What is a Tailor's Bunion?
A tailor's bunion (AKA bunionette) is an enlargement of the fifth metatarsal bone at the base of the little toe. Though not as common as bunions , they both have similar symptoms and causes.
The symptoms of a tailor's bunion include redness, swelling, and pain at the site of enlargement. These are caused by wearing shoes that rub against the bunion. 

Causes of a Tailor's Bunion
Tailor's bunions are usually caused by an inherited abnormal foot structure, causing the fifth metatarsal bone to protrude outward, while the little tow moves inward. This causes a bump on the outside of the foot that is easily irritated any time a shoe presses against it.
In some cases, a tailor's bunion may be a bone spur on the side of the end of the fifth metatarsal bone nearest to the toe. Heredity is the main cause of these spurs.

Diagnosis
Tailor's bunion is easily diagnoses due to the obvious protrusion on the foot. Even so, your podiatrist may order x-rays to determine the cause and extent of the deformity.