We present the 2-D photometric decomposition of the Virgo galaxy IC3328 .
The analysis of the global light distribution of this morphologically classified nucleated dwarf elliptical galaxy ( dE1 , N ) reveals a tightly wound , bi-symmetric spiral structure with a diameter of 4.5 kpc , precisely centered on the nucleus of the dwarf .
The amplitude of the spiral is only three percent of the dwarf ’ s surface brightness making it the faintest and smallest spiral ever found in a galaxy .
In terms of pitch angle and arm winding the spiral is similar to the intermediate-type galaxy M51 , but it lacks the dust and prominent H ii regions which signal the presence of gas .
The visual evidence of a spiral pattern in an early-type dwarf galaxy reopens the question on whether these dwarfs are genuine rotationally supported or anisotropic stellar systems .
In the case of IC3328 , we argue for a nearly face-on disk ( dS0 ) galaxy with an estimated maximum rotation velocity of v _ { \mathrm { c,max } } \approx 55 km s ^ { -1 } .
The faintness of the spiral and the small motions within it , suggests that we could be seeing swing-amplified noise .
The other possibility is a tidal origin , caused by the near passage of a small companion .