Polyp

Polyp (from the ancient Greek πολύπους, meaning “many-footed”) is a collective morphological term used to describe any pathological, macroscopically visible tissue growth that protrudes above the surface of the mucous membrane into the lumen of a hollow organ. A polyp may be attached to the wall of the organ by a thin stalk (pedunculated polyp) or have a broad flat base (sessile polyp).

It is important to understand that “polyp” is a descriptive, not a histological, term. It refers to the shape of a mass rather than its cellular structure. Polyps can be benign, precancerous, or malignant. The final diagnosis and clinical significance of a polyp are determined only after histological examination.

Aetiology and pathophysiology

The underlying causes of polyps are diverse and depend on their location and histological type.

The main predisposing factors are:

• Chronic inflammation: Prolonged irritation of the mucous membrane can lead to excessive regeneration and the formation of inflammatory or hyperplastic polyps (e.g., nasal polyps in sinusitis, or bowel polyps in Crohn disease).
• Genetic predisposition: Mutations in certain genes may lead to the development of adenomatous polyps, especially in the colon (e.g., in familial adenomatous polyposis).
• Hormonal disorders: Some polyps, such as endometrial polyps in the uterus, are hormone-dependent.

According to their cellular structure, polyps are divided into neoplastic and non-neoplastic. Non-neoplastic polyps include inflammatory and hyperplastic polyps, which have an extremely low risk of malignancy. Neoplastic adenomatous polyps have the greatest clinical significance. They are true benign tumors (adenomas) and are considered precancerous lesions, as they can eventually transform into cancer (adenocarcinoma).

Clinical Significance and Location

Polyps may occur in any hollow organ lined with a mucous membrane. Clinical manifestations depend on their size, number, and location.

The most common locations are:

• Colon: Adenomatous polyps are precursors of colorectal cancer. Their timely detection and removal (polypectomy) during colonoscopy is the main method of colorectal cancer prevention.
• Nose and paranasal sinuses: Most often caused by inflammation and allergy, leading to difficulty in nasal breathing and chronic sinusitis.
• Uterus and cervical canal: May cause abnormal uterine bleeding and infertility.
• Stomach: Most often polyps are benign, but adenomatous ones require observation or removal.
• Ear: An inflammatory polyp originating in the middle ear is a sign of the chronic suppurative otitis media.
• Larynx: Polyps of the vocal folds cause persistent hoarseness.

Many polyps, especially small ones, are asymptomatic and are discovered incidentally during endoscopic examination. The majority of polyps are treated by surgical removal (polypectomy) with mandatory histological examination.

Differential Diagnosis

The primary diagnostic task when a polyp is detected is to determine its histological type and, accordingly, its potential for malignancy. It is not always possible to visually distinguish a benign hyperplastic polyp from a precancerous adenomatous polyp or a malignant polyp (polypoid cancer) during endoscopy. Therefore, the “gold standard” is the principle that every removed polyp must undergo histological examination. The histological examination results determine further patient management, including the necessity and frequency of follow-up examinations.