Tract metastasis in patients with long-term pleural catheter-computed tomography diagnosis and longitudinal assessment

Our plain-English summary of Tract metastasis in patients with long-term pleural catheter-computed tomography diagnosis and longitudinal assessment, by F. Hamad, C. Souza, M. Mitchell, et al (European Radiology, 2021).

The study

• Authors: F. Hamad, C. Souza, M. Mitchell, K. Amjadi
• Journal: European Radiology
• Published: 2021;31(10):7325-7331
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: Long-term indwelling pleural catheters (IPC), used for the management of malignant pleural mesothelioma (MPM), may lead to catheter tract metastasis (CTM). While computed tomography (CT) is valuable for diagnosis, no studies have assessed CT manifestations of CTM. Our goal is to describe the incidence, CT appearances, and temporal evolution of CTM in MPM.

Methods: A retrospective review of CT of 90 consecutive patients with MPM and IPC. In patients with CTM, a longitudinal assessment was performed for CT appearance at diagnosis and over time, interval from insertion to diagnosis and rate of progression.

Results: The incidence of CTM was 26% (23/90), in 22 men (54-83 years, mean 73 years). CTM manifested with focal lesion (3 to 60 mm, mean 25 mm) in the subcutaneous tissue at the insertion site. Abnormalities of sub-adjacent skin and fat stranding were present in 16/24 (66%) and 11/24 (46%), respectively, enlargement of chest wall musculature in 11/24 (46%), and dilated subcutaneous vessels in 4/24 (17%) patients. On follow-up, 53% had enlargement of focal lesion. The average rate of progression was 3.5 mm/month, compared to 0.79 mm/month for pleural thickening (p = 0.03). The time between IPC insertion and CTM diagnosis varied from 58 to 1375 days (median 408 days); 83% occurred after IPC removal. Reporting radiologists described focal abnormality at the insertion site in only 9/23 (39%) patients.

Conclusions: CTM is commonly overlooked and underreported by radiologists. CT invariably demonstrates focal subcutaneous lesion in the procedure tract, most commonly after IPC removal. Ancillary findings, notably serratus or latissimus dorsi muscle enlargement, are novel finding that can assist in CT detection and diagnosis.

Key Points: • Catheter tract metastasis (CTM), resulting from indwelling pleural catheter to manage malignant pleural mesothelioma, invariably manifested on CT as a focal subcutaneous lesion at the site of insertion, more commonly after catheter removal. • Ipsilateral muscle enlargement is a newly described CT finding that can assist in the detection and diagnosis. • Catheter tract metastasis was commonly overlooked by radiologists, reported in only 39% of cases.

© 2021. European Society of Radiology.

In plain English

This retrospective study from one pleural disease clinic reviewed CT scans of 90 consecutive patients with biopsy-proven malignant pleural mesothelioma who had a long-term indwelling pleural catheter (a drainage tube). The patients were identified in a clinic database covering May 2006 to July 2017. The study looked for catheter tract metastasis, meaning tumor growing along the catheter's path. Of the 90 patients, 23 (26%) had it. It was diagnosed on CT 58 to 1375 days after insertion (median 408 days). In 19 of the 23 (83%) it was seen after the catheter had been removed. All 23 had a focal lesion under the skin, 3 to 60 mm across. Nearly half had enlarged nearby chest wall muscles. Of 17 patients with follow-up scans, 9 (53%) had lesion growth. Lesions grew an average of 3.5 mm per month, versus 0.79 mm per month for pleural thickening (p = 0.03). The original radiology reports described a site abnormality in only 9 of 23 cases (39%). The authors concluded the complication is commonly overlooked on CT. They noted the incidence may be overstated. Without tissue samples, the meaning of the accompanying findings was uncertain.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective review of CT scans at a single institution (an ad hoc analysis of a cohort used in an earlier published study)
• Who was studied: 90 patients with biopsy-proven malignant pleural mesothelioma who had an indwelling pleural catheter. They were identified from a database of over 1850 consecutive patients at a tertiary care pleural disease clinic. The database covered May 2006 to July 2017.
• Exposure: Long-term indwelling pleural catheter (PleurX) placed for pleural effusion. The article does not discuss asbestos or fiber types.
• Main results:
  • 23 of the 90 patients (26%) had catheter tract metastasis.
  • The interval from catheter insertion to CT diagnosis was 58 to 1375 days (median 408 days, IQR 196 to 721 days).
  • In 19 of the 23 cases (83%), the metastasis was seen on CT after catheter removal. In 4 cases (17%), it was adjacent to the catheter.
  • All 23 cases had a focal soft tissue lesion in the subcutaneous tissue of the chest wall. The lesions measured 3 to 60 mm (mean 25 mm).
  • The text reports several accompanying findings: skin abnormalities in 16/24 (66%), fat stranding in 11/24 (46%), and asymmetric enlargement of chest wall muscles (latissimus dorsi and serratus anterior) in 11/24 (46%).
  • Of 17 patients with follow-up CTs, 9 (53%) had enlargement of the lesion.
  • The lesions grew an average of 3.5 mm per month, compared with 0.79 mm per month for pleural thickening (p = 0.03).
  • The original reporting radiologists described an abnormality at the catheter site in 9 of the 23 cases (39%).
  • The incidence did not differ significantly between mesothelioma subtypes (p = 0.09).
• The authors' conclusion: The authors concluded that catheter tract metastasis is commonly overlooked on CT and underreported. They described it as a focal lesion under the skin along the catheter tract, often seen long after catheter removal. They also concluded that asymmetric chest wall muscle enlargement is a newly described finding that can assist detection.
• Limitations the authors state:
  • The incidence may be overstated because the referral center is in an area where mesothelioma is common.
  • Because diagnosis was based on CT, some included patients may have had clinically insignificant findings.
  • In a retrospective study, it was hard to tell whether reported pain was caused by the metastasis or something else.
  • There was no tissue diagnosis, so the meaning of the muscle enlargement and other accompanying findings is uncertain.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Tract Metastasis, Indwelling Pleural Catheter, Pleural Mesothelioma, Pleural Thickening.

Related studies

• Catheter Tract Metastasis in Mesothelioma Patients with Indwelling Pleural Catheters: A Retrospective Cohort Study — M.A. Mitchell, P. Li, et al. (2019)
• Catheter tract metastasis associated with indwelling pleural catheters — R. Thomas, C.A. Budgeon, et al. (2014)
• Pseudo-tumor mimicking indwelling pleural catheter tract metastasis in mesothelioma — R.L. Shrestha, B.A. Wood, et al. (2014)
• Diagnostic Value of Computed Tomography Imaging Features in Malignant Pleural Mesothelioma — M. Fortin, E. Cabon, et al. (2020)
• Intrapleural Fibrinolysis for the Treatment of Indwelling Pleural Catheter-Related Symptomatic Loculations: A Multicenter Observational Study — R. Thomas, F. Piccolo, et al. (2015)
• The use of indwelling pleural catheters for the management of malignant pleural effusion--direct costs in a Dutch hospital — R.C. Boshuizen, S. Onderwater, et al. (2013)

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