Do you pursue a malignancy workup beyond age-appropriate malignancy screening in patients with antibody negative necrotizing myopathy?

This is a great question that speaks to the nuanced (and still-being-elucidated) association between malignancy and the increasingly better sub-divided different autoimmune myositis subtypes:

While anti-SRP and anti-HMGCR are the two myositis-specific antibodies (MSA) most closely associated with immune-mediated necrotizing myopathy (IMNM), this disease can also be seen in association with other MSA (and other antibodies).

As such, patients that have seronegative INMN may have false negative testing due to either the reliability of commercial testing/testing technique, prior treatment with B-cell depleting therapy, etc.

However, cohort studies have suggested there is a distinct subset of IMNM patients that are MSA seronegative, although it is ...