Transient monoclonal gammopathy in a 2-year-old child with combined viral and bacterial infection

Prognosis of young patients with monoclonal gammopathy of undetermined significance (MGUS)

Monoclonal gammopathy of undetermined significance (MGUS) is rare in young patients (age <40 years at diagnosis), with a prevalence of <0.3%, representing ~2% of all patients with MGUS. We hypothesized that MGUS detected in young patients may be associated with a higher risk of progression. We examined 249 patients with MGUS < 40 years old. Among these, 135 patients had immune-related conditions, including infections, autoimmune and inflammatory disorders at the time of diagnosis of MGUS. The risk of progression to multiple myeloma or a related disorder at 5 years and 10 years was 6.0% and 13.8%, respectively. The size of M protein was a significant risk factor for progression (HR 4.2, 95% CI 2.2–7.9). There was a trend that the risk of progression was higher in patients without immune-related conditions (HR 2.36, 95% CI 0.85–6.52, p = 0.088). The M protein resolved in 36 (14%) patients, with a greater likelihood of resolution in patients with immune-related conditions (RR 1.9, 95% CI 1.02–3.6). Young patients with MGUS have a similar risk of progression as older patients, 1.4% per year. Over 50% are diagnosed in the setting of immune-related disorders. Patients with immune-related disorders may have a lower risk of progression.