Corpus: Pharyngeal tonsil

The pharyngeal tonsil is a singular lymphoid organ situated in the epipharynx, the upper part of the pharynx. It is crucial to differentiate the pharyngeal tonsil from the paired palatine tonsil.

The formation of the pharyngeal tonsil begins in the 16th week of embryonic development, marked by the migration of lymphocytes into the subepithelial tissue of the pharyngeal roof. This tissue continues to grow and expand from birth until around the ages of 5 to 7 years.

Comprising lymphatic tissue replete with numerous lymph follicles, the pharyngeal tonsil is an integral part of Waldeyer's pharyngeal ring. Similar to the lingual tonsil, it is unpaired. Its structure is characterized by many seromucous glands that lead into shallow bays on the tonsil's surface, which is enveloped by the respiratory ciliated epithelium typical of the respiratory tract.

The pharyngeal tonsil plays a critical role in the immune system, serving as a first line of defense against pathogens that invade the throat via the nasal mucosa.

The standard microbial inhabitants of the pharyngeal tonsil include alpha haemolytic streptococci, enterococci, corynebacteria, coagulase-negative staphylococci, neisseria, Haemophilus spp., micrococci, and stomatococci.

In children, the pharyngeal tonsil can lead to the development of adenoid vegetations, commonly known as "polyps". A functional enlargement between the 18th and 24th months of life is typical. A severely enlarged adenoid can obstruct airflow in the nasopharynx, impeding nasal breathing. This forces affected children to breathe through the mouth, resulting in snoring during sleep. In severe cases, an adenotomy may be required.