Highlight Current Sub-Category in Single Post

I’m trying to highlight the sub-category thats currently being viewed in a Single Post. I found some good help on these forums about doing so with a category, but I’ve run into some issues. If you have any ideas, or can help in any way it’d be greatly appreciated,

https://www.leapfrogwebmarketing.com/clients/creative_expression/archives/category/events

<div id="breadcrumbs">

<?php
	$catsy = get_the_category();
	$myCat = $catsy[0]->cat_ID;
	if(in_category($myCat)) {
?>

	<?php wp_list_categories('child_of=$catsy&orderby=order&title_li=&current_category='.$myCat'); ?>

<?php } ?>		

</div> <!-- end #breadcrumbs -->

Thanks,
Terence