Doublecortin immunolabeling and lack of neuronal nuclear protein immunolabeling in feline gliomas

Abstract

Doublecortin (DCX) and neuronal nuclear protein (NeuN) can be used as immunomarkers of neuronal progenitor cells and mature neurons, respectively. Increased DCX immunolabeling has been associated with tumor invasion in human gliomas and anaplastic canine meningiomas. These immunomarkers have not been assessed in feline gliomas. Here we characterized the DCX and NeuN immunohistochemistry (IHC) profile in 11 feline gliomas (7 oligodendrogliomas, 4 astrocytomas). Immunolabeling was classified according to intensity (weak, moderate, strong), distribution of neoplastic cell immunolabeling (1 = <30%, 2 = 30–70%, 3 = >70%), and predominant location within the neoplasm (random or at tumor margins). DCX immunolabeling was strong in 6 cases, weak in 4 cases, and moderate in 1 case. The distribution of DCX immunolabeling was characterized as 1 (4 cases), 2 (4 cases), and 3 (3 cases). DCX immunolabeling occurred predominantly in astrocytomas, which had stronger immunostaining at the tumor margins. NeuN immunolabeling was absent in all cases. Our IHC findings are similar to those reported for DCX and NeuN IHC in canine gliomas. The increased DCX immunolabeling at tumor margins is similar to labeling in invasive human gliomas and anaplastic canine meningiomas.

Doublecortin immunolabeling in canine gliomas with distinct degrees of tumor infiltration

“…In contrast, DCX immunolabeling in our nodular gliomas was similar to that reported in canine and feline gliomas, 2,3 with strong and random cytoplasmic immunolabeling in most cases. Increased staining at the tumor margins was observed in 2 high-grade oligodendrogliomas with focal and diffuse infiltration and 1 high-grade undefined glioma with diffuse infiltration.…”

“…6 A similar immunolabeling pattern has been observed in feline gliomas, mainly astrocytomas. 2 Given that astrocytomas tend to be more invasive than oligodendrogliomas, these findings may also support the role of DCX in tumor infiltration. However, this correlation was not as clear in other studies, which have suggested that DCX expression by glioma cells may not necessarily reflect their infiltrative potential.…”

“…1 A similar DCX immunolabeling pattern has been reported for anaplastic canine meningiomas and feline gliomas. 2,6 In dogs, tumoral DCX immunolabeling has been reported regardless of glioma subtype (oligodendroglioma or astrocytoma) or grade, but, to our knowledge, no investigations have assessed the DCX immunolabeling pattern in gliomas with distinct degrees of infiltration into the neuroparenchyma. 3 We hypothesized that DCX immunolabeling should be more intense at the margins of invasive gliomas (such as diffusely infiltrating gliomas) compared to less infiltrative gliomas (compact or nodular gliomas).…”

“…When positive, DCX immunolabeling was assessed according to intensity (weak, moderate, or strong), distribution (1 = <30% of neoplastic cell immunolabeling, 2 = 30-70% immunolabeling, 3 = >70% immunolabeling), and predominant location within the neoplasm (random or at tumor margins). 2 All gliomas were diagnosed and graded using tumor morphology aided by IHC for OLIG2 and GFAP (Table 2). 9 Diffusely infiltrating gliomas consisted of low-grade astrocytomas (4 of 14; 28%), high-grade astrocytomas (4 of 14; 28%), high-grade undefined gliomas (3 of 14; 21%), low-grade oligodendrogliomas (2 of 14; 14%), and highgrade oligodendroglioma (1 of 14; 7%).…”

“…DCX immunolabeling has been utilized to detect neuronal differentiation by neoplastic glial cells in human, canine, and feline gliomas. [1][2][3] Increased levels of DCX expression and immunolabeling at the margins of invasive human CNS neoplasms (including gliomas) has been also suggested as In all cases, antigen retrieval was by use of citrate solution 10× (BioGenex), 1:10 dilution, 15 min at 110°C; antibody dilution was 1:4,000, the chromogen used was diaminobenzidine, performed in an autostainer (Nemesis 3600; Biocare). DCX = doublecortin; GFAP = glial fibrillary acidic protein; NA = not applicable; OLIG2 = oligodendrocyte transcription factor 2. evidence that DCX-positive neoplastic cells may have a higher propensity to infiltrate the adjacent neuroparenchyma.…”