Carcinoma ex‐papilloma: Histologic and virologic studies in whole‐organ sections of the larynx

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Abstract
A patient with adult-onset recurrent respiratory papillomatosis (RRP), initially diagnosed at age 28 years, was treated with radiation therapy due to the rapid regrowth of lesions. Following 6 years of apparently inhibited growth, papilloma recurred, and squamous carcinoma was diagnosed from a laryngeal biopsy. A spontaneous laryngocutaneous fistula developed, and laryngectomy was performed 14 years after irradiation. The laryngectomy specimen was snap frozen and representative tissues were stored frozen for viral studies. The larynx was whole-organ sectioned for histologic examinations; residual papilloma, as well as carcinoma, was observed. Koilocytosis and other virus-associated histologic changes were also found. HPV capsid antigen was present in papilloma, carcinoma, and clinically normal epithelium. HPV nucleic acids, conforming to HPV type 6, were present in keratin pearls and dysplastic cells. According to prior reports, carcinoma developing in preexisting papilloma arises from juvenile-onset RRP. Irradiated papilloma develop cancer at about 10 years, and the patients rarely survive. Nonirradiated cases develop cancer after 30 years, and some develop papilloma in the hypopharynx and trachea, but most patients survive. Irradiation is not an obligatory precursor for malignant transformation of cancer; however, until now there have been no case reports of favorable outcome after irradiation of papilloma.