<?php

$ciudad = ["Loja","Quito","Guayaquil" ];
$tabla = "<table>";
$tabla .= "<thead>";
$tabla .= "<tr>";
$tabla .= "<th>Ciudad</th>";
$tabla .= "</tr>";
$tabla .= "</thead>";
$tabla .= "<tbody>";
foreach($ciudad as $clave => $valor){
    $tabla .= "<tr>";
    switch($valor){
        case "Loja";
            $tabla .= "<td bgcolor='#FF0000'>$valor</td>";
            break;
        default:
            $tabla .= "<td>$valor</td>";
            break;
    }

    $tabla .= "</tr>";
}
$tabla .= "</tbody>";
$tabla .= "</table>";

echo $tabla;