In 2011, a 37-year-old woman in the Democratic Republic of the Congo sought medical help for a large abdominal mass. Despite the large size – doctors estimated it made her abdomen around the size of someone 28-32 weeks pregnant – she experienced surprisingly little symptoms or discomfort from it.
The mass had been there for some time, but other than that she was healthy, having regular periods, and had had five children in her time. However, "in further questioning the patient, she stated that she had been pregnant about three years ago and everything seemed to be going fine, but 'the baby never came out'," her doctors reported.
During exploratory surgery, they found that the mass was not a tumor, but a lithopedion: more commonly known as a stone baby.
"A large calcified spherical mass was delivered through the incision, enveloped with omental adhesions. At this point diagnosis was thought be possibly some type of splenic or mesenteric tumor," the team wrote in their case report.
"The diagnosis was finally made when a shoulder was delivered along with this mass. Finally, after the adhesions were removed, a four pound calcified fetus was removed. This appeared to be approximately a 32-week intra-abdominal pregnancy which had died and calcified."
Images of the stone baby are included in the case report, though of course viewer discretion is advised.
The woman was far from the first to find a calcified fetus in her body. In 1554, in Sens, France, a woman named Colombe Charti was about to give birth when her contractions suddenly stopped. For the remaining 28 years of her life, she would experience abdominal pains. As medicine wasn't quite as advanced as it was today (they were still yet to go through the tricky "wash your hands before you dig around in people's bodies" stage of things), her family did not know what exactly had happened until her death.
Her husband enlisted a surgeon to investigate. Like the woman from the Democratic Republic of Congo, they found what they first thought was a tumor before they saw shoulders, arms, legs, feet, a head of hair, and a single tooth.
There are around 300 cases of stone babies that we know of. Lithopedions are created when a dead fetus is retained inside the body, where it calcifies (where calcium builds up on the tissue, hardening it like bone). They usually occur in abdominal pregnancies, where the fetus has died but is too large to be absorbed by the body.
"When a dead fetus is too big to become reabsorbed by the mother’s body, the immune system treats it as a foreign body," one medical team explain in a case report about one such stone baby. "This induces calcium-rich substance deposition on the fetus that will, in due course, turn the fetus body into stone."
The hard case of calcium that develops around the fetus protects the mother from the dead tissue, protecting her from infection. As a result, people carrying lithopedion are often unaware of it.
"Most of the cases may remain asymptomatic for a long period of time or present with persistent or recurrent abdominal pain and obstructive symptoms of the bowel and urinary system," the team continued.
In 1880, a review of the literature on stone babies looking at 47 cases, Dr Friedrich Kuchenmeister found that the average age a lithopedion was discovered was 55, with the oldest age being 100. The average time people had been carrying them for was 22 years, with one 87-year-old having carried a stone baby for a whole 57 years. She never found this out, however, as it was only discovered during autopsy.