Criteria of Som for Lymph Node Metastasis on a CT Image

Description

Som listed criteria for metastases in cervical lymph nodes as seen on a CT scan. CT scan can identify more metastases than palpation alone and can evaluate nodes that are difficult to palpate. The author is from Mount Sinai School of Medicine, City University of New York.

Parameters:

(1) extranodal/extracapsular spread

(2) nodal shape

(3) nodal size (maximum nodal diameter)

(4) localized nodal grouping draining a tumor site

(5) central necrosis

Parameter	Features in Metastasis	False Positive
extranodal spread	poorly defined margins around node; contrast enhancement of nodal capsule	recent surgery, irradiation therapy, active infection
nodal shape	spherical	hyperplasia ("lima bean" like)
nodal size (maximum nodal diameter)	> 1.5 cm for jugulodigastric and submandibular groups; > 1.0 cm for all others
nodal size (minimum nodal diameter)	> 1.1 cm in jugulodigastric group; > 1.0 cm in others
nodal grouping	>= 3 contiguous and confluent nodes; minimum axial diameter 0.8 cm	tuberculosis
central necrosis	low attenuation in center; periphery thick, irregular and contrast enhancing	fatty metaplasia or infiltration; abscess

A good clinical history can often identify conditions that cause the false positives.

Limitations:

• The description is based on change in cervical lymph nodes. Many tumors of the head and neck are squamous cell carcinomas, so some of the features may reflect changes seen with this tumor type.

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Description

Specialty

ICD-10