be a case of (something)

1. To be a bout of a particular illness. A: "My poor daughter has been sick all week with red spots all over her skin." B: "It might be a case of chicken pox." I'd go to the hospital immediately—if it's a case of untreated rabies, you could end up dead sooner than later! If it's a case of necrotizing fasciitis, we have to act fast, or she could end up losing her whole leg.

2. To be an instance or occurrence of something. A: "I don't know why Liz has frozen on the stage like that. She usually loves to sing for an audience." B: "It's probably just a case of nerves." This is clearly a case of political corruption. There's no other explanation for such a large sum of money being in the senator's account. I tried to apologize to the teacher and tell her that I hadn't been trying to interrupt class, that it was just a case of the giggles, but she was furious nonetheless.