What is a common cellular shape observed in carcinoid tumors within submucosal tissues?

Carcinoid tumors, which are neuroendocrine tumors often found in submucosal tissues such as the gastrointestinal tract, typically exhibit a cellular morphology characterized by round cells. These cells can be described as having a uniform, rounded appearance and are usually arranged in nests or trabecular patterns within the tumor tissue. The round shape of the cells contributes to the distinctive histological features associated with carcinoid tumors, including their typical low mitotic activity and the presence of cytoplasmic granules when examined under a microscope.

The other cellular shapes mentioned – cuboidal, cylindrical, and squamous – are not typical of carcinoid tumors. Cuboidal cells are more often associated with glandular tissues, cylindrical cells are characteristic of columnar epithelium found in areas like the gastrointestinal lining, and squamous cells are flat and found in areas like the skin and respiratory tract. The specific round shape of the cells in carcinoid tumors is crucial in identifying these tumors and differentiating them from other types of tumors in submucosal tissues.