A New Lesion on the Sacroiliac Joint Changes What “Escalation” Even Means
The bisphosphonate-versus-biologic argument assumed this was still bone-only disease. A new lesion in a different kind of location means that assumption needs checking before either drug gets chosen.
Deep, aching pain over the left clavicle that worsened at night and did not improve with rest first brought Ruby N., a 13-year-old competitive swimmer, to her pediatrician's attention eight months ago — a pattern that led to imaging rather than an assumption of soft-tissue strain from training. MRI showed multifocal marrow edema and osteitis involving the clavicle and, on a full-body sequence obtained to look for additional silent lesions, the distal right tibia as well. A bone biopsy of the clavicular lesion was culture-negative and showed sterile inflammatory changes without malignant cells, ruling out both infection and the bone tumor her family had feared most — the two diagnoses any painful, imaging-abnormal bone lesion in a child this age has to exclude before CRMO can be accepted as the answer. She has no psoriasis, no palmoplantar pustulosis, and no acne, findings that would point toward the broader SAPHO spectrum rather than isolated CRMO, and her HLA-B27 has come back negative.
Naproxen at an appropriately dosed, weight-based regimen has been her only treatment for the past four months, with real but partial benefit — her pain scores have dropped from a daily 7 out of 10 to an intermittent 4, and she has returned to swim practice, though not yet at full training volume. A repeat whole-body MRI obtained this week, done specifically to assess treatment response, showed the original two lesions essentially unchanged in extent, plus a new area of marrow edema involving the left sacroiliac joint that was not present eight months ago — a genuinely new finding, not merely persistence of what was already known, and one that sits in a different anatomic category than her prior clavicular and tibial lesions.
That single new lesion is the fact reshaping the whole conversation: a third CRMO-typical long-bone focus would have simply confirmed ongoing NSAID-refractory disease. A sacroiliac lesion, before its own specific imaging pattern is read carefully, could mean either that, or something the team has not yet been treating for at all.
What the sacroiliac joint is actually showing
Four months of NSAID therapy with only partial relief and a new lesion on repeat imaging is a real escalation trigger by any reasonable threshold. Miettunen and colleagues' case series showed genuine pain and radiographic improvement with pamidronate in NSAID-refractory CRMO, and I'd rather step to that targeted option before moving to broader systemic immunosuppression.
I'd push back on 'targeted' as the right word here. A new sacroiliac lesion suggests this disease may be broader than the two long-bone foci we started with, and a bisphosphonate addresses bone turnover — it doesn't necessarily touch the underlying inflammatory drive the way anti-TNF therapy would, which also has its own case-series support, in Eleftheriou and colleagues' anti-TNF series, in bisphosphonate-refractory CRMO.
If we think a biologic is where this is ultimately headed once the disease looks this multifocal, adding pamidronate first just delays that, with its own real infusion burden — acute-phase reaction, a multi-day admission, hypocalcemia monitoring — for a step we may not actually need.
I think you're both reasoning from an assumption about what that new lesion actually is, and I'd rather confirm it before either plan moves forward. A sacroiliac lesion in CRMO and one consistent with juvenile spondyloarthritis can look genuinely different — bilaterality, the specific erosion and marrow edema pattern — and that distinction isn't cosmetic, it changes whether anti-TNF is an escalation choice within CRMO or the established, better-evidenced treatment of a different, overlapping diagnosis.
I'd want to formally re-read this MRI with that specific question before either of you commits to a next drug — the imaging she already has can very likely answer it without needing to wait for anything new.
Naproxen was continued unchanged and a formal radiology re-read of the sacroiliac finding was scheduled before either escalation drug was started — the team's explicit agreement that the imaging question, not either treatment argument, needed to be resolved first.
Not agreed, and stated as genuinely open rather than resolved by the imaging plan alone: even once the sacroiliac lesion is characterized, the Pediatric Rheumatologist and Clinical Pharmacologist have not settled whether a CRMO-typical read would still favor trying pamidronate first, or whether the disease's now-broader distribution argues for going straight to a biologic regardless of that specific pattern. Both agreed only that the imaging result should inform that conversation directly rather than be treated as a side issue to it.