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2 mm Size Rule of Tavassoli for Ductal Carcinoma in Situ (DCIS)

Description

Tavassoli proposed a rule based on the size of histologic focus of an atypical ductal proliferation that could aid in the distinction between atypical ductal hyperplasia (ADH) and ductal carcinoma in situ (DCIS). While somewhat arbitrary, the rule based upon the author's consultation practice. The author is from the Armed Forces Institute of Pathology (AFIP) in Washington, DC.


 

The histologic examination involves the terminal duct/lobular unit (TDLU).

 

The diameters of all foci of atypical ductal epithelial proliferation in the TDLU are measured.

 

aggregate diameter in mm =

= SUM(diameters of all foci of atypical ductal epithelial proliferation)

 

Aggregate Diameter

Interpretation

< 2.0 mm

ADH

>= 2.0 mm

DCIS

 

Additional guidance:

(1) The rule applies only to nonnecrotic atypical intraductal proliferations compatible with low grade DCIS.

(2) A high grade intraductal proliferation with or without necrosis should be diagnosed as DCIS no matter the size.

 


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Specialty

ICD-10