DPO: Diffuse Pulmonary Ossification - A Diagnostic Challenge

Abstract

Diffuse pulmonary ossification (DPO) is a rare condition of DLD (diffuse lung disease) characterized by the presence of metaplastic ectopic bone in the lungs and is less frequent in patients without a clear background of lung diseases. DPO is characterized by very small calcific nodules, often with bone mature located in both lungs and often in peripheral areas of the lungs. Two patterns of DPO have been recognized dendriform and nodular. The dendriform type is less common and is characterized by a coral-like network of bone spiculae along the alveolar septa and is often related to interstitial fibrosis or chronic obstructive lung disease [1]. Recent literature papers indicate that DPO may be a predictor of pulmonary fibrosis, is related to Usual Interstitial Pneumonia (UIP) pattern, and has a higher correlation with Idiopathic Pulmonary Fibrosis (IPF). We present a case of a 41-years-old male with persistent bronchitis who underwent a chest X-ray (CXR) that showed multiple pulmonary small calcified nodules in both lungs. These findings were then defined with a high-resolution computed tomography of the chest (HRCT) that showed multiple small nodules spread in both lungs with a "tree-like pattern". A lung biopsy was performed to confirm the radiological diagnostic hypothesis of DPO, and further pathological examination showed multifocal areas of mature bone tissue within the lung parenchyma.

Keywords: DPO; Diffuse; Lung; Ossification; Pulmonary.

Fig. 1

CXR: In both lungs are visible branching and nodular calcific small opacities.

Fig. 2a

CT scan lung windows (1.25 mm collimation) of lower lung lobes: nodular thickening of contiguous interlobular septa and subpleural tiny nodules in posterior and lateral basilar segments of both lower lobes. Absence of distortion and/or traction bronchiolectasis.

Fig. 2b

CT scan lung window MPR coronal view: nodular thickening of contiguous interlobular septa and subpleural tiny nodules in both lower lobes. Absence of distortion and/or traction bronchiolectasis.

Fig. 3

PET/CT examination: not significant increase in metabolic activity in both lungs.

Fig. 4

Lung tissue with ossification (left) in the alveolar space (Hematoxylin and eosin stain, 10×).