According to a case report recently published in The American Journal of Gastroenterology, systemic mastocytosis (SM) may cause fluid buildup in the abdomen that initially resembles cirrhosis, a late stage of liver disease marked by scaring of the liver.
The case describes an 80-year-old woman who experienced two years of progressively worsening abdominal swelling, chronic diarrhea, early fullness when eating and weight loss. Imaging showed large-volume fluid ascites — abnormal buildup of excess fluid inside the abdomen, which is commonly caused by liver disease. Testing also revealed an enlarged spleen, swollen lymph nodes and a nodular liver that raised concerns about cirrhosis.
However, a biopsy revealed that her liver only had mild inflammation and scarring. Blood tests also indicated that the liver was functioning well.
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Analysis of the abdominal fluid showed a pattern commonly seen with portal hypertension, which is increased blood pressure in the blood vessels leading through the liver. However, repeated testing found no infection or cancer cells in the fluid.
Doctors treated her with diuretics, which help the body eliminate excess fluid, but the woman’s ascites persisted. She required repeated procedures to drain large volumes of fluid from her abdomen every two to three weeks.
After doctors investigated persistent swollen lymph nodes and imaging findings that raised concerns about a possible cancer, a bone marrow biopsyBone marrow biopsy A procedure to collect a sample of bone marrow using a needle. Often used to examine the characteristics of mast cells and diagnose SM. eventually confirmed systemic mastocytosisMastocytosis Rare disease caused by the buildup of mast cells. Cutaneous mastocytosis primarily affects the skin and is more common in children, while systemic mastocytosis affects internal organs and is more common in adults..
Learn more about SM signs and symptoms
Doctors treated the women with avapritinib, a targeted therapy for some forms of SM, and her symptoms improved. They discontinued the use of diuretics.
“This case highlights SM as a rare but important cause of refractory ascites,” the researchers wrote.
They note that SM can cause ascites through different mechanisms. In advanced disease, mast cells may infiltrate the liver and contribute to liver scaring and portal hypertension. Alternatively, substances released by mast cells can increase blood vessel permeability, allowing fluid to leak into surrounding tissues even when portal pressure is not elevated.
The case highlights the importance of considering SM when ascites persists despite standard treatment and investigations do not confirm cirrhosis or significant portal hypertension. Identifying the underlying cause may allow doctors to use targeted treatment rather than relying on fluid management alone.
