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SEER Inquiry System - Report
Produced: 11/01/2025 2:43 AM
Question 20240022
Inquiry Details
References:
#1: Solid Tumor Rules. multiple sites
#2: WHO Classifcation of Tumors
Question:
Solid Tumor Rules/Histology: When should the designation of “poorly differentiated” be used to further specify histology for carcinoma, NOS (8010) as undifferentiated carcinoma (8020)? See Discussion.
Discussion:
The term “poorly differentiated carcinoma (NOS)” is listed as related to “undifferentiated carcinoma (NOS)” in the ICD-O 3.2. It is also listed in the Solid Tumor Rules for Urinary Table 2 (Urinary subtypes), Other Sites Table 16 (uterine corpus primaries) and Table 19 (vulvar primaries).
Are these the only sites in which one should code “poorly differentiated carcinoma (NOS)” as 8020 (undifferentiated carcinoma)?
How is histology coded if the only microscopic confirmation is from a metastatic site showing “poorly differentiated carcinoma” (NOS) or “invasive carcinoma, poorly differentiated” (NOS)?
Example 1: Primary pancreatic cancer diagnosed on imaging and confirmed with liver mets core biopsy showing “poorly differentiated carcinoma.” Immunostaining pattern was non-specific. No further workup or treatment was planned.
Other Sites - Table 11 (Pancreas Histologies) includes undifferentiated carcinoma (8020/3) as a valid histology; however, the synonyms/subtypes/variants do not mention poorly differentiated carcinoma. How should histology be coded for this case?
Example 2: Hemicolectomy with cecal tumor final diagnosis of “invasive carcinoma, poorly differentiated” and synoptic summary listing “Histologic type: Invasive carcinoma. Histologic grade: G3 of 4: poorly differentiated.”
Colorectal Table 1 (Specific Histologies and Subtypes/Variants) includes undifferentiated adenocarcinoma/carcinoma 8020 as a subtype of adenocarcinoma NOS. There is no mention of poorly differentiated in this context. How should histology be coded for this case?
Answer:
Assign code 8020/3 when the histologic type specifically includes the term of poorly differentiated, dedifferentiated, undifferentiated, or anaplastic undifferentiated carcinoma along with carcinoma as terms vary depending on the primary site. When the term poorly differentiated is included in the grade section only of the pathology report or only mentions poorly differentiated carcinoma without further substantiation from a pathology report as in examples 1 and 2, do not use code 8020/3.
The histology code 8020/3 and terms may be used for selected primary sites as included in the Solid Tumor Rules, WHO Classification of Tumors series (latest versions), and the Site/Morphology Validation List including
Nasal cavity
Nasopharynx
Salivary glands
Urinary sites
Colon, rectosigmoid, rectum
Esophagus
Stomach
Gallbladder and extrahepatic bile duct
Pancreas
Thyroid
Ovary
Uterine corpus
Vagina
Uterine cervix (also referred to as unclassifiable in WHO Classification of Female Genital Tumors, 5th ed.)
For sites other than those listed, if the diagnosis is poorly differentiated carcinoma, code 8010/3 and poorly differentiated in the grade field.
