Pulmonary inflammatory pseudotumor

Last revised by Dr. John Yasmer on 27 Dec 2018

Pulmonary inflammatory pseudotumors are solid, non-neoplastic masses which can mimic pulmonary malignancy.

They should not be confused with pulmonary pseudotumors which usually refer to loculated collections of pleural fluid mimicking a pulmonary mass on chest radiography.

Thought to occur from an uncontrolled response to lung tissue injury. Lesions are typically solitary with a lower lobe predilection.

Pathologically, pulmonary inflammatory pseudotumors 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.

Features on chest radiographs 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.

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.

  • some authors advocate resection 4

The differential can be quite wide, including most of those for a solitary pulmonary nodule, but specific considerations include:

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Cases and figures

  • Case 1
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