> For the complete documentation index, see [llms.txt](https://docs.snomed.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.snomed.org/education/snomed-ct-education-editorial-guide/readme/authoring/domain-specific-modeling/body-structure/index-2/lump-and-mass.md).

# Lump and mass

<mark style="color:$danger;">**This Editorial Guide is used for Education Purposes Only. It is used in the Authoring Courses and Certifications. It is based on the January 2026 Editorial Guide.**</mark>

Distinguishing consistently between lump and mass can be difficult in diagnostic contexts, as the terms are often used interchangeably or lack precise definitions. As a result, lump and mass have, in certain conditions, been treated as synonymous.

Avoid using 'lump' in new content, where more specific terminology is available.

Lump should not be added as a synonym for mass concepts in the Finding or Disorder hierarchies. Existing legacy synonyms and concepts will remain unchanged.

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