Complicated Cases Discussed in Pediatric Thieves Market

CHICAGO—A slate of pediatric rheumatologists recounted a series of interesting cases, ranging from a teenage track athlete with mysterious fatigue to a young adult with worsening headache, memory changes and a complex medical history, in ACR Convergence 2025’s Pediatric Thieves Market, in which the audience decided which case was most compelling.

All of the cases involved a winding road to diagnosis and left clinicians with important lessons to share in their presentations.

15-Year-Old Track Star

Drayton Harvey, PhD, a fourth-year medical student in the MD-PhD program at the University of Southern California, Los Angeles, and the California Institute of Technology, Pasadena, discussed the case of a 15-year-old track star who could run a 5.5-minute mile in the 1600-meter race. At a track meet, he’d only been able to jog and had been exhausted by the end. It was later learned he’d been having trouble keeping up with his family on a ski trip a few months earlier.

He was found to have a creatine kinase of 30,000 u/L (reference range: 10–205 u/L) and was hospitalized, then discharged after a week with a rhabdomyolysis diagnosis. But he was soon hospitalized again with worsening weakness. On a neuromuscular test, he was found to have mostly normal strength but was hyperreflexic. He had a positive Gower sign, a sign of weakness in the hips and thighs. A genetic panel was unremarkable, and he was sent home to rest and get additional work up as an outpatient.

After being unable to tie his shoes or get through a half day of school, he was hospitalized again. An expanded myositis panel was sent out, he was found to have oropharyngeal dysphagia that he was able to clear with throat clearing.

After a five-day steroid pulse, he regained strength and consistently met his occupational and physical therapy goals.

The results of the muscle biopsy showed scattered degenerating and regenerating fibers and few lymphocytes or spare macrophages on hematoxylin and eosin (H&E) staining; MHC-1 staining showed patchy sarcolemmal positivity; and he had positive LC3 staining.

The diagnosis was a rare case of immune-mediated necrotizing myositis (IMNM). Dr. Harvey said part of what made the case vexing was the lack of cutaneous abnormalities, which are often seen in IMNM. He said IMNM can get confused with limb girdle muscular dystrophy (MD) because MD can present in such a heterogeneous way.

“Most importantly,” Dr. Harvey said, “we sent an expanded myositis panel and that is about the only way for us to get antibody positivity in these cases. It’s not on your traditional, more narrow myositis panel.”