LOINCActive
LOINC Code 21996-4: Histology override flag Cancer case
21996-4 is a LOINC code used to identify Histology override flag Cancer case in laboratory and clinical observation data. You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges. LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Histology override flag. It is commonly used with the system or sample type Cancer case.XXX.
Reviewed by HealthAssure Clinical TeamUpdated 21 May 2026
What is this code?
LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Histology override flag. It is commonly used with the system or sample type Cancer case.XXX.
When is it used?
- Used in lab systems, EHRs, and clinical data exchange.
- May identify a test, observation, survey item, or clinical document request rather than a diagnosis.
- Status: ACTIVE
What it does not mean
- The code identifies the observation or test, not the actual result.
Key facts
Histology override flag Cancer case
Histology override flag
Some computer edits identify errors. Others indicate possible errors that require manual review for resolution. To eliminate the need to review the same cases repeatedly, over-ride flags have been developed to indicate that data in a record (or records) have been reviewed and, while unusual, are correct. This over-ride is used with the following edits in the NAACCR Metafile of the EDITS softwareDiagnostic Confirmation, Behavior Code (COC) Diagnostic Confirmation, Behavior Code (SEER IF31) Diagnostic Confirmation, Behavior ICDO3 (COC) Diagnostic Confirmation, Behavior ICDO3 (SEER IF31) Morph (1973-91) ICD-O-1 (SEER MORPH) Morphology--Type/Behavior (COC) Morphology--Type/Behavior (SEER MORPH) Morphology--Type/Behavior ICDO3 (COC) Morphology--Type/Behavior ICDO3 (SEER MORPH) Some edits check for code combinations that are possible, but quite rare. If the code combination generates an error message and review of the case indicates that the codes are correct for the case, then the over-ride flag is used to skip the edit in the future. See Chapter IV, Recommended Data Edits and Software Coordination of Standards. Over-ride Flags as Used in the EDITS Software Package Edits of the type Diagnostic Confirmation, Behavior Code differ in the use of ICD-O-2 or ICD-O-3 and check that, for in situ cases (Behavior = 2), Diagnostic Confirmation specifies microscopic confirmation (1, 2, or 4). The distinction between in situ and invasive is very important to a registry, since prognosis is so different. Since the determination that a neoplasm has not invaded surrounding tissues, i.e., in situ, is made microscopically, cases coded in situ in behavior should have a microscopic confirmation code. However, very rarely, a physician will designate a case noninvasive or in situ without microscopic evidence. If an edit of the type, Diagnostic Confirmation, Behavior Code, gives an error message or warning, check that Behavior and Diagnostic Confirmation have been coded correctly. Check carefully for any cytologic or histologic evidence that may have been missed in coding. The following histologies are not accepted as in situ: 8000-8005, 8020, 8021, 8331, 8320, 8800-9055, 9062, 9082, 9083, 9110-9493, 9501-9989. Edits of the type, Morphology--Type/Behavior, perform the following check: Codes listed in ICD-O-2 or ICD-O-3 with behavior codes of only 0 or 1 are considered valid, since the behavior matrix of ICD-O-2 and ICD-O-3 allows for the elevation of the behavior of such histologies when the tumor is in situ or malignant. This edit forces review of these rare cases to verify that they are indeed in situ or malignant. If a Morphology-Type/Behavior edit produces an error or warning message and the case is one in which the 4-digit morphology code is one that appears in ICD-O-2 or ICD-O-3 only with behavior codes of 0 or 1, verify the coding of morphology and that the behavior should be coded malignant or in situ. The registrar may need to consult a pathologist or medical advisor in problem cases. Exceptions: If year of Date of Diagnosis > 2000, then a behavior code of 1 is valid for the following ICD-O-2 histologies and no over-ride flag is needed: 8931, 9393, 9538, 9950, 9960-9962, 9980-9984, and 9989. Similarly, the following ICD-O-3 histologies are valid with a behavior code of 1: 8442, 8451, 8462, 8472, and 8473. If year of Date of Diagnosis > 2003, the following ICD-O-3 benign histologies will pass without review: 8146, 8271, 8861, 8897, 9121, 9122, 9131, 9161, 9350, 9351, 9352, 9360, 9361, 9383, 9384, 9394, 9412, 9413, 9444, 9492, 9493, 9506, 9531, 9532, 9533, 9534, 9537, 9541, 9550, 9562, and 9570. Grade 5-8 with histologies not in the rage of 9590-9948 is impossible. Instructions for Coding Leave blank if the program does not generate an error message for the edits of the types, Diagnostic Confirmation, Behav Code or Morphology--Type/Behavior. Leave blank and correct any errors for the case if an item is discovered to be incorrect. Code 1, 2, or 3 as indicated if review of all items (Diagnostic Confirmation, Behavior, and Morphology) in the error or warning message confirms that all are correct... NAACCR Data Standards and Data Dictionary Version 11
Arbitrary; CA; Histology O/R; Misc; Miscellaneous; Oncology; Ordinal; Other; Point in time; QL; Qual; Qualitative; Random; Screen; Spec; To be specified in another part of the message; TUMOR REGISTRY(NAACCR); Unspecified
Where you may see this code
You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges.
Common synonyms
Histology override flag Cancer caseHistology O/R Cancer caseHistology override flagTUMRRGTArbPtCancer case.XXX
Frequently asked questions
About this content
This page is prepared by HealthAssure's clinical team using official coding standards from LOINC. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.