Ultrastructural features of human juvenile laryngeal papillomas

Expanded Basal Compartment and Disrupted Barrier in Vocal Fold Epithelium Infected with Mouse Papillomavirus MmuPV1

Laryngeal infection with low-risk human papillomaviruses can cause recurrent respiratory papillomatosis (RRP), a disease with severe effects on vocal fold epithelium resulting in impaired voice function and communication. RRP research has been stymied by limited preclinical models. We recently reported a murine model of laryngeal MmuPV1 infection and disease in immunodeficient mice. In the current study, we compare quantitative and qualitative measures of epithelial proliferation, apoptosis, differentiation, and barrier between mice with MmuPV1-induced disease of the larynx and surrounding tissues and equal numbers of uninfected controls. Findings supported our hypothesis that laryngeal MmuPV1 infection recapitulates many features of RRP. Like RRP, MmuPV1 increased proliferation in infected vocal fold epithelium, expanded the basal compartment of cells, decreased differentiated cells, and altered cell–cell junctions and basement membrane. Effects of MmuPV1 on apoptosis were equivocal, as with RRP. Barrier markers resembled human neoplastic disease in severe MmuPV1-induced disease. We conclude that MmuPV1 infection of the mouse larynx provides a useful, if imperfect, preclinical model for RRP that will facilitate further study and treatment development for this intractable and devastating disease.

A Novel In Vivo Model of Laryngeal Papillomavirus-Associated Disease Using Mus musculus Papillomavirus

Recurrent respiratory papillomatosis (RRP), caused by laryngeal infection with low-risk human papillomaviruses, has devastating effects on vocal communication and quality of life. Factors in RRP onset, other than viral presence in the airway, are poorly understood. RRP research has been stalled by limited preclinical models. The only known papillomavirus able to infect laboratory mice, Mus musculus papillomavirus (MmuPV1), induces disease in a variety of tissues. We hypothesized that MmuPV1 could infect the larynx as a foundation for a preclinical model of RRP. We further hypothesized that epithelial injury would enhance the ability of MmuPV1 to cause laryngeal disease, because injury is a potential factor in RRP and promotes MmuPV1 infection in other tissues. In this report, we infected larynges of NOD scid gamma mice with MmuPV1 with and without vocal fold abrasion and measured infection and disease pathogenesis over 12 weeks. Laryngeal disease incidence and severity increased earlier in mice that underwent injury in addition to infection. However, laryngeal disease emerged in all infected mice by week 12, with or without injury. Secondary laryngeal infections and disease arose in nude mice after MmuPV1 skin infections, confirming that experimentally induced injury is dispensable for laryngeal MmuPV1 infection and disease in immunocompromised mice. Unlike RRP, lesions were relatively flat dysplasias and they could progress to cancer. Similar to RRP, MmuPV1 transcript was detected in all laryngeal disease and in clinically normal larynges. MmuPV1 capsid protein was largely absent from the larynx, but productive infection arose in a case of squamous metaplasia at the level of the cricoid cartilage. Similar to RRP, disease spread beyond the larynx to the trachea and bronchi. This first report of laryngeal MmuPV1 infection provides a foundation for a preclinical model of RRP.

Human Fibroblast Interferon Adjuvant to CO2 Laser in the Treatment of Recurrent Juvenile Laryngeal Papillomatosis: Experience with 7 Cases

Preliminary results of adjuvant human fibroblasts interferon (IFN beta) given after CO2 laser excision in recurrent laryngeal papillomatosis in 7 adult patients are reported. Diagnostic procedure included histologic and immunohistochemical investigations to demonstrate the presence of viral cytopathic effect and for characterization of the virus. All patients underwent CO2 laser excision under general anesthesia followed by administration of IFN beta intramuscularly at the dose of 4x106 IU/day for 10 consecutive days. In the presence of complete remission, patients were followed without further therapy; in the presence of partial remission, a new combined treatment was established. All patients had a complete remission after combined treatment, but 4 subsequently developed recurrences. Treatments were always well tolerated; even cirrhotic patients showed no side effects.

Juvenile laryngeal papillomatosis: report of five cases from Papua New Guinea

Five cases of juvenile laryngeal papillomatosis encountered in Papua New Guinea during the period from December 1987 to May 1989 are described in detail. They were seen in the age-range of 1 year 7 months-5 years. The common clinical features were change of voice and dyspnoea. They were treated by microlaryngoscopic excision with cupped forceps. One of the cases followed-up for 15 months showed multiple recurrences. This condition of juvenile laryngeal papillomatosis, though not common, is certainly not rare in this country and should be considered as a differential diagnosis in the case of a child presenting with progressive dyspnoea.

Juvenile laryngeal papillomatosis

From the records of 23 patients with juvenile laryngeal papillomatosis, various aspects of the aetiology, natural history and treatment of the condition have been presented. The lesions are thought to be viral in origin, they are notoriously unpredictable in their behaviour, and treatment can often be prolonged and frustrating. Tracheostomy should be avoided, if possible, owing to the risk of further dissemination down the trachea and bronchi. The CO2 laser now seems to be the surgical treatment of choice, and early reports of adjuvant interferon therapy are encouraging. However, the laser is only available in certain centres, and interferon supplies are limited at present.

Laryngeal papillomas

Laryngeal papillomatosis is a serious and potentially life-threatening disease. Like other HPV-induced lesions, these papillomas show an unpredictable pattern of active disease and remissions. The mechanism of benign tumor-induction by the virus, and the possible mechanism of conversion to a malignant lesion after radiation therapy is unknown. Surgery, possibly in conjunction with interferon therapy, is the best course of management at this time.

Ultrastructural features of the adult laryngeal papilloma

The ultrastructural features of nine laryngeal papillomas of the adult type were examined by transmission and scanning electron microscopy. The surface was covered by numerous microvilli varying in size and shape and often arranged in parallel cords. Although we did not find virus-like particles, the ultrastructural characteristics of the adult type of laryngeal papilloma did not differ from those previously found on the juvenile type. The two types may in nature be one and the same lesion, differing in behaviour because of the different environments.

Interferon therapy in juvenile laryngeal papillomatosis

Seventeen patients with severe juvenile laryngeal papillomatosis (12 in Stockholm and five in Umeå) were treated with exogenous leukocyte interferon (IFN-alpha) prepared in Helsinki and Umeå, respectively. Tumor progression occurred in all cases before treatment. During treatment tumor growth diminished in all cases, up to complete tumor disappearance. Of 17 patients, nine were cured and no longer are being treated, four exhibit no tumor growth but are still being treated, one has visible tumor but only slight growth, two still have active but diminished growth, and one, who has refused further treatment, is experiencing active tumor growth as before the start of interferon therapy. It is concluded that IFN-alpha therapy in a dosage of 3 X 10(6) units three times a week intramuscularly can arrest papilloma growth. Further trials are needed to optimize treatment.

Juvenile laryngeal papilloma: histologic and photometric evaluation of atypia

Juvenile papillomas are the most common proliferative laryngeal lesion in children. Atypia may be present but is difficult to interpret owing to the basically benign character of the lesion. A histologic and clinical classification of 23 cases of juvenile laryngeal papillomas was performed following the criteria suggested by Quick and co-workers in 1979 and intended to enable the clinical course to be more accurately predicted. The various histologic types of papillomas were characterized by single-cell microdensitometry. The photometric study verified the increase in the relative width of the proliferative zone with the degree of atypia. Severe atypia was the only histologic type associated with hypertetraploid nuclei. The frequent occurrence of mild atypia was unrelated to the clinical course. The moderate and severe degrees of atypia were more common during periods of relatively frequent operations. Severe atypia was rare but in one patient it heralded the development of invasive carcinoma.

Studies on human Laryngeal papilloma. Degeneration of lymphocytes within the neoplastic cells

Biopsies from 5 cases of Juvenile Laryngeal Papilloma were studied by electron microscopy. In 2 cases, phagocytosed neutrophils were seen in various stages of degeneration and disintegration within the neoplastic cells. The possible phenomenon of "emperiopolesis' and "phagocytosis' in a benign neoplasm is described, and it is suggested that all cases of Juvenile Laryngeal Papilloma must be carefully examined by light- and electron microscopy in an attempt to locate any phagocytic activity in the neoplastic cells which may provide evidence for the early detection of malignancy.

[Viruses, virus-like and virus-related structures in nasopharyngeal carcinoma (author's transl)]

Five cases of nasopharyngeal carcinoma with typically elevated EB-virus-antigen-titer were studied by light- and electron microscopic methods. Within the cytoplasm corona viruses in different forms, regular capsid-like particles with a diameter of 60 nm, tubuloreticular aggregates, and pathologic alterations of the membranes of the endoplasmatic reticulum could be found. The nuclei of the tumour cells often showed particles within the nucleoplasm with an average diameter of 100 nm containing a central core; the appearance of the particles is similar to that of herpes viruses as shown in the literature concerning EB-viruses. Atypic mitoses are common as well as free nucleoplasma-like condensates within the ground cytoplasm. Multiple doubling of the membranes of the endoplasmatic reticulum are characteristic for the tumor cell cytoplasm. Myelin figures are often situated within the enlarged tubules of the E. R., within mitochondria and within the nuclei. The results are discussed concerning the possible viral etiology of nasopharyngeal carcinoma. We do not believe that the particles found within the nucleoplasm have a relation to nuclear pores. The arguments are discussed.

Light and electron microscopic investigations of nasopharyngeal carcinomas with regard to the viral etiology of these tumors

Five carcinomata of the nasopharynx (four lymphoepithelial carcinomata of the Regaud type and one squamous cell carcinoma) were examined light and electron microscopically. In addition to the familiar histological and cytological features of these tumors, and because of an increased antibody titer against Epstein-Barr virus in all five patients, all those cytoplasmic and nuclear inclusions were examined which could be interpreted as indicative of a virus contact. The following structures were found: 1. Particles and microtubules which correspond in diameter, shape, and location to Corona viruses. 2. Particles surrounded by a double membrane and resembling in form and diameter Oncorna viruses. 3. Tubulo-reticular, coil-shaped cytoplasmic inclusions interpreted as an unspecific reaction of the host cell to viral attack. 4. Spherical nuclear bodies, which are frequently observed in tumors and in viral infections. 5. Intranuclear particles which correspond in diameter, structure, and distribution to viruses of the herpes type such as have been described in cell cultures of Burkitt lymphoma and nasopharyngeal carcinoma. The fifth group particularly was discussed in detail with regard to differentiation between those particles and other structures which could simulate a virus structure. Together with the appearance of increased ribosomes and of particular chromatin distribution within the tumor cell nuclei, the particles we discussed have been interpreted as morphological indications of a virus etiology of the examined tumors.

Benign course of juvenile laryngeal papillomata

A 17 month-old child with laryngeal papillomata is presented. The symptoms were stridor and gradually developing dyspnea. He underwent two surgical procedures within 4 months, using microsurgical techniques, and eventually recovered. The etiological factors of this rare entity are discussed. The relatively benign course in our patient is stressed, in view of the usual protracted course which is reflected in the literature.

A new approach to the treatment of laryngeal papilloma in adults

Twenty-six cases of multiple laryngeal papillomatosis were treated by a newly developed grafting technique. The larynx was opened in the midline under local anaesthesia and the tumour mass was surgically resected. Mucous membrane along with the lamina propria was taken from patient's upper jaw and grafted over the wound, with the help of plain catgut on an atraumatic needle. Although our patients have been observed for only a short period of 5 years from 1972, no recurrence has been seen and good vocal cord function has remained.

Viral particles in nasopharyngeal carcinoma

Lymphoepithelioma of the nasopharynx was identified in a 17-year-old Chinese male. The Epstein-Barr virus titer was 1:3200. Tissue from the tumor mass was prepared for electron microscopy. Particles consistent with the morphological characteristics of herpes virus were found within the cytoplasm of malignant epithelial cells. This finding is discussed in relation to other data suggesting an oncogenic role of herpes virus in human malignancy.

Nuclear bodies in laryngeal papilloma

Electron microscopy of Juvenile Laryngeal Papilloma from Nigerian children has revealed the presence of nuclear bodies in the neoplastic cells. These bodies were round or oval in shape and varied from 0.3 to 0.5 micrometer in diameter. The immature forms consisted of fine fibrous units, whereas the mature forms displayed central and peripheral zones. The central zone consisted of dense, coarse, granular filaments, whereas the peripheral zone showed fine filaments of low electron density. Some intermediate forms were also noted. These bodies were similar to those reported in other viral infections and in tumour cells.

The morphology of human papillomas of the upper respiratory tract

Recurrent squamous papillomas of the upper respiratory tract were examined by light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Surface of the cells is irregular and is covered by numerous stout microvilli. These are shorter and broader than those of cells of the uninvolved mucosa. The villi often seem umbilicated at the apex; the remainder of them, however, are rounded. The epithelium participating in the formation of papillomas shows some maturation of the cells but this does not progress normally. The predominating area is the thickened spinous layer representing the bulk of the lesion. The basal layer shows mildly increased activity but the basement membrane is intact. The cells often are very closely packed but in some areas, more particularly in the deep layer, they are loosely arranged. The intercellular space contains a moderately electron-dense finely fibrillar material. No abnormal mitoses are found. The neighboring univolved epithelium often shows increased growth activity and some inflammation. The larygneal papillomas propably represent an overgrowth of epithelium which may develop following hindered desquamation caused and/or heralded by a chronic inflammatory condition probably of viral origin and may be preceded by epithelial metaplasia and hyperplasia.