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Updated: Aug 12, 2026
Orthotopic Implantation and Peripheral Immune Cell Monitoring in the II-45 Syngeneic Rat Mesothelioma Model
Published on: October 2, 2015
The pathology associated with therapeutic procedures in malignant mesothelioma
1Department of Histopathology, Cardiff and Vale NHS Trust, Llandough Hospital, Cardiff, UK.
Aims:
To describe iatrogenic pathological lesions in malignant pleural mesothelioma.
Methods And Results:
All cases of malignant pleural mesothelioma confirmed by antemortem pleural biopsy and undergoing post mortem examination over a 7-year period (1995-2001) formed the study group. This comprised 48 malignant pleural mesotheliomas [epithelioid (n = 21), biphasic (n = 14) and sarcomatoid (n = 13)]. Twenty-eight of 48 (58%) had received chemical (talc) pleurodesis, 30/48 (63%) palliative localized radiotherapy, 6/48 (13%) chemotherapy, and 14/48 (30%) surgery [12/48 (26%) pleural decortication and 2/48 (4%) pleuropneumonectomy].
Conclusions:
Talc pleurodesis induces a marked pseudosarcomatous fibroblastic proliferation which may impart a biphasic pattern to the neoplasm. In more chronic cases, paucicellular fibrosis with a foreign body giant cell reaction is noted. The talc is polarizable and deposited in linear fashion within the tumour. In 2/28 (7%) pleurodesis cases platyform ferruginous bodies were seen in the peripheral alveolated lung parenchyma and these mimicked asbestos bodies. An awareness of this is important to prevent false attribution to asbestos. Talc could be identified by transmission electron microscopic mineral analysis in 5/15 (33%) cases examined. Tumour nodules developing subjacent to iatrogenic wound sites were noted in 8/48 (17%) cases. In 6/8 (75%) of these cases, comparative assessment of the locally irradiated subcutaneous chest wall tumour, with background pleural mesothelioma, showed no morphological difference in architectural tumour growth pattern, extent of necrosis, cytological or nuclear pleomorphism, mitotic activity or tumour immunophenotype. In 2/8 (25%) cases the locally irradiated tumour showed prominent bizarre multinucleated tumour giant cells and intense mixed inflammation, a feature not seen in the background (non-irradiated) tumour. All six malignant pleural mesotheliomas receiving chemotherapy appeared refractory to treatment in that chemotherapy did not appear to have any significant effect on the tumour morphology, cytonuclear pleomorphism, mitotic activity, extent of necrosis or immunophenotype. In the 12 decortication specimens and two pleuropneumonectomy resections, post mortem examination identified evidence of residual malignant mesothelioma of similar morphological subtype and immunophenotype to the resected tumour.
Insights
Iatrogenic interventions like talc pleurodesis can cause pseudosarcomatous changes in malignant pleural mesothelioma, mimicking asbestos exposure. Tumor nodules at wound sites may show similar or altered morphology after radiation.
Area of Science:
- Pathology
- Oncology
- Pulmonology
Background:
- Malignant pleural mesothelioma is a rare and aggressive cancer.
- Iatrogenic interventions are common in managing malignant pleural mesothelioma.
Purpose of the Study:
- To describe pathological lesions resulting from iatrogenic interventions in malignant pleural mesothelioma.
- To differentiate treatment-induced changes from intrinsic tumor features.
Main Methods:
- Post-mortem examination of 48 malignant pleural mesothelioma cases over 7 years.
- Analysis of lesions following talc pleurodesis, radiotherapy, chemotherapy, and surgery.
Main Results:
- Talc pleurodesis induced pseudosarcomatous proliferation and, rarely, ferruginous bodies mimicking asbestos.
- Tumor nodules at wound sites showed varied responses to radiotherapy.
- Chemotherapy did not significantly alter tumor morphology or immunophenotype.
Conclusions:
- Iatrogenic interventions can create pathological changes that may be misinterpreted.
- Awareness of these changes is crucial for accurate diagnosis and avoiding misattribution to asbestos.
- Radiotherapy can induce specific changes in iatrogenic tumor nodules.
