High resolution CT and histological findings in idiopathic pleuroparenchymal fibroelastosis: Features and differential diagnosis
© S et al.; licensee BioMed Central Ltd. 2011
Received: 18 February 2011
Accepted: 23 August 2011
Published: 23 August 2011
Idiopathic pleuroparenchymal fibroelastosis (IPPFE) is a recently described clinical-pathologic entity characterized by pleural and subpleural parenchymal fibrosis, mainly in the upper lobes. As this disease is extremely rare (only 7 cases have been described in the literature to date) poorly defined cases of IPPFE can go unrecognized.
The clinical course of disease is progressive and prognosis is poor, with no therapeutic options other than lung transplantation currently available, yet. The aim of this report is to describe two further cases of this rare disease, reviewing CT, clinical and histological features.
Idiopathic pleuroparenchymal fibroelastosis (IPPFE) is an entity characterized by pleural and subpleural parenchymal fibrosis. It is extremely rare (only 7 cases have been described in the literature to date) and was first described in 2004 by the Interstitial Lung Disease Program of the National Jewish Medical and Research Center of Denver .
Actually between 1996 and 2001, 5 cases were registered as cryptogenic syndrome with significant chest symptoms, radiographic pleura-parenchymal abnormalities and fibroelastotic changes seen on surgical biopsy specimens, without any evidence of other connective tissue disease . Marked apical pleural thickening associated with superior hilar retraction is present at chest X ray analysis, and High Resolution Computed Tomography (HRCT) shows pleural thickening, fibrosis, architectural distortion, traction bronchiectasis and honeycomb lung . The clinical course of this affection is progressive and prognosis is poor, with no therapeutic options other than lung transplantation available.
We here describe two additional cases of this rare disease.
In both cases described in this letter, the histology corresponded to that previously described for IPPFE [1, 2]. Visceral pleura was diffusely and markedly thickened by a mixture of elastic and dense collagen fibers, with sparing of adjacent lung parenchyma (Figure 2 and 4). Although the transition from fibroelastosis to normal parenchyma was abrupt, elastic fibers variably extended to adjacent alveolar walls. Some fibroblast foci were observed in both cases covered by alveolar epithelium at the boundary between the fibroelastosis and normal parenchyma. Scattered alveolar structures were covered by cuboidal type-II pneumocytes, as defined by the immunohistochemical expression of cytokeratin 8/18 and surfactant-protein-A. These alveolar structures were also entrapped within the fibroelastotic subpleural tissue, together with numerous vessels, including podoplanin-expressing lymphatic vessels (Figure 2A and 4B).
The differential diagnosis of IPPFE includes: asbestosis, connective tissue diseases, advanced fibrosing sarcoidosis and radiation or drug induced lung disease. Radiological and histological features of IPPFE may overlap with that disorders that mainly involve the upper lobes: chronic hypersensitivity pneumonitis and apical caps. In hypersensitivity Pneumonitis (HP) lesions are bronchiolocentric and bronchiolization of the centrilobular airways is prominent. Apical caps may be difficult to distinguish from IPPFE and probably the difference in mainly quantitative. Differential diagnosis could be often reached on the basis of clinical and radiological features: IPPFE is an interstitial lung disease in opposite to apical cap [2,3]. In the histological setting, a last differential diagnosis may be done with findings observed in emphysematous scars at the apex of lung. Also, in smoking-related disease, a ialine fibrosis surrounding subpleural and centrilobular emphysema can be seen: it could make easier the differential diagnosis. It needs to be underlined, that probably IPPFE is, as far as we know, a not specific morphological reaction that might be associated also to different causes or settings. The possibility of IPPFE should be considered when radiological evidence is not consistent with well-defined idiopathic pneumonias that affect upper lobes.
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
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