Aims: To describe two cases of localised malignant mesothelioma with a predominantly intrapulmonary growth which led to a pre-operative diagnosis of pulmonary carcinoma.
Materials and methods: Both cases presented as intrapulmonary masses, while at computed tomography scan the pleura appeared not significantly thickened. In one patient, the main bronchus was diffusely infiltrated by the tumour. In both cases, a preoperative biopsy showed a proliferation of large cells leading to a diagnosis of non-small-cell lung carcinoma. Histological examination of the surgical specimens revealed features consistent with epithelioid mesothelioma with deciduoid features in one case and with biphasic mesothelioma in the other. Both cases were diffusely positive with anti-calretinin antibody, while anti-TTF1, anti-surfactant and anti-CEA antisera were negative.
Conclusions: Localised malignant mesotheliomas are unusual and predominantly intrapulmonary growth is rare. Pathologists should be aware of this possibility to avoid misdiagnosis, particularly in small biopsies.