Pictorial essay: multimodality imaging of metastases from pancreatic ductal adenocarcinoma

CT features of lung metastases from pancreatic adenocarcinoma: Correlation with histopathologic findings

PURPOSE

The purpose of this study was to evaluate the prevalence of an atypical, alveolar presentation of pulmonary metastases from pancreatic adenocarcinoma (PDAC) on computed tomography (CT) and to correlate CT features with those obtained at histopathologic analysis.

MATERIAL AND METHODS

A total of 76 patients with lung metastases from PDAC over a 10-year period (2009-2019) in a French university hospital were retrospectively included. There were 34 men and 42 women with a mean age of 67.6±11.3 (SD) years (range: 38-89 years). CT features of PDAC were classified according to their presentations as usual metastatic pattern or atypical alveolar pattern; the atypical alveolar pattern corresponding to either ground glass nodules or opacities, solid nodules with a halo sign, "air-space" nodules with air bronchogram, or parenchymal consolidation. Imaging-histopathologic correlation was performed when tissue samples were available.

RESULTS

Pulmonary metastases were synchronous in 36 patients (36/76; 47%) and metachronous in 40 patients (40/76; 53%). A predominant alveolar presentation on CT was observed in 17 patients (17/76, 22%). Nodules with halo sign were the predominant alveolar pattern in 7 patients (7/17; 41%), air-space nodules were predominant in 4 patients (4/17; 24%) whereas pure ground glass nodules and consolidations were observed as predominant features in 3 patients (3/17; 18%) each. For 5 patients who had histopathological confirmation, alveolar metastases of PDAC were characterized by columnar tumor cells lining the alveolar wall, which was not seen in other radiological presentations, whereas there were no differences regarding mucin secretion between pulmonary metastases with alveolar presentation and those with typical pattern.

CONCLUSIONS

Lung metastases from PDAC may present with a so-called "alveolar" pattern on CT. This misleading CT features is found in 22% of patients with lung metastases from PDAC and is due to lepidic growth of the metastatic cells.

Metastatic pancreatic carcinoma masquerading as cystic lung disease: a rare presentation

This 52‐year‐old male ex‐smoker presented with a six‐month history of progressive breathlessness and weight loss. He deteriorated acutely, and was admitted with severe type 1 respiratory failure. Apart from diffuse coarse crackles on chest auscultation, physical examination was unremarkable. High‐resolution computed tomography (HRCT) showed diffuse cystic changes throughout the lungs. A diagnosis of pulmonary Langerhans cell histiocytosis (PLCH) was considered. Further workup identified a coincidental pancreatic lesion of uncertain significance, which remained indeterminate on magnetic resonance imaging (MRI) and on positron emission tomography (PET). Transbronchial biopsy revealed enteric differentiated adenocarcinoma exhibiting lepidic spread, and autopsy later confirmed primary pancreatic malignancy. This case demonstrates that metastatic pancreatic malignancy can present with severe respiratory failure and masquerade as cystic lung disease.