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SEER Inquiry System - Report
Produced: 03/29/2026 2:12 PM
Question 20210078
Inquiry Details
References:
#1: 2007 Solid Tumor Rules. Other Sites; September 2021 Update
#2: WHO Class Skin Tumors, 211-212
Question:
Solid Tumor Rules (2018/2021)/Multiple Primaries--Skin Cancer: How many primaries are assigned for sebaceous carcinomas using the Solid Tumor/Multiple Primaries/Histology Rules? Does this scenario represent eight separate primaries? See Discussion.
Discussion:
Details
4/15/2018: Right abdominal wall mass excision: infiltrating sebaceous carcinoma. Noted to have a history of Muir-Torre/Lynch syndrome.
1/21/2019: Two left upper back mass excisions and two lower back (laterality not specified) mass excisions: infiltrating sebaceous carcinomas
8/7/2019: Excision of multiple sebaceous carcinomas from the right posterior back, left posterior thigh, left anterior abdominal wall, left anterior thigh, right scrotum, right lower abdominal fold, all positive for sebaceous carcinoma on pathology report
9/30/2020: Right gluteal mass, left gluteal mass, back (NOS) excisions: sebaceous carcinomas.
10/14/2020: Right back excision: sebaceous carcinoma. Op note: History of Lynch syndrome with multiple sebaceous carcinomas, recurrent back mass, site of prior mass resection.
10/18/2021: Right thigh excision: sebaceous carcinoma
Proposed primaries using MP/H Other Sites Rules
#1: 4/15/2018: C445-1
#2: 1/21/2019: C445-2, separate from #1 per M8, same as 1/21/19 C445-9 per M18
#3: 8/7/2019: C445-1, separate from #1 per M10, separate from #2 per M8
#4: 8/7/2019: C447-2, separate from #1 & #3 per M8, separate from #2 per M12
#5: 8/7/2019: C632, separate from #1 per M10, separate from #2-#4 per M11
#6: 9/30/2020: C445-2, separate from #1 & #3 per M8, separate from #2, #4 & #5 per M10
#7: 9/30/2020: C445-1, separate from #2, #4 & #6 per M8, separate from #1, #3 & #5 per M10; I do not think the back, NOS (C445-9) is a new primary per M18.
#8: 10/18/2021: C447-1, separate from #2, #4 & #6 per M8, separate from #1, #3, #5 & #7 per M10
Answer:
Assign the number of primaries following the Other Sites Solid Tumor Rules. Based on sites, laterality and or timing there are 8 primaries. This is similar to SINQ 20061112 that advised to follow the Multiple Primaries/Histology rules for sebaceous carcinoma. According to the WHO Classification of Skin Tumors, 5th edition, there is a 30-40% risk of local tumor recurrence, and 20-25% risk of distant metastasis. In only one instance did a physician refer this as a recurrence in the available notes.
