SEER Inquiry System - Question 20150027 Details

Pathologists rarely diagnose a GIST as a malignant tumor. Per the AJCC, GISTs encompass a continuum in terms of biologic potential, with larger more mitotically active tumors landing on the "histologically sarcomatous" or malignant end of the spectrum. Because the pathologists generally do not categorize these tumors as benign or malignant, the judgement is typically made by the clinician in light of all the clinical and pathologic findings. Unless there are obvious distant metastases, the clinician usually decides whether a GIST is malignant and treats the patient as such.

In the case above, the patient underwent a gastric biopsy on 04/10/2014 that showed GIST. The subsequent resection on 04/12/2014 showed a 4.5 cm GIST, spindle cell type with 6 mitoses/5 square mm. The resection pathology report does not indicate the GIST is malignant, but does identify a large tumor with mitotic activity. After reviewing the evidence in this case, the clinician calls this a malignant GIST on 04/29/2014 and starts the patient on Gleevec.

Although neither the biopsy nor the resection call this a malignant tumor, should the date the GIST was first diagnosed (biopsy on 04/10/2014) be used to code the diagnosis date, since this is the date the tumor (ultimately felt to be malignant) was diagnosed? If the diagnosis date is coded as the date malignant GIST was first mentioned (04/29/2014), this would exclude surgery as treatment for this tumor.

Would this be a histologic diagnosis because the tumor was histologically confirmed to be GIST? Or must this be a clinical diagnosis because the diagnosis of malignancy was only made clinically (by the clinician's review of the clinical and pathologic findings)?