What is Recurrent Respiratory Papillomatosis (RRP)?
Recurrent Respiratory Papillomatosis (RRP) is a non-cancerous condition caused by Human Papilloma Virus (HPV) subtypes 6 & 11. RRP takes the form of benign (non-cancerous) growths (squamous papillomas) in the respiratory tract (from nose down the mouth to the trachea and lungs). It is quite commonly found in the larynx and cause hoarseness of voice. Even after surgical removal of the tumors, it can recur.
RRP can affect infants, young children and adults. In children the average onset age is 3.8 years and for adults in their 30s-40s. It affects both gender equally.
Causes and transmission of RRP
RRP is caused by HPV especially subtypes 6&11. Neonates caught the HPV during vaginal delivery in mothers who are HPV positive and have genital warts during delivery. Adults get it through sexual transmission especially through oral sex.
HPV causes the formation of wart-like non-cancerous growths called papillomas along the respiratory track from the nose to the mouth, down the trachea and to the lungs. The commonest sites of papillomas is at the larynx (voice-box) followed by the trachea.
Clinical features of Recurrent Respiratory Papillomatosis (RRP)
RRP is a rare disorder, some patients may have symptoms for months before diagnosis is made. As RRP commonly occur in the airway tract, it can cause upper airway obstruction (stridor, choking, wheezing and shortness of breath) which is life-threatening. Another common symptom is hoarseness of voice as the larynx if most common site involved.
Other symptoms include a sensation of foreign body in throat, cough and failure to thrive in neonates.
Diagnostic tests for RRP
Diagnosis is made by visualizing the papillomas in the vocal cords/other parts of respiratory track by a laryngoscopy (procedure to view the larynx- vocal cords) or bronchoscopy (procedure whereby a cylindrical fiber optic scope is inserted into the airways).
After confirmation of RRP, a biopsy of the lesion can be done for HPV subtyping and histological studies. HPV subtypes typing can be done with PCR test. HPV subtype 11 is the more dangerous subtype causing more severe diseases and associated with increased risk of cancerous changes.
Imaging studies like Chest X-ray and CT scan may aid in assessing any papillomas in the trachea, bronchus and lungs. Lung function study will aid to see the extent of upper airway obstruction.
Staging of RRP
RRP staging system was published in 1998 using anatomical and clinical parameters to estimate the severity of disease and need for surgical intervention.
Anatomical parameters include number of sites involved and the papilloma appearance (bulkiness, surface appearance and whether it is raised). Clinical parameters include quality of voice, presences and severity of airway obstruction/stridor and urgency for intervention.
Treatment of RRP
Aim of therapy for RRP is to improve voice quality, relieve life-threatening airway obstruction and facilitate remission. Surgery is the primary way of removing the papillomas but they can recur resulting in repeated surgical removal.
Surgical resection may have complications like tracheal stenosis (narrowing/obstruction) and scarring of larynx. If there is tracheal obstruction then a tracheostomy may be necessary. Tracheostomy is a surgical procedure in which an incision is made in the neck and a breathing tube (tracheal tube) is inserted through the opening into the trachea (windpipe) to allow oxygenation of the lungs.
Newer technology of surgery include microdebridement, angiolytic laser, cryotherapy, or carbon dioxide laser. These has less complications like bleeding and tracheal stenosis. Mircodebridement uses suction to hold the papilloma while a small internal rotary blade removes the growth. Newer methods result in shorter operating time and earlier recovery.
Intra-lesional injection of cidofovir into the papilloma, a medication that slows and prevent regrowth of papilloma (inhibit HPV replication) is often combined with surgery to reduce the recurrence of RRP. Other medications like interferon which also prevent recurrence but does not eradicate the HPV may be considered.
Diet rich in cruciferous vegetables (e.g. cabbage, cauliflower, broccoli, Brussels sprouts) may have a favorable effect due to its component indole-3-carbinol.
RRP tends to recur and patients may need repeated surgery. Post-surgery they will be followed up by ENT specialist to look out for recurrence of RRP. The patients will also be seeing the speech therapist to aid in speech phonation and vocal projection.