File:Seed derived storage cells - Perforated diverticulitis (50706479398).jpg

These round to oval, convoluted structures are seed-derived storage cells which have leaked into pericolonic tissue as the result of perforated diverticulitis. They exhibit degenerative changes associated with digestion and/or inflammation. There is severe chronic inflammation with scattered giant cells.

The terminology that has been used for these structures is confusing. Although terms such as legume, lentil, pulse and starch granule have been used, these are actually large, seed-derived storage cells. The human diet contains seeds such as lentils, peas, beans, corn kernels and many others. Mature seeds contain an embryo and storage cells; endosperm and/or cotyledon cells. The storage cells provide nutrition to the embryo; they contain starch, protein, and lipid granules in varying amounts. Plants that produce seeds with 1 cotyledon are monocots; those with 2 cotyledons are dicots. The main source of nutrition for the embryo in monocots (corn, coconut, grains, etc) is generally from endosperm cells, and from cotyledon cells (peas, beans, legumes, etc.) in dicots. These 2 cell types are usually difficult to distinguish based on their H&E morphology unless the seed of origin is known. However, distinguishing between them is of no practical significance for pathologists.

According to the Food & Agricultural Organization of the UN ,the term "pulses" is limited to leguminous plants harvested solely for dry grain, thereby excluding crops harvested green for food (green peas, green beans, etc.) which are classified as vegetable crops. Also excluded are those crops used mainly for oil extraction (e.g. soy beans and ground nuts) and leguminous crops (e.g. seeds of clover and alfalfa) that are used exclusively for sowing purposes. 

The type of reaction to the storage cells in this case is frequently referred to as a "pulse granuloma"; a misnomer.