hedgehogs (Atelerix albiventris). To our knowledge, so far mast cell tumour metastases have only been described in local lymph nodes. An African hedgehog was referred to the veterinary clinic. A nodule was located on the right part of the mandible. Based on the clinical trial, an abscess was suspected. Surgery was performed, but a histopathological examination was not undertaken. After few months, tumour recurrence was detected and, additionally, a second tumour was found on the metatarsal skin. Due to the deteriorating clinical condition of the patient, euthanasia was decided, and a post-mortem examination was performed. During the post-mortem examination, a spleen tumour was detected, and, furthermore, mesenteric lymph nodes, liver and lung sections were also collected. The histopathological examination confirmed mast cell tumour metastasis to the spleen and lymph nodes, additionally single mast cells were found in the liver. Interestingly, the histological picture of the tumour does not show high malignancy. To our knowledge, this is the first description of a mast cell tumour with metastases to the spleen and lymph in the African hedgehog.

Successful long-term management with toceranib phosphate of a recurrent muzzle mast cell tumour in a dog

A 10-year-old spayed female Yorkshire terrier with a muzzle mass was presented. The ulcerated mass was surgically resected, but recurred and grew rapidly over the subsequent 7 months. The submandibular lymph nodes were remarkably enlarged (right: 9.5 × 7.8 cm; left, 4.7 × 4.0 cm). The cytological analysis of the mass and lymph nodes revealed a high-risk mast cell tumour characterised by high mitotic figures (> 5/oil immersion field), nuclear pleomorphism, multi-nucleation, karyomegaly, and anisokaryosis. A polymerase chain reaction analysis targeting the c-kit domain revealed an exon 8 mutation. The resection of the mass was not considered optional because of the location. Oral toceranib (3.25 mg/kg, every other day) and prednisolone (1.0 mg/kg to 0.5 mg/kg, once a day) were administered, and the mass disappeared within 1 month. Subsequently, the toceranib therapy was stopped for 4 months due to neutropenia (0.7 × 10⁹/l). However, the mass recurred and the toceranib was resumed at the original dose, without affecting the neutropenia. No recurrence has been observed at the 16 months’ follow up. Despite the persistent neutropenia, no clinical symptoms have presented. This is another report of the successful treatment of a recurrent muzzle MCT with toceranib in a dog.