Disclosed is a lighting device (10) comprising a heat sink (30) having an annular portion (31) including an annular surface portion (33) delimiting a central aperture (37), said annular surface portion (33) carrying a plurality of SSL elements (50); and a bulbous member (20) cooperating with the heat sink (30), said bulbous member (20) having a first surface portion (21) opposite said SSL elements (50) and a second surface portion (22) extending from said first surface portion (21) through said central aperture (37); wherein the bulbous member (20) is used as a light guide member for light emitted by the plurality of SSL elements (50). A luminaire including such a lighting device (10) is also disclosed.