Полезные материалы за все 6 курсов / Учебники, методички, pdf / Kaplan Pediatrics USMLE 2CK 2021

Note

X-rays for patients with osteomyelitis are initially normal. Changes are not seen until 10−14 days.

DISORDERS OF THE UPPER LIMB

Nursemaid Elbow

•When longitudinal traction causes radial head subluxation

•History of sudden traction or pulling on arm

•Physical exam reveals a child who refuses to bend the arm at the elbow and holds the arm with adduction, internal rotation, and pronation

•Treatment—rotate hand and forearm to the supinated position with pressure of the radial head → reduction

OSTEOMYELITIS AND SEPTIC ARTHRITIS

•Etiology

−Osteomyelitis:

°S. aureus most common overall, in all

°Pseudomonas—puncture wound

°Salmonella common in sickle anemia; S. aureus still most common

−Septic arthritis:

°Almost all S. aureus

°Most in young children; hematogenous; LE > UE and other parts of body

•Presentation

−Pain with movement in infants

−Older—fever, pain, edema, erythema, warmth, limp, or refusal to walk (acute, toxic, high fever)

•Diagnosis

−Blood culture, CBC, ESR

−Radiographic studies:

°Initial plain film if diagnosis not obvious to exclude other causes—trauma, foreign body, tumor; trabecular long bones do not show changes for 7−14 days (septic arthritis shows widening of joint capsule and soft-tissue edema)

°Ultrasound for septic arthritis—joint effusion, guide localization of drainage

°Best test is MRI for osteo; very sensitive and specific

°Bone scan—can be valuable to augment MRI, especially if multiple foci are suspected or vertebrate

−Definitive—aspirate for culture and sensitivity

°Osteomyelitis → bone biopsy for culture and sensitivity

°Septic arthritis → ultrasound guided arthrocentesis for culture and sensitivity

•Treatment

−Intravenous antibiotics—always cover for Staphylococcus initially (treatment for osteo much longer)

Learning Objective

Diagnose and describe management of juvenile idiopathic arthritis, systemic lupus erythematosus, Kawasaki disease, and Henoch-Schonlein purpura

JUVENILE IDIOPATHIC ARTHRITIS (JIA)

A 7-year-old girl complains of pain and swelling of the left wrist and right knee off and on for the past 3 months. She has been previously healthy. The pain is worse in the morning and improves throughout the day. Physical examination is remarkable for swelling and effusion of the right knee, with decreased range of motion.

•Definition—idiopathic synovitis of peripheral joints associated with soft-tissue swelling and joint effusion

•Pathophysiology

−Vascular endothelial hyperplasia and progressive erosion of articular cartilage and contiguous bone

−Immunogenetic susceptibility and an external trigger

−DR8 and DR5

•Clinical presentation

−Morning stiffness; easy fatigability

−Joint pain later in the day, joint swelling, joints warm with decreased motion, and pain on motion, but no redness

•Criteria for diagnosis: the diagnosis of JIA is a clinical one, and one of exclusion. There are many diseases that mimic it and there are no pathognomonic diagnostic labs. The clinical exclusion of other diseases is essential, as lab studies may be normal.

−Age of onset: <16 years

−Arthritis in 1 or more joints

−Duration: ≥6 weeks

−Onset type by disease presentation in first 6 months

−Exclusion of other forms of arthritis, other connective tissue diseases and vasculitides, Lyme disease, psoriatic arthritis, inflammatory bowel disease, lymphoproliferative disease

Note

A positive rheumatoid factor in JIA is indicative

of a poor prognostic outcome.

Note

A pregnant woman with SLE will transfer IgG autoantibodies (usually anti-Ro) across the placenta at 12 to 16 weeks. This can cause a variety of manifestations, the most important being congenital heart block. All are temporary, except for the heart block, which may require permanent pacing.

SYSTEMIC LUPUS ERYTHEMATOSUS (SLE)

A 10-year-old girl presents with fever, fatigue, and joint pains. Physical examination is remarkable for a rash on the cheeks, swelling of the right knee, and pericardial friction rub. Initial laboratory tests reveal anemia and an elevated blood urea nitrogen and creatinine.

•Etiology

–Autoantibodies, especially against nucleic acids including DNA and other nuclear antigens and ribosomes; blood cells and many tissue-specific antigens; immune complex deposition

°Immune complex deposition in the dermal/epidermal junction is specific for SLE (called the lupus band test)

°Diffuse proliferative glomerulonephritis significantly increases risk for severe renal morbidity (pathology varies from minimal mesangial changes to advanced sclerosing nephritis)

•Epidemiology

–90% female

–Compared with adults, children have more severe disease and more widespread organ involvement

–Highest rate among African-Americans, Hispanics, Asians, Native-Americans and Pacific Islanders

–Rare age <5 years and only up to 20% present age <16 years, so usual presentation is mid-to-late adolescence

•Clinical presentation

–Most common is a female with fever, fatigue, rash, hematological abnormalities (anemia of chronic disease or hemolytic; thrombocytopenia, leukopenia) and arthralgia/arthritis

–Renal disease is often asymptomatic, so needs careful monitoring of UA and BP; presents as either flares with quiescent periods or a more smoldering disease (hypertension, glomerulonephritis, nephrosis, acute renal failure)

–Neuropsychiatric complications can occur with or without active disease

–Less common: lymphadenopathy, HSM/hepatitis, abdominal pain, diarrhea, melena

•Lab studies

–Nonspecific: elevated ESR, CRP, platelets, anemia, elevated WBC or leukopenia/

lymphopenia; decreased CH50, C3, C4 (typically decreased in active disease and increases with treatment)

–+ANA: present in 95–99% of SLE patients but has poor specificity; does not reflect disease activity; first screening test

–+anti-dsDNA: more specific (but not 100%) and correlates with disease activity, especially nephritis

–+anti-Smith antibody (anti-Sm): 100% specific but no disease activity correlation

–Antiribonucleoprotein antibodies: increased with Raynaud phenomenon (blanching of fingers) and pulmonary hypertension; high titer may be diagnostic of mixed CT disorder; antiribosomal-P-antibody is a marker for lupus cerebritis

–Anti-Ro antibody (anti-SSA): IgG maternal antibodies crossing the placenta and produce transient neonatal lupus; may suggest Sjögren syndrome

–Anti-La (anti-SSB): also increased risk of neonatal lupus; may be associated with cutaneous and pulmonary manifestations of SLE or isolated discoid lupus; also seen in Sjögren syndrome

–Antiphospholipid antibodies (APL; including anticardiolipin): when a clotting event occurs in the presence of APL antibodies, the antiphospholipid syndrome is suspected:

°Increased risk of arterial and venous thrombosis

°Livedo reticularis

°Raynaud phenomenon produces cyanosis and then erythema; caused by cold stress or emotional stress; initial arterial vasoconstriction creates hypoperfusion then venous stasis, followed by reflex vasodilation

°Positive lupus anticoagulant: may give a false-positive serological test for syphilis; also seen in patients with neurological complications

°Recurrent fetal loss

–Coombs positive: hemolytic anemia

–Antiplatelet antibodies: thrombocytopenia

–Antithyroid antibodies: autoimmune thyroiditis

–Antihistone antibodies: may be found with drug-induced lupus; may act as a trigger in those prone to lupus or cause a reversible syndrome hepatitis is common (otherwise rare in children with lupus); more common drugs: minocycline, tetracycline, sulfasalazine, penicillin, nitrofurantoin, IH, many antihypertensives, anticonvulsants, procainamide, lithium, glyburide, statins, PTU, penicillamine, chlorpromazine, some biologicals

Note

Diagnosis of SLE— “MD Soap ’n Hair”

•Malar rash

•Discoid rash

•Serositis

•Oral ulcers

•ANA-positive

•Photosensitivity

•Neurologic disorders

•Hematologic disorders

•Arthritis

•Immune disorders (LE [lupus erythematosus] prep test, anti-DNA, Smith)

•Renal disorders

Note

The most serious sequelae of Kawasaki disease are cardiac-related.

192

•General principles of treatment

–Sunscreen and direct sun avoidance

–Hydroxychloroquine for all, if tolerated

–NSAIDs for joints

–Corticosteroids for more severe disease, especially renal

–Steroid-sparing immunosuppressives for severe disease (proliferative GN, continued vasculitis, pulmonary hemorrhage, severe persistent CNS disease)

–LMW heparin is drug of choice for thrombosis, APL, lupus anticoagulant

Clinical Recall

When considering a diagnosis of systemic lupus erythematosus (SLE), which antibody test would provide both high specificity and correlate with disease activity?

A.ANA

B.Anti-RNP

C.Anti-dsDNA

D.Anti-Smith

E.Antihistone

Answer: C

NEONATAL LUPUS

•Passive transfer of IgG across placenta; most is maternal anti-Ro and anti-La

•Mostly presents at age 6 weeks with annular or macular rash affecting the face, especially periorbital area, trunk and scalp after exposure to any UV light; generally lasts 3–4 months

•At risk for future pregnancies; baby is at some risk for future autoantibody disease

•May manifest with any SLE finding, but all resolve unless there is congenital heart block (can be detected in utero at 16 weeks); is permanent; if it is third degree, pacing is usually required.

KAWASAKI DISEASE

An 18-month-old has had fever for 10 days. He now has conjunctival injection, a very red tongue and cracked lips, edema of the hands, and a truncal rash.

•Etiology

–Many factors point to an infective cause but no specific organism has been found

–Genetic susceptibility: highest in Asians irrespective of location and in children and sibs of those with KD

–KD-associated antigen in cytoplasmic inclusion bodies of ciliated bronchial epithelial cells, consistent with viral protein aggregates; suggests respiratory portal of entry

–Seems to require an environmental trigger

•Epidemiology

–Asians and Pacific Islanders at highest risk

–80% present at age <5 years (median is 2.5 years) but may occur in adolescence

–Poor outcome predictors with respect to coronary artery disease: very young age, male, neutrophilia, decreased platelets, increased liver enzymes, decreased albumin, hyponatremia, increased CRP, prolonged fever

•Pathology

–Medium size vasculitis, especially coronary arteries

–Loss of structural integrity weakens the vessel wall and results in ectasia or saccular or fusiform aneurysms; thrombi may decrease flow with time and can become progressively fibrotic, leading to stenosis

•Diagnosis

Absolute requirement: fever ≥5 days (≥38.3 C [≥101 F]), unremitting and unresponsive;­ would last 1−2 weeks without treatment plus any 4 of the following:

–Eyes: bilateral bulbar conjunctivitis, non-exudative

–Oral: diffuse oral and pharyngeal erythema, strawberry tongue, cracked lips

–Extremities: edema and erythema of palms and soles, hands and feet acutely; subacute (may have periungual desquamation of fingers and toes and may progress to entire hand)

–Rash: polymorphic exanthema (maculopapular, erythema multiforme or scarlatiniform with accentuation in the groin); perineal desquamation common in acute phase

–Cervical lymphadenopathy: usually unilateral and >1.5 cm, nonsuppurative

Associated symptoms: GI (vomiting, diarrhea, pain); respiratory (interstitial infiltrates, effusions); significant irritability (likely secondary to aseptic meningitis); liver (mild hepatitis, hydrops of gallbladder); GU (sterile pyuria, urethritis, meatitis); joints (arthralgias/arthritis— small or large joints and may persist for several weeks)

•Cardiac findings

–Coronary aneurysms: up to 25% without treatment in week 2–3; approximately 2−4% with early diagnosis and treatment; giant aneurysms (>8 mm) pose greatest threat for rupture, thrombosis, stenosis and MI; best detected by 2D echocardiogram

–Myocarditis: in most in the acute phase; tachycardia out of proportion to the fever and decreased LV systolic function; occasional cardiogenic shock; pericarditis with small effusions. About 25% with mitral regurgitation, mild and improves over time; best detected by 2D echocardiogram plus EKG

–Other arteries may have aneurysms (local pulsating mass)

Note

Any child suspected of having Kawasaki disease should have an echocardiogram.

Note

Kawasaki disease is one of the few instances in pediatrics for which you would use aspirin.

(It is usually avoided because of the risk of developing Reye syndrome.)