Benign tumors of the larynx refer to true neoplasms that originate in the larynx and possess benign characteristics both clinically and pathologically. These tumors typically arise from epithelial or connective tissue and are composed of highly differentiated mature cells. They do not invade neighboring tissues or metastasize to other locations, are not prone to ulceration, and do not result in cachexia. Laryngeal papilloma is the most common type, while other types include hemangioma, fibroma, neurofibroma, chondroma, and lymphangioma.
Laryngeal Papilloma
Laryngeal papilloma is the most frequently encountered benign tumor of the larynx. It can occur at any age but is more common in children under the age of 10. There is no significant difference in prevalence between males and females. Based on the age of onset, it is classified into juvenile and adult types. The juvenile type predominantly occurs before the age of 5, grows rapidly, has a tendency for local recurrence and spread, is unlikely to undergo malignant transformation, and tends to exhibit a self-limiting course as the child grows. The adult type is more commonly seen between the ages of 20 and 40, often manifests as a solitary lesion, and carries the potential for malignant transformation if recurrent.
Etiology
The condition is widely believed to be caused by infection with the human papillomavirus (HPV). The juvenile form may be associated with maternal genital HPV infection, although cesarean delivery does not appear to completely prevent its occurrence. The mode of infection for the adult form may be related to either latent HPV infection acquired during childhood, lifestyle-related factors, or laryngeal chronic inflammation and endocrine imbalances.
Pathology
Laryngeal papilloma is a tumor of epithelial origin, characterized by papillary growth of stratified squamous epithelium and underlying connective tissue. Microscopically, the surface of the tumor is covered with stratified squamous epithelium, while the core consists of loose connective tissue rich in vasculature. The tumor often does not invade the underlying basal tissue. In juvenile cases, the tumor frequently involves multiple sites and may extend beyond the larynx, affecting areas such as the hypopharynx and trachea. In severe cases, lesions may even grow at the terminal portions of the trachea or near the bifurcation of the main bronchi, posing risks of respiratory distress or even asphyxia.
Clinical Manifestations
Progressive hoarseness is a common symptom. Larger tumors may lead to coughing, stridor, or difficulty breathing. In children, the smaller size of the laryngeal cavity, the rapid growth of the tumor, and the tendency for multiple lesions increase the likelihood of laryngeal obstruction.
During laryngoscopic examination, the tumor appears pale, light red, or dark red, with a surface that is often mulberry-like or rough and shaggy, resembling villi. Tumors in adults are generally solitary, while those in children tend to be broad-based and multiple. They commonly originate in the vocal cords but may extend upward to the ventricular folds and epiglottis or downward to the subglottic area and trachea.
Treatment
Surgical removal remains the primary treatment approach. Among the most common and effective techniques is tumor excision using a CO2 laser under a supportive laryngoscope. Other methods, such as low-temperature plasma ablation, have also been reported for treating laryngeal papillomas. Surgical procedures in children carry certain risks, particularly in cases of respiratory distress, where tracheotomy may be considered as a preliminary step. Ensuring airway patency during surgery is crucial, and the use of a rigid pediatric bronchoscope under general anesthesia is considered optimal. Intraoperative examination of the hypopharynx, subglottic area, trachea, and bronchi should be conducted to identify and address any potential papillomas. Gentle surgical techniques are crucial to avoid dissemination and to protect the normal mucosa.
The risk of recurrence is high in pediatric patients, necessitating multiple repeat surgeries. Families should be informed of this likelihood in advance. In adults with recurrent laryngeal papillomas, special attention should be given to the possibility of malignant transformation. Pharmacological treatments have been explored, but their efficacy requires further evaluation.
Laryngeal Hemangioma
Laryngeal hemangioma is relatively rare and can occur at any age.
Pathology
Laryngeal hemangioma can be classified into two types: capillary hemangioma and cavernous hemangioma. Capillary hemangiomas are more common and are composed of clusters of thin-walled capillaries interspersed with small amounts of connective tissue. They are frequently observed in adolescents and can occur in any part of the larynx, most commonly on the vocal cords. Cavernous hemangiomas are composed of sinusoidal blood vessels, have a spongy texture, and appear dark red. Typically, they lack a stalk and are diffusely distributed beneath the mucosa.
Clinical Manifestations
Based on the time of onset, laryngeal hemangiomas are categorized into juvenile and adult types. The juvenile type can develop within a few months after birth, with lesions often located in the subglottis and glottis, leading to symptoms such as respiratory distress and bleeding. Some affected children may also exhibit hemangiomas in other parts of the body, particularly the skin. The adult type is commonly found around the supraglottic region. When the lesion develops near the vocal cords, it may lead to voice changes.
Treatment
Asymptomatic laryngeal hemangiomas may not require immediate treatment. For those with significant symptoms, interventions depend on tumor size and location and may include cryotherapy, laser therapy, surgical excision, or intralesional injection of sclerosing agents. In cases of large lesions or significant bleeding, tracheostomy may be considered. Biopsy should be conducted cautiously if a hemangioma is suspected.
Laryngeal Fibroma
Laryngeal fibroma is rare and arises from connective tissue. It is composed of fibroblasts and bundles of collagen fibers, with relatively few blood vessels. The size of the tumor varies, ranging from a small, grain-sized lesion to a larger mass that may obstruct the airway. Fibromas most commonly occur in the anterior-middle portion of the vocal cords but can also be found in the epiglottis, ventricular folds, or subglottic region.
The tumor progresses slowly, does not undergo malignant transformation, and primarily manifests as hoarseness. Larger tumors may cause symptoms of airway obstruction. Laryngoscopic examination reveals a firm, smooth tumor that may be pedunculated or sessile, and it appears grayish-white or pale red. The primary treatment for laryngeal fibroma is surgical removal.
Laryngeal Neurofibroma
Laryngeal neurofibroma is uncommon and is usually solitary, though it may occur in association with systemic neurofibromatosis. This tumor originates from nerve fibers and is composed of affected nerve fibers, collagen fibers, and Schwann cells. Recurrent laryngeal neurofibroma has the potential for malignant transformation.
Common symptoms include hoarseness, irritating cough, and discomfort during swallowing. Larger tumors may present with airway obstruction. The tumor tends to occur in areas such as the aryepiglottic fold or ventricular folds. Laryngoscopic examination may reveal a solid, encapsulated mass that is smooth-surfaced and either round or oval in shape. It can protrude into the piriform sinus or obscure the glottis.
CT and MRI scans of the larynx can help determine the location and extent of the tumor. A definitive diagnosis relies on pathological examination. Surgical excision is the primary treatment approach.