Mast cell leukemia with rapidly progressing portal hypertension

Reported herein is an autopsy case of mast cell leukemia, a rare form of systemic mastocytosis, complicated with portal hypertension. A 52‐year‐old woman presented with urticaria‐like skin symptoms, anemia, and thrombocytopenia. Atypical mast cells (CD2+, CD25+, CD117+) with toluidine blue metachromasia were found in the peripheral blood and on bone marrow aspiration smears. Chemotherapy with cytosine arabinoside and idarubicin was ineffective and the patient died of multi‐organ failure with rapidly progressing hepatosplenomegaly and large‐volume ascites 3 months after admission. At autopsy the bone marrow, spleen, liver, and lymph nodes were extensively infiltrated by atypical tumor cells with occasional bi‐ or multi‐lobated nuclei. They were positive for mast cell tryptase and possessed an activating mutation of the c‐kit gene (D816V). Ascites (2200 mL) and non‐ruptured esophageal varices with submucosal hemorrhage indicated the presence of severe portal hypertension. Although there was no evidence of liver cirrhosis, the hepatic sinusoids were clogged with tumor cells, with a tendency to be more severe in the perivenular areas, and the lumens of central veins were obliterated by tumor cell infiltration. The present case demonstrates that non‐cirrhotic portal hypertension due to blocking of sinusoidal and venous flow could be a serious complication in mast cell leukemia.