This file owns pediatric rheumatologic and MSK disease as a discrete clinical cluster matching the way Step 1 tests pediatric rheumatology — namely, JIA subtype reasoning, the limping child differential by age, pediatric skeletal dysplasias, and juvenile dermatomyositis.
Prerequisites
Approach to Inflammatory Arthritis & Rheumatoid Arthritis (the four-pillar inflammatory arthritis framework — joint pattern + autoantibody + extra-articular feature + acute-phase reactants — applied here to JIA subtypes with the pediatric modification that RF positivity is rare and uveitis is the canonical extra-articular feature)Systemic Lupus Erythematosus & Mixed Connective Tissue Disease (SLE recognition — pediatric SLE more often presents with renal and CNS involvement than adult SLE)Seronegative Spondyloarthropathies (HLA-B27 + enthesitis + axial-skeleton pattern in spondyloarthropathies — applied here to enthesitis-related JIA)Sjögren's Syndrome, Scleroderma & Inflammatory Myopathies (inflammatory myopathies — adult PM/DM/IBM owned there; juvenile dermatomyositis owned here as a pediatric-distinct entity with calcinosis cutis)Vasculitides & Systemic Granulomatous Disease (vasculitis vessel-size + ANCA framework — Kawasaki disease as medium-vessel vasculitis recognition + IVIG-within-10-days imperative owned there at the systemic-vasculitis level; HSP/IgA vasculitis tetrad owned there; this file owns the broader pediatric workup)Monoarthritis: Crystal Arthropathies, Septic Arthritis & Osteoarthritis (synovial fluid analysis framework — <2,000 WBC noninflammatory, 2,000–50,000 inflammatory, >50,000 septic — applied to pediatric septic arthritis)Metabolic Bone Disease (mineral homeostasis and skeletal mineralization — applied to rickets/osteomalacia owned there; pediatric metabolic bone disease beyond rickets)Muscle & Neuromuscular Disease (muscular dystrophies including DMD/Becker and congenital myopathies — recognized here as the floppy-infant and delayed-walking differential of pediatric weakness)Microbiology (organism biology — Kingella kingae as pediatric septic-arthritis pathogen <4 years; S. aureus and group B Streptococcus in neonates; Salmonella osteomyelitis in sickle cell disease)Basic embryology (limb bud formation, endochondral ossification of long bones, primary and secondary ossification centers, growth plate physis)Basic genetics (autosomal dominant FGFR3 in achondroplasia, autosomal dominant COL1A1/COL1A2 in osteogenesis imperfecta types I/IV, X-linked DMD in delayed-walking boys, GNAS post-zygotic mosaicism in McCune-Albright)