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We would like to confirm that the correct histology code is 9431/1 per ICD-O-3.2, as the Non-Malignant CNS Solid Tumor Manual lists the histology code as both 9431/1 (pages 301 and 303 of the combined manual), but also shows it as a synonym for 9421/1 – Diffuse astrocytoma, MYB- or MYBL1 altered (page 304).

Patient has a 3 cm tumor in the temporal lobe of the brain. This was noted on MRI 12/2022. The radiologist states this is a low-grade glioma and recommends following with routine scans. No pathology or resection performed or planned. Patient has been followed with imaging every six months with stable disease. Low grade glioma is not currently listed in ICD-O-3.2 or the current Solid Tumor Rules. What histology should be assigned to the case?

The patient has a history of ganglioglioma, WHO grade I, involving the deep right parietal lobe diagnosed on resection in 07/2012. Tumor recurrence in 2017 was treated with radiation.

The patient then had right temporal tumor biopsy and resection 06/2021 with final diagnosis of anaplastic glioneuronal tumor, BRAF p.V600E mutant, WHO Grade III. Pathologist notes that the tumor demonstrates a ganglioglioma with frequent mitoses and possible vascular proliferation. Subsequent consult findings support an anaplastic glioneuronal tumor, compatible with progression of the patient's ganglioglioma that is post-irradiation. However, the pleomorphic and epithelioid areas are also reminiscent of pleomorphic xanthoastrocytoma, which may occur in combination with ganglion cell components. There is no related SINQ to code this histology.

In the NAACCR Coding Pitfalls 2023 webinar, the example of DCIS, solid type is given. The webinar advised us to code 8230/2 (ductal carcinoma in situ, solid type). When going through the beginning of the solid tumor rules in the Changes from 2007 MPH Rules section it states "DCIS/Carcinoma NST in situ has a major classification change. Subtypes/variant, architecture, pattern, and features ARE NOT CODED. The majority of in situ tumors will be coded to DCIS 8500/2." In the equivalent or equal terms section it lists "Type, subtype, variant" can be used interchangeably.

Since the example has it listed as as ductal carcinoma in situ, solid "type," would we code 8500/2 or 8230/2? 

Example: 12/2023 Breast lumpectomy final diagnosis is Invasive ductal carcinoma, lymphoepithelioma-like carcinoma type. This is a single tumor with no in situ carcinoma present.

Lymphoepithelioma-like carcinoma is not listed as a subtype/variant or synonym for breast carcinoma in the Solid Tumor Rules histology tables.

The Solid Tumor Rules indicate p16 is a valid test to determine HPV status and can be used to code HPV-associated/-independent.

In this case, we do not know whether the HR-HPV test was done on cytologically malignant cells, or on benign cervical cells. It may be impossible to tell unless 100% of the cytology specimen is malignant, but we will not have access to that information. Also, HR-HPV testing is routine on Pap smears, so this testing does not mean the tumor cells specifically harbor HPV.

Previous SINQ 20091100 has a similar scenario and the instruction was to code as lentigo maligna (8742/2); however, it does not appear to be applicable to cases diagnosed after 2020.

The WHO Blue Book does not list melanoma, lentiginous type or lentiginous melanoma in situ as an alternate term for lentigo maligna and neither do the STR or the ICD-O-3.2.

There was a single right fallopian tube tumor with two distinct morphologies. The diagnosis comment states, “The combined morphologic and immunohistochemical features are best classified as primary fallopian tube high grade serous carcinoma with a somatically derived yolk sac tumor.” 

Laryngeal intraepithelial neoplasia II-III is not included in the ICD-O-3.2 and, while the SEER Program Coding and Staging Manual (SPCSM) confirms this is reportable, neither the SPCSM nor the Solid Tumor Rules Manual provide the specific histology to use for LIN II or LIN III. Should this be coded as 8077/2 since this is most like a high grade squamous dysplasia?

There are two histologies provided in the final diagnosis, malignant spindle cell neoplasm (8004/3) and atypical fibroxanthoma (8830/3). There is a definitive diagnosis of the non-specific histology, but the more specific histology is only described using ambiguous terminology.

The external ear (C442) is included in the Head and Neck schema for diagnosis year 2018 and later. The Head and Neck Histology Rules indicate ambiguous terminology cannot be used to code a more specific histology. So ignoring the atypical fibroxanthoma, because it is modified by ambiguous terminology, we are left with a non-reportable site and histology combination (C442, 8004/3).

Diagnoses of malignant atypical fibroxanthomas are regularly diagnosed using the syntax above in our area. Follow-up with the physician or pathologist is generally not possible as these cases are received from dermatopathology clinics only. The pathology report is the only information that will be received. If the reportable diagnosis of malignant atypical fibroxanthoma is ignored per the current Solid Tumor Rules, incidence cases will be lost.