US country music star Ashley Monroe has revealed she has been diagnosed with a rare form of blood cancer.

The 34-year-old musician, who is a member of the band the Pistol Annies, said she was told she has Waldenstrom macroglobulinemia (WM), a type of non-Hodgkin's lymphoma, and will start chemotherapy this week.

Pistol Annies

Sharing photos of herself holding a bunch of flowers, as well as shots of her with her son Dalton and husband John Danks, as well as friends including country superstar Miranda Lambert, she wrote: "Gratitude. Moments like these I am overwhelmed with gratitude.

"Getting flowers delivered weekly from @genajohnson507. Enjoying a staycation in Nashville when we had to cancel our Florida trip. Sitting with my sisters the day I found out.

"Seeing John be my rock and the best dad to Dalton, and being surrounded (and prayed for) by the best friends (and family and manager) I could ever dream up.

"A few months ago my dr. was doing some routine lab work and found that I was anemic. I was like, FINE, I’ll just double up on cheeseburger patties, take some extra vitamins and call it a day.

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"Well my red blood count just kept falling, and they found out my iron /b12/ folic acid numbers were actually fine. short story long, they did a bone marrow biopsy, (ouch), and VOILA.. a rare kind of blood c word called 'waldenstrom macroglobulinemia.’

"It’s causing my body to be pretty severely anemic, and I feel it.

"So, I start chemo tomorrow. Seems like such a negative thing to say. Until I flip that doom feeling on its head and think, wow, I’m thankful I have an illness that is VERY live with-able.

"I’m thankful there IS a treatment that actually works to fight what is causing harm to my body.

"THANKFUL for friends and family who have gathered around me praying and sending flowers and letting me lean on them during this super weird chapter of my life.

"Thankful for my angel son. Who I am fighting for the most."

Monroe, Lambert and Angaleena Presley formed the Pistol Annies in 2009. Their hits include Got My Name Changed Back and Best Years Of My Life.