Severe Disabling Muscle Involvement as an Initial Presentation of Childhood Polyarteritis Nodosa - A Multi-Center Case Series
Bibliographic record
Abstract
Objectives Muscular polyarteritis nodosa (PAN), a disease that is predominantly confined to the skeletal muscle, has barely been described in adult literature and has been exceedingly rarely reported in children. The clinical presentation is non-specific, and the diagnosis is challenging and often delayed, requiring imaging evaluation and histopathological confirmation.[1] We aimed to describe the clinical presentation, complimentary workup, treatments given, and the outcome of this rare entity in a pediatric case series, underscoring the role of imaging evaluation in aiding the diagnosis. Methods A search of medical databases in 4 pediatric rheumatology referral centers identified 4 patients diagnosed with muscular PAN between 2015 and 2023. Clinical presentation and laboratory workup data, including genetics, imaging, histopathology, detailed follow-up, and treatment outcomes, were collected retrospectively and prospectively. Diagnosis required meeting the EULAR/PRINTO/PRES childhood-PAN criteria, with no findings suggesting major extra-muscular, visceral involvement. Results Four pediatric patients (2 Females and 2 Males), aged 8.5 to 15 years at presentation, were enrolled. All presented with severe disabling muscular pain, ill appearance, arthralgia, preserved muscle power, normal muscle enzymes, and elevated inflammatory markers. Three of them also had a fever when presented. MRI of the limbs revealed hyperintense signaling and edema of the affected muscles in cases 1,2,4, whereas PET-CT done in cases 1,2,3 showed increased uptake in the involved muscles, indicating myositis. Case 1,2,4 had skin and muscle biopsies with features compatible with PAN, while case 3 had PAN-supportive skin biopsy. All had initial proper responses to corticosteroids and immunosuppressants (Methotrexate or Azathioprine), but 3 of them experienced recurrent relapses necessitating prolonged therapy. None of the patients have developed visceral involvement or evolved to systemic PAN. Conclusion Pediatric practitioners should remain vigilant for the rare muscular-predominant PAN. Early recognition and diagnosis, aided by imaging tests such as MRI and occasionally PET-CT, along with histologic confirmation, are essential for prompt management and improved outcomes. [1.] Ganeshanandan LR. Semin Arthritis Rheum 2020;50(3):503-8.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".