How does the Kiupel scheme separate low from high grade MCTs?

How does the Kiupel scheme separate low from high grade MCTs?

• A. Tumor size
• B. Mitotic count, presence of multinucleated cells, bizarre nuclei, and/or karyomegaly
• C. Histologic age
• D. Mitotic figures only

Answer: (B)

Kiupel’s two-tier grading relies on what the tumor cells look like and how actively they’re dividing, not on how big the tumor is or the patient’s age. High-grade MCTs are identified by the presence of certain cellular features that reflect aggressive biology: a high mitotic count and/or abnormal nuclear features such as multinucleation, bizarre (atypical) nuclei, or karyomegaly. If these cytologic characteristics are not present, the tumor is considered low grade. This focus on cellular morphology and mitotic activity aligns with prognosis, since tumors showing these features tend to behave more aggressively.

Kiupel’s two-tier grading relies on what the tumor cells look like and how actively they’re dividing, not on how big the tumor is or the patient’s age. High-grade MCTs are identified by the presence of certain cellular features that reflect aggressive biology: a high mitotic count and/or abnormal nuclear features such as multinucleation, bizarre (atypical) nuclei, or karyomegaly. If these cytologic characteristics are not present, the tumor is considered low grade. This focus on cellular morphology and mitotic activity aligns with prognosis, since tumors showing these features tend to behave more aggressively.