abnormal foam cell morphology foam cell reticulosis an increase in cells with a vacuolated appearance due to abnormal deposition and retention of lipoproteins and derived from or related to the group of cells having the ability to take up and sequester inert particles and vital dyes, including macrophages and macrophage precursors, specialized endothelial cells lining the sinusoids of the liver, spleen, and bone marrow, and macrophages of lymphatic tissue and fibroblasts of bone marrow MP:0009841 MPheno.ontology increased foam cell number