American Board of Internal Medicine (ABIM) Certification Practice Exam

Patients with which type of MGUS can follow up once every 2 to 3 years if stable?

1. IgA MGUS

2. IgM MGUS

3. IgG MGUS

4. Non-IgG MGUS

The correct answer is: IgG MGUS

In the context of monoclonal gammopathy of undetermined significance (MGUS), it is well-established that patients with IgG MGUS can follow up every 2 to 3 years if they remain stable. This type of MGUS is the most common and typically has a low risk of progression to multiple myeloma or other related malignancies compared to the other types. IgG MGUS is associated with a stable clinical course in a majority of cases, allowing for a less frequent monitoring schedule. The rationale behind less frequent follow-up is rooted in studies that have shown that patients with this subtype have a much lower risk (approximately 1% per year) of progressing to hematologic malignancies. In contrast, other types of MGUS, such as IgM and non-IgG variants, often require more frequent monitoring. IgM MGUS, for instance, carries a higher risk of transformation to Waldenström's macroglobulinemia and demands closer surveillance. Non-IgG subtypes can also demonstrate a range of risks for progression, necessitating tighter follow-up schedules. Overall, the established clinical guidelines emphasize the safe follow-up duration for IgG MGUS, reflecting its typically favorable prognosis and stability for patients who remain symptomatically