Abstract
Dear Editors,
We previously reported the case of a 10-year-old spayed Chinchilla cat with spinal anaplastic astrocytoma. 1 The intramedullary tumour was removed surgically, and a 3.5 year follow-up revealed neither recurrence of clinical signs nor a mass on MRI (Figure 1a,b). However, an unexpected clinical course was observed subsequently.
The cat presented at our clinic with a sudden-onset tetraplegic episode 4 years and 11 months after the first surgery. Neurological examination revealed non-ambulatory tetraparesis, absence of proprioception and normal-to-heightened spinal reflexes in all four limbs, with all other neurological findings being normal. Neuroanatomically, the tumour was suspected to be localised to the C1–C5 spinal cord segments. MRI revealed an elliptical intramedullary mass at the C4 level (Figure 1c). The localisation and signal intensities of this mass were identical to those of the previously removed tumour.
A second surgery was performed with a surgical microscope (OPMI PROergo; Carl Zeiss Meditec). Following midline incision of the dura, the pial membrane and spinal cord were incised at the midline because the mass was not visible through the dura, as in the first surgery. The mass was dissected from the parenchyma by using a combination of gentle traction and blunt dissection. The border between the mass and spinal cord appeared clearly demarcated. On the basis of histological findings, we diagnosed the mass as anaplastic astrocytoma. The cat was ambulatory 2 weeks after surgery with slight tetraparesis. Cutaneous itching, thought to be paresthesia caused by surgical invasion to the dorsal funiculus, developed after surgery, but was controlled with pregabalin (2 mg/kg twice daily [Lyrica; Pfizer]). The cat developed seizures 4 months after the second surgery, and died following a seizure 8 months after the second surgery (5 years and 7 months after the first surgery, at the age of 16 years). Unfortunately, the cause of death remains unknown because a postmortem examination was not performed.
In the present case, a tumour of the same pathological type occurred at the same site 4 years and 11 months after surgical resection. Because anaplastic astrocytoma is a malignant tumour with a highly invasive nature, it is reasonable to assume that the second tumour was a recurrence, even though it appeared to have been removed completely during the first surgery and had not recurred during the 3.5 year follow-up period. This clinical course suggests that an absence of imaging findings of recurrence 3.5 years after spinal anaplastic astrocytoma surgery does not necessarily suggest that the surgery was curative. Although the timing of recurrence of feline spinal tumours is unclear because of the rarity of such cases, a long postoperative follow-up period is necessary for evaluating the prognosis.
