Correct!
3. Tracheobronchial papillomatosis complicated by malignant degeneration
Thoracic CT obtained just over 1 year following presentation, shown in lung and soft tissue windows, shows progression of the thin-walled, nodular cysts into frankly cavitary lesions with grossly nodular walls. The images displayed soft tissue windows show that the cavitary areas contain both internal low attenuation, consistent with necrosis (*) as well as nodular, enhancing foci (arrowheads) related to the internal cavity walls.
While septic embolization certainly can produce nodules that subsequently cavitate, in this patient, cysts and cavities are present initially, subsequently complicated by the development of nodules and masses. Furthermore, the progression of the abnormalities has occurred over years and in the absence of clinical features of infection, making septic embolization very unlikely.
Pulmonary benign metastasizing leiomyomas may cause multiple pulmonary nodules and masses, and even cavitation of the pulmonary abnormalities has been reported in this condition. Typically patients with pulmonary benign metastasizing leiomyomas have a history of uterine leiomyomas who have undergone hysterectomy, and that history was not provided in this case. Additionally, while the pulmonary nodules and masses in patients with benign metastasizing leiomyomas may show growth over time, typically the growth is much slower than that seen in this patient, and the pulmonary abnormalities in such patients are frequently asymptomatic. Finally, the dependent distribution of the pulmonary abnormalities in this patient would not be expected with benign metastasizing leiomyomas.
The extensive nodular and mass-like components of the pulmonary abnormalities in this patient are not consistent with pulmonary lymphangioleiomyomatosis; that condition is dominated by thin-walled cysts, with only small nodules, often reflecting multifocal micronodular pneumocyte hyperplasia, occasionally present. Progressive metastatic malignancy is a prominent consideration for the abnormalities in this patient, and the rate of progression and development of nodular and mass-like components related to the cystic lesions is consistent with that diagnosis. However, no history of extrathoracic malignancy was provided and nor was such apparent clinically. Finally, the small clustered nature of the cysts, in a dependent distribution, as noted on the earliest thoracic CT (Figure 3), would be quite atypical for pulmonary metastatic malignancy. On the other hand, the presence of small pulmonary cysts and nodules located in a dependent distribution, with subsequent enlargement of the cystic lesions, in a young patient, is very suggestive of tracheobronchial papillomatosis. In that setting, the development of nodular components within the cyst walls, progressing to frank masses, is highly suggestive of the development of squamous cell malignancy, which is a known complication of this condition.
Transthoracic fine needle aspiration biopsy of the subpleural right middle lobe mass was performed, and malignant squamous cells were identified at cytopathology. The patient subsequently underwent right pneumonectomy (Figure 6), which provided additional confirmation of the diagnosis.
Figure 6. Gross pathological specimen following right pneumonectomy shows multiple, upper and lower lobe cavities with extensive nodularity of the inner walls.
Diagnosis: Tracheobronchial Papillomatosis complicated by malignant degeneration, with development of multiple squamous cell carcinomas.
References