Endobronchial squamous cell carcinoma from malignant transformation of tracheal papillomatosis

Diagnosis

Endobronchial squamous cell carcinoma from malignant transformation of tracheal papillomatosis </<span class="end-tag" />P><p><B>CASE FOLLOW-UP </<span class="end-tag" />B></<span class="end-tag" />p><P
 
>Bronchoscopic biopsy of the right middle lobe endobronchial lesion revealed dysplastic squamous cell papilloma. Endobronchial brushings were positive for squamous cell carcinoma. Staging evaluation, which included positron emission tomography, was negative for metastatic disease. The patient subsequently underwent a right sleeve pneumonectomy; however, he tragically died secondary to intraoperative &#64258;ash pulmonary edema in the left lung. Postmortem evaluation revealed widespread squamous cell carcinoma throughout the right lung and mediastinum, likely resulting from the malignant transformation of the patient&rsquo;s papillomatosis. </<span class="end-tag" />P

Findings

The initial chest radiograph showed patchy consolidation within the right middle lobe, which was suggestive of pneumonia based upon the clinical &#64257;ndings (Figure 1A). A repeat chest X-ray obtained 6 weeks posttreatment showed worsening right middle lobe consolidation (Figure 1B). Contrast-enhanced CT showed the partial collapse of the right middle lobe with postobstructive pneumonitis. On coronal and sagittal reformatted images, multiple tracheal lesions were identi&#64257;ed (Figure 2); however, no obstructing endobronchial lesions were seen in the region of the right middle lobe bronchus. Virtual bronchoscopy was performed, which identi&#64257;ed multiple tracheal lesions (consistent with tracheal papillomatosis), as well as an endobronchial lesion that was obstructing the right middle lobe bronchus (Figure 3). Subsequent bronchoscopy con&#64257;rmed these &#64257;ndings. </<span class="end-tag" />P

Discussion

Tracheal papillomatosis is a subset of a broader category of recurrent respiratory papillomatosis (RRP). The papillomas are caused by the human papilloma virus (HPV). As in cervical pathology, types 6 and 11 cause benign papillomas, whereas types 16 and 18 have been linked to squamous cell cancer. The disease process is divided into 2 main groups: childhood-onset and adult-onset RRP. The incidence of childhood-onset RRP is estimated to be approximately 4.3 cases per 100,000 children, while the incidence of adult-onset RRP is estimated to be approximately 1.8 cases per 100,000 persons.<Sup>1 </<span class="end-tag" />Sup>The true incidence rate of tracheal papillomatosis is not known because of its rarity as a speci&#64257;c subset of RRP. </<span class="end-tag" />P
><P

>The cause of tracheal papillomatosis in children is thought to be secondary to exposure to the virus during vaginal childbirth.<Sup>2 </<span class="end-tag" />Sup>For adult-onset tracheal papillomatosis, the current belief is that the infection stems from oroanal or orogenital contact with an infected individual.<Sup>3 </<span class="end-tag" />Sup>The course of the disease process varies based upon whether it is the childhood- or adult-onset form; the childhood-onset form is far more aggressive. </<span class="end-tag" />P
><P

>Patients usually present with recurrent respiratory tract infections or obstructive symptoms that can often go undiagnosed or misdiagnosed as asthma or chronic bronchitis. The diagnostic dilemma relates to the rarity of the disease, as well as the slow progression of symptoms. Diagnosis is usually made during a work-up of obstructive symptoms. Computed tomography is the noninvasive modality of choice in detecting lesions within the trachea or bronchi. Once the diagnosis is suggested through noninvasive imaging, bronchoscopic biopsy provides a de&#64257;nitive diagnosis. </<span class="end-tag" />P
><P

>Current treatment modalities for benign papillomas include surgical removal, laser ablation, and a host of antiviral and immune-augmenting medical therapies.<Sup>4 </<span class="end-tag" />Sup>Varying results have been found with each modality; however, surgical removal and laser ablation remain the mainstays of current treatment with adjuvant medical therapy. A very small percentage of patients suffer from malignant transformation of the HPV to squamous cell carcinoma, as was likely the case with our patient. The risk factors for malignant transformation include smoking, prior irradiation, and infection with HPV type 16.<Sup>5 </<span class="end-tag" />Sup>When malignant transformation occurs, treatment typically depends on the stage of the cancer at presentation; however, it is nearly uniformly fatal. </<span class="end-tag" />P
><p><B>CONCLUSION </<span class="end-tag" />B></<span class="end-tag" />p><P

>This case highlights important imaging points. First, adult patients who present with clinical symptoms and radiographic &#64257;ndings of pneumonia should be reimaged posttreatment to exclude an underlying malignancy that can mimic an infectious in&#64257;ltrate.<Sup>6 </<span class="end-tag" />Sup>At our institution, all patients who are 35-years-old or older receive repeat radiographs 6 to 8 weeks posttreatment. If any residual consolidation is identi&#64257;ed, a contrast-enhanced CT scan is recommended to exclude an obstructing endobronchial lesion. </<span class="end-tag" />P
><P

>Second, with the increased utilization of multidetector CT scans, the utility of virtual bronchoscopy will become more evident. We typically perform virtual bronchoscopy on all patients with suspected endobronchial lesions. Additionally, our pulmonary and critical care staff request virtual bronchoscopy as a guide to their bronchoscopic procedures. In the case of this patient, the right middle lobe endobronchial lesion would not have been found (with noninvasive testing) had it not been for the use of virtual bronchoscopy. </<span class="end-tag" />P <OL
type="1"
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