Malignant Mesothelioma in Situ Diagnosed by Methylthioadenosine Phosphorylase Loss and Homozygous Deletion of CDKN2A: A Case Report

Virchows Arch. 2020 Mar;476(3):469-473. doi: 10.1007/s00428-019-02674-x. Epub 2019 Oct 30.


Malignant pleural mesothelioma (MPM), associated with unfavorable outcomes, is closely associated with asbestos exposure. Early detection and treatment are critical to prolong survival of patients with MPM because of the rapid progression and resistance to treatment. The recently defined malignant mesothelioma in situ (MIS) has been gaining increasing attention with advances in genome-based methods including fluorescence in situ hybridization (FISH) as well as immunohistochemistry. We herein report the case of a MIS in a 73-year-old male with a history of asbestos exposure presenting with massive pleural effusion in the right thoracic cavity. Video-assisted thoracoscopic surgery with pleural biopsy of the right side revealed a single layer of atypical mesothelial cells without invasive lesions by hematoxylin and eosin staining. However, these mesothelial cells exhibited a loss of methylthioadenosine phosphorylase (MTAP) by immunohistochemistry and homozygous deletion of CDKN2A (p16) by FISH, leading to the diagnosis of MIS.

Keywords: Fluorescence in situ hybridization; Homozygous deletion of CDKN2A (p16); Immunohistochemistry; Malignant mesothelioma in situ; Methylthioadenosine phosphorylase.

Publication types

  • Case Reports

MeSH terms

  • Aged
  • Biomarkers, Tumor / analysis*
  • Cyclin-Dependent Kinase Inhibitor p16 / analysis
  • Cyclin-Dependent Kinase Inhibitor p16 / genetics
  • Early Diagnosis*
  • Genes, p16
  • Humans
  • Lung Neoplasms / diagnosis*
  • Male
  • Mesothelioma / diagnosis*
  • Pleural Neoplasms / diagnosis*
  • Purine-Nucleoside Phosphorylase / analysis
  • Purine-Nucleoside Phosphorylase / biosynthesis
  • Sequence Deletion


  • Biomarkers, Tumor
  • CDKN2A protein, human
  • Cyclin-Dependent Kinase Inhibitor p16
  • Purine-Nucleoside Phosphorylase
  • 5'-methylthioadenosine phosphorylase

Supplementary concepts

  • Mesothelioma, Malignant