Pulmonary inflammatory pseudotumor
Updates to Article Attributes
Pulmonary inflammatory pseudotumours (PIP) are solid, non-neoplastic masses which can mimic pulmonary malignancy.
Terminology
They should not be confused with pulmonary pseudotumours which usually refer to loculated collections of pleural fluid mimicking a pulmonary mass on chest radiography.
Pathology
Thought to occur from an uncontrolled response to lung tissue injury. Lesions are typically solitary with a lower lobe predilection.
Pathologically, pulmonary inflammatory pseudotumours are typically well-defined, firm, lobulated parenchymal nodules or masses with a whorled and often heterogeneous appearance on cross-section.
Histologically, there is a proliferation of spindle-shaped fibroblasts and permeation of collagen with lymphocytes, fibrosis, granulomatous inflammation, lymphoid hyperplasia, and intra-alveolar fibrosis at the edge of the lesion.
Radiographic features
Plain radiograph
Features on chest radiographs can vary but frequently mimics a solitary, well circumscribed-circumscribed, peripheral lung mass with calcifications in situ. May have an anatomical bias for the lower lobes.
CT
CT most commonly shows a well-marginated, lobulated mass of heterogeneous attenuation with variable patterns of contrast enhancement and calcification. Cavitation and lymphadenopathy are rare.
Treatment and prognosis
- some authors advocate resection 4
Differential diagnosis
The differential can be quite wide, including most of those for a solitary pulmonary nodule, but specific considerations include:
- solitary metastases from an osteosarcoma or mucinous tumour
- intra-thoracic soft tissue sarcoma
- pulmonary hamartoma
-<p><strong>Pulmonary inflammatory pseudotumours (PIP)</strong> are solid, non-neoplastic masses which can mimic pulmonary malignancy. They should not be confused with <a href="/articles/pulmonary-pseudotumour">pulmonary pseudotumours</a> which usually refer to loculated collections of pleural fluid mimicking a pulmonary mass on chest radiography.</p><h4>Pathology</h4><p>Thought to occur from an uncontrolled response to lung tissue injury. Lesions are typically solitary with a lower lobe predilection.</p><p>Pathologically, pulmonary inflammatory pseudotumours are typically well-defined, firm, lobulated parenchymal nodules or masses with a whorled and often heterogeneous appearance on cross-section.</p><p>Histologically, there is proliferation of spindle-shaped fibroblasts and permeation of collagen with lymphocytes, fibrosis, granulomatous inflammation, lymphoid hyperplasia, and intra-alveolar fibrosis at the edge of the lesion.</p><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>Features on <a href="/articles/chest-radiograph">chest radiographs</a> can vary but frequently mimics a solitary, well circumscribed, peripheral lung mass with calcifications in situ. May have an anatomical bias for the lower lobes.</p><h5>CT</h5><p>CT most commonly shows a well-marginated, lobulated mass of heterogeneous attenuation with variable patterns of contrast enhancement and calcification. Cavitation and lymphadenopathy are rare.</p><h4>Treatment and prognosis</h4><ul><li>some authors advocate resection <sup>4</sup>-</li></ul><h4>Differential diagnosis</h4><p>The differential can be quite wide, specific considerations include</p><ul>- +<p><strong>Pulmonary inflammatory pseudotumours</strong> are solid, non-neoplastic masses which can mimic pulmonary malignancy.</p><h4>Terminology</h4><p>They should not be confused with <a href="/articles/pulmonary-pseudotumour">pulmonary pseudotumours</a> which usually refer to loculated collections of pleural fluid mimicking a pulmonary mass on chest radiography.</p><h4>Pathology</h4><p>Thought to occur from an uncontrolled response to lung tissue injury. Lesions are typically solitary with a lower lobe predilection.</p><p>Pathologically, pulmonary inflammatory pseudotumours are typically well-defined, firm, lobulated parenchymal nodules or masses with a whorled and often heterogeneous appearance on cross-section.</p><p>Histologically, there is a proliferation of spindle-shaped fibroblasts and permeation of collagen with lymphocytes, fibrosis, granulomatous inflammation, lymphoid hyperplasia, and intra-alveolar fibrosis at the edge of the lesion.</p><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>Features on <a href="/articles/chest-radiograph">chest radiographs</a> can vary but frequently mimics a solitary, well-circumscribed, peripheral lung mass with calcifications in situ. May have an anatomical bias for the lower lobes.</p><h5>CT</h5><p>CT most commonly shows a well-marginated, lobulated mass of heterogeneous attenuation with variable patterns of contrast enhancement and calcification. Cavitation and lymphadenopathy are rare.</p><h4>Treatment and prognosis</h4><ul><li>some authors advocate resection <sup>4</sup>
- +</li></ul><h4>Differential diagnosis</h4><p>The differential can be quite wide, including most of those for a <a title="Solitary pulmonary nodules" href="/articles/solitary-pulmonary-nodules">solitary pulmonary nodule</a>, but specific considerations include:</p><ul>