Danielle Fishel, who played Topanga Lawrence in the 1990s sitcom “Boy Meets World,” announced she has been diagnosed with breast cancer.”I was recently diagnosed with DCIS, which stands for ductal carcinoma in situ. Which is a form of breast cancer,” the 43-year-old said on Sunday’s episode of her “Pod Meets World” podcast she has with former co-stars Rider Strong and Will Friedle.