In the July 2018 update, there was a wording change to Breast M11 (previously M10)
Current wording:
Rule M11 Abstract a single primaryi when a ductal carcinoma occurs after a combination code in the same breast. See the following list:
• DCIS following a diagnosis of:
ο DCIS + lobular carcinoma in situ 8522/2 OR
ο DCIS + in situ Paget 8543/2 OR
ο DCIS + Invasive Paget 8543/3 OR
ο DCIS mixed with other in situ 8523/2 (code used for cases diagnosed prior to 1/1/2018)
Old wording: (previously M10)
Abstract a single primaryi when any of the following conditions are met in the same breast:
• DCIS subsequent to a diagnosis of mixed DCIS AND:
ο Lobular carcinoma in situ 8522/2 OR
ο In situ Paget 8543/2 OR
ο Invasive Paget 8543/3 OR
ο Other in situ 8500/2 (prior to 2018, DCIS and other in situ was coded 8523/2)
• Invasive carcinoma NST/duct subsequent to a diagnosis of mixed invasive carcinoma
The other issue is 8500/2. It's not a combination code so it should be removed from the rule, and then cases of 8500 following 8500 of any behavior will hit the last resort rule. Either way it will be a single primary but then at least it will match what humans are doing.
In the July 2018 update, there was a wording change to Breast M11 (previously M10)
Current wording: Rule M11 Abstract a single primaryi when a ductal carcinoma occurs after a combination code in the same breast. See the following list: • DCIS following a diagnosis of: ο DCIS + lobular carcinoma in situ 8522/2 OR ο DCIS + in situ Paget 8543/2 OR ο DCIS + Invasive Paget 8543/3 OR ο DCIS mixed with other in situ 8523/2 (code used for cases diagnosed prior to 1/1/2018)
Old wording: (previously M10) Abstract a single primaryi when any of the following conditions are met in the same breast: • DCIS subsequent to a diagnosis of mixed DCIS AND: ο Lobular carcinoma in situ 8522/2 OR ο In situ Paget 8543/2 OR ο Invasive Paget 8543/3 OR ο Other in situ 8500/2 (prior to 2018, DCIS and other in situ was coded 8523/2) • Invasive carcinoma NST/duct subsequent to a diagnosis of mixed invasive carcinoma
The other issue is 8500/2. It's not a combination code so it should be removed from the rule, and then cases of 8500 following 8500 of any behavior will hit the last resort rule. Either way it will be a single primary but then at least it will match what humans are doing.