Rare Tumor of the Tracheobronchial Tree: Solitary Squamous Papilloma

Solitary bronchial squamous cell papilloma - another human papillomavirus (HPV)-associated benign tumor: systematic review and meta-analysis

Aim of the study

To perform a systematic review and formal meta-analysis of the literature reporting on HPV detection in bronchial squamous cell papillomas (SCP).

Material and methods

The literature was searched up to June 2012. The effect size was calculated as event rate (95% CI), with homogeneity testing using Cochran's Q and I² statistics. Meta-regression was used to test the impact of study-level covariates (HPV detection method, geographic origin) on effect size, and potential publication bias was estimated using funnel plot symmetry.

Results

Fifteen studies were eligible, covering 89 bronchial SCPs from different geographic regions. Altogether, 38 (42.7%) cases tested HPV-positive; effect size 0.422 (95% CI: 0.311–0.542; fixed effects model), and 0.495 (95% CI: 0.316–0.675; random effects model). In meta-analysis stratified by i) HPV detection technique and ii) geographic study origin, the between-study heterogeneity was not significant for either; p = 0.348, and p = 0.792, respectively. In maximum likelihood meta-regression, HPV detection method (p = 0.150) and geographic origin of the study (p = 0.164) were not significant study-level covariates. Some evidence for publication bias was found only among in situ hybridization (ISH)-based studies and among studies from Europe, but with a negligible effect on summary effect size estimates. In sensitivity analysis, the meta-analytic results were robust to all one-by-one study removals.

Conclusions

In formal meta-regression, the variability in HPV detection rates reported in bronchial SCPs is not explained by the HPV detection method or geographic origin of the study.

Solitary papillomas of the lower airways: epidemiological, clinical, and therapeutic data during a 22-year period and review of the literature

INTRODUCTION

Solitary respiratory papillomas (SRPs) are considered uncommon yet benign neoplasms of the lower respiratory tract. Most of our understanding stems from single case reports or limited case series.

OBJECTIVE

To determine the incidence of solitary SRPs and more accurately describe the localization, distribution of subtypes of solitary SRPs, clinical features, and the risk of malignant transformation. This retrospective report is based on data collected in a busy single-center bronchoscopy practice during a 22-year period.

METHODS

Among 36,780 patients who underwent bronchoscopic procedures between 1986 and 2008, we identified 32 patients with SRPs. This patient group was compared with 69 patients with SRPs described in the English literature as case reports, case series, or diagnostic dilemmas.

RESULTS

Twenty-three patients were men (male/female ratio of 3:1), and 21 patients were former smokers (65.6%). The mean age of initial presentation in men and women was 56.9 ± 14.3 versus 53.3 ± 14.4 years, respectively. The presenting symptoms included cough in 18 patients (40.6%), hemoptysis in 11 (25%), dyspnea in seven (21.8%), and fever in five patients (15.7%). Two patients with papillomas in the subglottic region had wheezing and were on aerosolized bronchodilator therapy. In one patient, the papilloma was incidentally discovered on a chest computed tomography scan. The histologic analysis of lesions revealed squamous papillomas in 65.6%, a glandular subtype in 18.75%, and a mixed subtype in 15.6%. Malignant transformation was observed in five patients (15.7%). The malignancies consisted of squamous cell carcinoma in two patients, and single cases of small cell lung carcinoma, glandular carcinoma, and low-grade carcinoma.

CONCLUSION

In our experience, the estimated incidence of SRPs is 3.95 cases/100,000 patients/yr. SRPs occur more commonly in men (ratio 3:1). Squamous papillomas occur commonly during the fifth decade of life, glandular papillomas predominate in the sixth decade, and the distribution of mixed type papillomas is from the third to the sixth decade of life. Malignant transformation was observed in a minority of patients.

Mixed squamous cell and glandular papilloma of the lung: a case study and literature review

Mixed squamous cell and glandular papilloma (mixed papilloma) of the lung is an extremely rare neoplasm, with only 10 cases reported so far in the English literature. We present a case study of endobronchial mixed papilloma with immunohistochemical and etiological investigations. A 49-year-old male with a smoking history complained of hemoptysis, presented with a lung mass closely adjacent to large vessels in the computed tomography findings, and underwent lobectomy. The 3.0-cm sized polypoid tumor was histologically diagnosed as endobronchial mixed papilloma. Immunohistochemically, intracellular mucin was positive for MUC5AC, which is expressed in tracheobronchial goblet cells. CAM5.2 and CK19 were diffusely positive, indicating that the tumor originated from the columnar epithelium by squamous metaplasia. CEA and CA19-9 were focally positive. A human papillomavirus (HPV) investigation with in situ hybridization using a wide spectrum probe and a newly-developed PCR system did not detect any HPV infection. Including this case with a detailed HPV investigation, all of the reported cases of mixed papilloma were HPV-negative, and a literature review including newly-reported cases indicated a high frequency of smoking in such cases. Endobronchial mixed papillomas might have a smoking-related etiology.