Surgical and medical management of an oral spindle cell sarcoma in an African hedgehog (Atelerix albiventris)

Abstract A 2.5‐year‐old male African hedgehog (Atelerix albiventris) presented with an intraoral, soft tissue mass overlying the left mandible. A computed tomography scan and subsequent fine needle aspirate suggested a malignant spindle cell tumour. The tumour was excised with a partial hemimandibulectomy. Histopathology demonstrated an incompletely excised spindle cell sarcoma. The hedgehog underwent adjuvant therapy consisting of intravenous carboplatin and oral lomustine, followed by palliative radiation therapy once tumour recurrence was noted on follow‐up surveillance. Radiation therapy was initially successful in decreasing tumour size, but the hedgehog re‐presented a month later acutely non‐ambulatory paraparetic with a distal right antebrachial mass. Diagnostics including radiographs and fine needle aspirate were consistent with metastatic neoplasia and humane euthanasia was elected.

the bleeding oral mass and the ingestion of blood (Table 1)   Despite initial improvement, about a month later the hedgehog became acutely non-ambulatory paraparetic. Upon re-evaluation, the tumour was larger and displacing the tongue laterally, there was a firm nodule on the lateral aspect of the right carpus, and the urinary bladder was large and firm. Under general anaesthesia blood and urine was collected, fine needle aspirate of the right carpal nodule was obtained and full body and right forelimb radiographs were performed. Radiographs showed variably sized lytic lesions within the proximal humeral metaphyses and humeral heads, body of T5, right ilium, left pubis and ribs ( Figure 4). A polyostotic osseous lesion with adjacent dorsolat-eral soft tissue swelling was noted within the right distal antebrachium ( Figure 5). Bloodwork revealed mild anaemia, hypercalcemia, and azotaemia most likely secondary to a paraneoplastic syndrome and postrenal azotaemia (Table 1). Urinalysis was normal. Cytology of the carpal nodule was consistent with a spindle cell neoplasm. Due to evidence of metastatic neoplasia and poor prognosis the hedgehog was humanely euthanized.
Despite successful surgical excision, tumour regrowth can occur. In this report, the spindle cell tumour was incompletely excised with a partial hemimandibulectomy. After regrowth, it was presumed to have metastasized to the thoracic vertebrae, causing spinal cord compression and consequent urinary bladder dysfunction and hindlimb paraparesis. There are other reports of sarcomas compressing or invading the central nervous system and causing neurological deficits in hedgehogs (Delgado et al., 2017;Ogihara et al., 2017;Peauroi et al., 1994).
Chemoradiotherapy (CR) is commonly used for tumour management in canines and felines (Rejec et al., 2015). To date, there are no established CR protocols for hedgehogs and methods are often extrapolated from canine and feline protocols. There are two separate reports of surgical excision and follow-up radiation therapy (RT) for management of a C-cell thyroid carcinoma in an African hedgehog and an amelanotic melanoma in a Lesser Madagascar Hedgehog Tenrec (Echinops telfairi) (LaRue et al., 2016;Harrison et al., 2010). There is also a single report of electrochemotherapy for management of an oral squa-mous cell carcinoma in a hedgehog with intralesional bleomycin and trains of biphasic electric pulses (Spugnini et al., 2018). In this report, the hedgehog was given intravenous carboplatin and oral lomustine, followed by RT once the tumour re-grew. CR was well tolerated and effective in decreasing tumour size in this hedgehog initially, but overall efficacy is uncertain as evidence of metastatic disease led to humane euthanasia.
CR in this report was challenging, primarily due to small patient size and lack of established protocols in hedgehogs. Vascular access was lost during a carboplatin treatment, forcing some of the dose extravascular. Additionally, vascular access could not be obtained during one visit, so the hedgehog needed to return the following week which prolonged therapy.
Detecting evidence of metastatic disease can also be difficult in hedgehogs as metastatic pulmonary nodules can be missed radiographically due to artifact of summating quills. It is important for the clinician to understand that a physical examination under general anaesthesia with complete blood count, serum biochemistry, urinalysis, thoracic radiographs, abdominal ultrasound and fine needle aspirate and cytology are necessary for complete neoplasia workup (Heatley et al., 2005).
This report illustrates that partial hemimandibulectomy and CR for a spindle cell sarcoma could improve long-term prognosis in a hedgehog.
Both treatment modalities were well-tolerated, but more studies are needed to establish efficacy and specific protocols for the hedgehog patient. This study also highlights the reality that more complete local tumour control, by achieving clear surgical margins initially, will afford better long-term outcome. If complete tumour excision is not possible and positive margins are found, adjuvant therapy consisting of immediate RT may result in better local tumour control and decrease risk of metastasis. Furthermore, following RT, re-biopsy of the area could have been performed to assess response to RT, much like is done with human patients (American Society for Therapeutic Radiology and Oncology Consensus Panel, 1999). If considering surgical and medical management, owners should be warned of tumour reoccurrence and the effect this has on survival and prognosis.

ETHICS STATEMENT
The authors confirm that the ethical policies of the journal, as noted on the journal's author guideline page, have been adhered to. No ethical approval was required as this is a case report with no original research data.

DATA AVAILABILITY STATEMENT
Data sharing not applicable to this article as no datasets were generated or analysed during the current study