Embryological Origin of Malignant Mesothelioma
The correct answer is C) Lateral plate mesoderm, as malignant mesothelioma arises from mesothelial cells that line the pleural, peritoneal, and pericardial cavities, which are derived from the lateral plate mesoderm during embryonic development.
Cellular Origin and Embryology
Malignant mesothelioma is a neoplasm arising from mesothelial cells that line the serous cavities including the pleura, peritoneum, and pericardium 1, 2. The mesothelium represents specialized mesoderm with an epithelial-like arrangement that persists from embryological development 3.
The mesothelial lining of serous cavities originates from the lateral plate mesoderm, which during embryonic development splits into somatic (parietal) and splanchnic (visceral) layers, creating the coelomic cavities 3. This mesodermal origin explains the cellular variability and multipotential differentiation capacity seen in mesotheliomas 3.
Why Other Options Are Incorrect
Paraxial mesoderm (Option A): This gives rise to somites, which form skeletal muscle, vertebrae, and dermis—not serous membranes 3
Intermediate mesoderm (Option B): This forms the urogenital system including kidneys and gonads, not the pleural lining 3
Endoderm (Option D): This forms the epithelial lining of the gastrointestinal and respiratory tracts, not the mesothelial surfaces 3
Clinical Relevance
Understanding the mesodermal origin is important because it explains why mesotheliomas can exhibit diverse histological patterns—epithelioid, sarcomatoid, and biphasic subtypes—reflecting the multipotential nature of their mesodermal precursor cells 1. The undifferentiated mesoderm in neoplastic disease exhibits a wide range of differential activity, giving rise to tumors with myoblastic, fibroblastic, or epithelial-like features 3.
The diagnosis requires immunohistochemical confirmation of mesothelial lineage using markers such as calretinin, cytokeratin 5/6, WT1, and podoplanin (D2-40), which help distinguish mesothelioma from adenocarcinomas and other malignancies 1.