MADRID (CNA) –– A 10-year-old girl in Spain fulfilled her childhood dream of becoming a Catholic missionary from her hospital bed shortly before dying from a brain tumor this week.

Teresita Castillo de Diego died March 7 in Madrid after three years of fighting a brain tumor.

Fr. Ángel Camino Lamela, an episcopal vicar of the Archdiocese of Madrid for La Paz Hospital, told the young missionary’s story in a letter he sent to all the faithful of the VIII Vicariate.

Camino had been offering Mass at La Paz Hospital February 11 when the chaplains there suggested he visit a seriously ill girl who had an operation scheduled the next day to remove a brain tumor.

“We arrived at the ICU properly equipped, I greeted the doctors and nurses, and then they took me to Teresita, whose mother Teresa was at her bedside,” he said. “A white bandage encircled her entire head, but her face was exposed enough to perceive a truly brilliant and exceptional face.”

The young girl told the priest she loved Jesus very much and wanted to be a missionary.

Deeply moved by her words, Camino replied, “Teresita, I am making you a missionary of the Church right now, and this afternoon I will bring you the document certifying it and the missionary cross.”

The priest then gave the young girl the Eucharist and administered the Anointing of the Sick.

“It was a moment of prayer, extremely simple, but deeply supernatural,” he reflected. “Some nurses joined us and spontaneously took some photos of us …which will remain as an indelible memory. We said goodbye while she and her mother prayed and gave thanks.”

Later that morning at the vicariate, Camino produced the official document installing Teresita as a missionary. He then took the missionary cross and returned to the hospital in the evening.

Teresita asked her mother to hang the cross by her hospital bed, where she could easily see it, saying, “[T]omorrow I'll take it to the operating room. I’m a missionary now.”

Her mother explained to Infomadrid that Teresita was adopted from Siberia and came to Spain when she was three years old. From a young age, she exhibited a strong spiritual life. She used to attend Mass daily at her school in Madrid run by of the Daughters of Holy Mary of the Heart of Jesus.

The tumor in Teresita's brain was first discovered in 2015. The initial treatment with surgery to remove the tumor and chemotherapy was successful. In 2018, however, the tumor began growing again, and the young girl had to undergo a new operation and new treatment in Switzerland.

In January 2021, she returned to the hospital with severe headaches. She entrusted herself to Blessed Carlo Acutis and Venerable Montse Grases.

An operation was initially scheduled for January 11. However, it could not be performed due to complications, including hydrocephalus, or fluid buildup in the brain. Then Teresita and her mother both tested positive for coronavirus, so they had to be put in isolation.

The drain placed in Teresita’s head to remove the excess fluid got clogged and began to fail several times, causing her severe pain. Meanwhile, the tumor continued to grow without the possibility of surgery.

Her mother said the young girl’s strong faith helped her through the situation. “As she had offered up her sufferings, the thought came to me that Jesus was making use of them to save more and more souls,” her mother said, recalling the young girl’s words: “I’m offering it up for the people; for instance, for someone who is ill, for the priests.”

During the last weeks of her life, Teresita reminded her mother of Christ on the cross, particularly when she could no longer drink water, and the nurses put gauze soaked in water in her mouth.

At 9 a.m. on March 7, Teresita died. She was buried the following day. Cardinal Carlos Osoro, archbishop of Madrid, traveled to her wake to support her family with his presence and to offer “some words full of hope that visibly consoled Teresita's parents, relatives and the girl’s young friends.”

Fr. Camino concluded his letter by asking people to “to pray for Teresita and, above all, to entrust yourself to her because I am convinced that she will protect in a special way the entire VIII Vicariate, in which she was constituted a missionary.”