Pleuroparenchymal fibroelastosis: a rare idiopathic interstitial pneumonia

- A 42-year-old female non-smoker presented with dry cough and progressive exertional dyspnoea. Previous medical history included childhood asthma, breast cancer, and pneumothorax treated with drainage and pleurodesis.

- A 26-year-old male non-smoker with worsening of dyspnoea on effort and non-productive cough. Previous medical history included Cattleman's disease, splenectomy and epilepsy.

- Case 1
The chest X-ray showed a progressive upper lobe volume loss, shrinkage and distortion of the pulmonary hila and apical pleural thickening (Fig. 1).

The HRCT showed upper lobe volume loss, architectural distortion, traction bronchiectasis, reticular abnormalities and pleural thickening with subpleural parenchymal consolidations, mainly in the upper lobes (Fig. 2).

Lung biopsy had been previously performed, and the pathology showed subpleural parenchymal fibroelastosis.

- Case 2
The chest X-ray showed bilateral pleural thickening of apical predominance with reticular interstitial pattern more prominent on the left and upper lobes volume loss (Fig. 3).

The HRCT showed bilateral pleural thickening with subpleural irregular opacities more prominent in the left apex, architectural distortion, multiple traction bronchiectasis, ground-glass opacities and upper lobes volume loss (Fig. 4).

The patient underwent bilateral lung transplantation.

Microscopic examination of the explant showed pleural fibroelastosis in the upper lobes and a pattern of nonspecific interstitial pneumonia in the lower lobes (Fig. 5).

Pleuroparenchymal fibroelastosis (PPFE) is a rare condition that consists of fibrosis involving the pleura and subpleural lung parenchyma, predominantly in the upper lobes [1, 2].
This entity was first coined in 2004 by Frankel et al. [3], although the same concept designated as idiopathic pulmonary upper lobe fibrosis was proposed in 1992 by Aminati and colleagues [4].
The PPFE is now listed as one of the rare idiopathic interstitial pneumonias (IIPs) in the updated classification of IIPs of the American Thoracic Society/European Respiratory Society [1].
There are no reliable data on the incidence and prevalence [5].
Little is known about its aetiology, and many cases have been regarded as idiopathic [6], however, a considerable number of patients with PPFE have underlying diseases or conditions that might be relevant to its occurrence and development, including radiation, anticancer chemotherapy, bone marrow transplantation, lung transplantation, occupational dust exposure, infections, pneumothorax, autoimmunity, and a possible genetic predisposition [6, 7, 8, 9].
Age at onset is wide-ranging, from young to old age, with a median age of 57 years [2, 7]. There is no gender predilection [1, 2, 7] and patients are most often non-smokers [7].
The main symptoms are nonproductive cough and exertional dyspnoea. Such symptoms appear insidiously. Chest pain due to pneumothorax may be the first symptom [7].
Although surgical lung biopsy or autopsy is essential for the definite diagnosis, imaging findings are also essential as the first step to the final diagnosis.
At the early stage of idiopathic PPFE, bilateral apical pleura appear irregularly thickened on the frontal view of chest radiographs. Later, chest radiograph shows marked apical pleural thickening associated with superior hilar retraction. Subsequently, reticular and nodular opacities appear in the bilateral upper lung fields, and hilar opacities are further elevated [5].
HRCT shows dense pleural and subpleural consolidation with a reticular pattern, predominantly in the upper lobes, traction bronchiectasis, architectural distortion, and upper lobe volume loss [1, 5]. In contrast to such changes in the upper lobes, changes in the middle and lower lobes are minimal. As the disease progresses, the opacities extend to the adjacent lobes [5].
PPFE is histologically characterized by alveolar collapse with subpleural elastosis and intra-alveolar fibrosis, in addition to the thickening of the pleura mainly in upper lobes [5, 8, 10, 11].
The clinical course of this affection is progressive and prognosis is poor, although some cases take years to develop, others rapidly progress to respiratory failure, with no therapeutic options other than lung transplantation available [5].