Since it’s been around since c1325, I don’t think we can label it American English. From the OED:
bunch noun1
1.a. A protuberance, esp. on the body of an animal; a hump on the back (of a human being, a camel, etc.); a goitre; a swelling, tumour. c1325–
Source: Oxford English DictionaryOxford English Dictionary (login required)