Signs and Symptoms of Mast Cell Proliferation, Accumulation and Infiltration (Mastocytosis)Advanced disease symptoms may include the following signs of mast cell proliferation, accumulation and infiltration: anemia, thrombocytopenia, ascites, bone fractures, gastrointestinal abnormalities, and enlargement of the liver, spleen, and lymph nodes.1, 2 Mast cell proliferation, accumulation and infiltration can occur in systemic mastocytosis (SM), smoldering SM (SSM), aggressive SM (ASM), SM with an associated hematologic neoplasm (SM-AHN) [previously called “SM with associated clonal hematologic non mast cell lineage disease” (SM-AHNMD)],3 or mast cell leukemia (MCL). B and C findings, in addition to meeting the criteria for SM, clearly define these signs and assist physicians with the diagnosis.