Do you have copy number information for this sample? In my cancer samples, it is common to have X duplications in XY-originating tumors that can cause something like this, which is why I do additional downstream analysis to consider copy number context in my variant calling.
I have a conflict of interest because this is my lab's software, but TitanCNA is a tool I use on a weekly basis for identifying variants using SNPs (from GATK or other variant callers) and copy number context (from ichorCNA) together: https://github.com/gavinha/TitanCNA
AN is the number of alleles at that position, and AF is the allele frequency, so I would interpret your data as meaning that your subject is heterozygous at that position. See the VCF Specification linked below: