Ontology patterns for tubular or spherical layered structures. A case study from oncology

The TNM classification supports malignant tumour staging and classification, based on size and location. The ontology framework TNM-O was recently proposed as a formal-ontological foundation of TNM. A number of gastrointestinal tumours have similar rules for classification, dependent on the anatomical layers of the wall of the digestive tract the tumour invades into. In this paper we propose a generalized pattern to represent spatial relations between the layers of tubular or spherical structures in anatomy. Using this pattern, we can create a strict total order on the layers, which proves useful for reasoning about the location of entities like tumours that spread across gastro-intestinal wall structures.