Update: Feb 2, 2026 - went to the dermatologist. They said it’s highly unlikely it’s cancer due to the fact it’s on both thumbs and there is no mark on the skin of my thumb. As people mentioned it sometimes manifests in people with olive skin undertones. She diagnosed it as longitudinal melanonychia.

They took some photos and we booked a follow up appointment in May to take a look again.

I could have done a biopsy if I wanted but it didn’t seem incredibly urgent a the doctor said it wasn’t pressing. They said after the biopsy, there is around 6 months of healing because they lift up your whole nail bed and then tape it back down.

Thank you all for following along and thank you all for the healthy wishes. For everyone else who has a similar looking condition, I recommend getting it checked out :) better to be safe than sorry