Vintage.

Modified Item: No
Country/Region of Manufacture: Unknown
Look: Secretary/Geek
Decade: 1980s
Chest Size: 20” Pit To Pit
Original/Reproduction: Original
Features: Tie Neck, Pussy Bow
Color: White
Occasion: casual, dressy, work, everyday, business
Brand: Sears
Shoulder to Hem: 26”
Size (Women's): L
Size Type: Regular

Vtg Vintage 70s 80s 90s White Big Bow Neck Pussy Bow Secretary Blouse

No size tag. Guessing it will fit a modern size L, based on measurements (see size chart in photos): 

armpit to armpit: 20" 

length: 26" 

There is a tiny, light mark (see photos). Probably will come out with bleach.