Pathology/Lab Coding Alert

Question: How should I code a left ovary struma ovarii if the pathologist notes that the tumor “demonstrates an unusual presentation, including extensive mitosis and pleiomorphisms consistent with malignant changes.”?

Iowa Subscriber

Answer: The correct code would be C56.2 (Malignant neoplasm of left ovary).

If you look up “struma ovarii” in the ICD-10 alphabetic index, as you should, you’ll be directed to D27.1 (Benign neoplasm of left ovary), which may be confusing given the pathologist’s statement of malignancy.

But recall that if the pathology report identifies the cancer behavior, that’s what you should code. The pathologist’s determination overrides a “typical” behavior for a certain type of cancer.

While it is true that this rare tumor (which involves growth of thyroid tissue in the ovary) is typically benign, malignant changes can take place. In this case, the pathologist identifies those malignant changes, and that’s what you should code.