Small intestinal peripheral nerve sheath tumour in a cat

A rare case of cecal malignant peripheral nerve sheath tumor in a dog

A 12-year-old mixed-breed dog presented with a 2-month history of abdominal distension. Radiographic examination, abdominal ultrasonography, and computed tomography revealed a mass in the cecum (15.0 × 11.9 × 4.5 cm). The cecal mass was surgically removed and examined histopathologically. Immunohistochemically, the neoplastic cells expressed S-100 and neuron specific enolase but not α-smooth muscle actin and CD117 (c-kit). These histologic and immunohistochemical features indicated that the mass was consistent with a malignant peripheral nerve sheath tumor (MPNST). In dogs, most MPNSTs arise from the brachial plexus, spinal nerve root, and skin of the extremities. However, gastrointestinal MPNSTs in dogs have not been described previously. To the best of our knowledge, this is the first report to describe cecal MPNST in a dog.

Spindle cell sarcomas, suggestive of peripheral nerve sheath tumours, arising in the tongues of two cats

Case summary

Two domestic shorthair cats, one an 11-year-old female neutered cat and the other a 13-year-old male neutered cat, presented with partly raised, well-demarcated masses at the rostral tip of the tongue. Histological examination and immunohistochemical staining were consistent with sarcomas, and were most suggestive of peripheral nerve sheath tumours. One tumour had histological features consistent with a malignant peripheral nerve sheath tumour (PNST).

Relevance and novel information

Feline PNSTs arising on the tongue are rarely described in the published literature, and, to our knowledge, a case of malignant PNST originating at this site has not been described to date. Therefore, this represents a new differential diagnosis for cats presenting with a lingual mass. Regardless of histological malignancy, in cats these tumours have the potential for local recurrence but appear very unlikely to metastasise.

Colonic malignant peripheral nerve sheath tumour in a cat

Case summary

A 14-year-old male neutered domestic mediumhair cat presented with a 4 month history of inappetence and weight loss. Pertinent abnormalities on haematology and biochemistry included a mild microcytic regenerative anaemia (packed cell volume [PCV] 24% [reference interval (RI) 30–45%], mean cell volume 30.8 fl [RI 40–45 fl], absolute reticulocyte count 326.8 × 10¹²) and increased alkaline phosphatase activity (76 IU/l; RI <50 IU/l). Abdominal ultrasound and CT scan revealed masses in the transverse colon (2.0 cm × 1.2 cm) and right medial liver lobe (5.0 cm diameter). Thoracic radiographs were unremarkable. Right medial liver lobe resection and colectomy were performed. Immunohistochemistry was positive for S-100 protein, vimentin and glial fibrillary acidic protein, very weakly positive for c-kit and negative for muscle-specific actin and CD18, consistent with a colonic malignant peripheral nerve sheath tumour (MPNST) with a hepatic metastasis. Postoperative treatment with metronomic cyclophosphamide was well tolerated. Eighteen months postoperatively the cat re-presented after 3 days of progressive lethargy and inappetence. Haematology revealed a marked non- or pre-regenerative anaemia (PCV 10%). Coagulation times were prolonged (prothrombin time 39 s [RI 15–22 s] and activated partial thromboplastin time >300 s [RI 65–119 s]). Abdominal ultrasound identified multiple renal and hepatic nodules. Euthanasia was performed and post-mortem examination confirmed metastasis of the MPNST.

Relevance and novel information

This report describes the treatment of a metastatic colonic peripheral nerve sheath tumour in a cat. Feline visceral MPNSTs are rare and little is known about prognosis or optimal treatment.