Grabbing “parent” Matrix rows, where the Matrix field has a Playa cell that is relating to a given entry.

gistfile1.html

{exp:channel:entries ... }

    {exp:playa:parents field="matrix_field_name" col="playa_col_name" var_prefix="parent"}
    
        {parent:matrix_field search:matrix_col_name="[{entry_id}]" var_prefix="row"}
        
            {row:some_col_name}
            
            {!-- we can even loop through all of those related entries
                 (which will include the top-level entry) if we want... --}
                
            <ul>
                {row:playa_col_name var_prefix="row_entry"}
                    <li>{row_entry:title}</li>   
                {/row:playa_col_name}
            </ul>
        
        {/parent:matrix_field}
    
    {/exp:playa:parents}

{/exp:channel:entries}