Argentine President Cristina Fernandez never had cancer despite being diagnosed with the disease last month and having her thyroid gland removed on January 4, her spokesman said on Saturday.
The government announced just after Christmas that the recently re-elected leader had thyroid cancer.
The operation to remove the gland went well, but when it was later analysed it turned out to have never contained cancerous cells, said spokesman Alfredo Scoccimaro.
The original diagnosis has been modified, he told a news conference. The presence of cancer cells was discarded.
Fernandez was originally diagnosed with papillary carcinoma.
Buenos Aires-based thyroid cancer expert Eduardo Faure, who is not on the president's medical team, said a small number of such cases turn out to be false positives, meaning that no cancer is present.
The cells may originally appear to be cancer but in 2 percent of cases, after the operation, when a more thorough examination can be performed, it turns out they are not, the doctor said in an interview.
This result was always within the realm of possibility. It does not mean that the original diagnosis was mistaken.
Several hundred Fernandez supporters had camped out near the hospital where she was treated, carrying banners that said Strength Cristina. A cheer went up from the crowd when Scoccimaro made the announcement.
The president, who won re-election with 54 percent of the vote in October, is popular among Argentines who agree with her generous welfare spending. Business leaders and farmers in the country's key grains sector however say her state-centric interventions in the economy scare away investment.
Vice President Amado Boudou, the former economy minister and a loyal Fernandez ally, assumed the presidency this week during Fernandez's scheduled 20-day leave of absence.
A skilled orator fond of glamorous clothes, high heels and make-up, Fernandez still wears black as she mourns her husband and closest adviser, former President Nestor Kirchner, who died in 2010.
Many thought his death spelled the end of the couple's idiosyncratic blend of state intervention, nationalist rhetoric and the championing of human rights in grains exporting powerhouse Argentina, a major world supplier of soy and corn.
But Fernandez pulled off a remarkable comeback thanks to a brisk economic expansion and an outpouring of public sympathy, setting the stage for her to easily win a second four-year term, which started last month.
(Reporting By Maximiliano Rizzi; writing by Hugh Bronstein; Editing by Doina Chiacu)