<?php
	if(is_category()){

		$object = get_queried_object();

		global $wp_query;
		if($wp_query->post_count > 0) {
			if(!empty($wp_query->posts)){

				$post_cats = array();
				foreach($wp_query->posts as $catpost){
					$post_categories = wp_get_post_categories( $catpost->ID );
					foreach($post_categories as $c){
						if($c != $object->term_id){
					 	 $post_cats[] = $c;
						}
					}
				}

				if(!empty($post_cats)) {
					$post_cats = array_unique($post_cats);
					$catstring = '';
					foreach ($post_cats as $cats) {
						$catstring .= $cats . ',';
					}
					$catstring = trim($catstring, ', ');
					wp_list_categories('include='.$catstring);
				}
			}
		}
	}
?>