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appropriate cultures from identified sources of infection (e.g., skin abscess, cellulitis) Examine cerebrospinal fluid when CNS infection is suspected Appropriate antibiotics should be promptly administered to all febrile neutropenic patients while awaiting culture results Clinical Recognition There are a wide range of causes of neutropenia in children Etiologies of neutropenia can be divided into congenital or acquired Congenital forms of neutropenia such as severe congenital neutropenia and cyclic neutropenia arise from specific genetic mutations Several syndromes including myelokathexis/WHIM syndrome, Shwachman– Diamond syndrome, and Chédiak–Higashi syndrome are also associated with neutropenia Acquired forms arise from infections, drugs, or autoimmunity ( Table 93.7 ) and are especially common in patients undergoing chemotherapy for oncologic processes Immune-mediated conditions are caused by neutrophil-specific antibodies These include neonatal alloimmune neutropenia, a severe but self-limited neutropenia secondary to transplacental maternal antibodies, and primary autoimmune neutropenia Idiopathic neutropenia occurs without evidence of congenital, immune, or cyclic neutropenia Triage The most important triage consideration is to identify febrile neutropenic patients, and among those to recognize ill-appearing children who require aggressive management Early administration of broad-spectrum IV antibiotics should be a primary focus TABLE 93.7 CAUSES OF NEUTROPENIA AND DISORDERS OF NEUTROPHIL FUNCTION IN CHILDREN Inherited neutropenia Severe congenital neutropenia—includes autosomal dominant (neutrophil elastase mutation), autosomal recessive Kostmann disease Cyclic neutropenia Dyskeratosis congenita Shwachman–Diamond syndrome Congenital neutropenia associated with pigmentation and or immune disorders— Chédiak–Higashi syndrome, Griscelli syndrome, Hermansky–Pudlak syndrome Reticular dysgenesis, myelokathexis/WHIM syndrome Other neutropenias—metaphyseal chondrodysplasia or cartilage–hair hypoplasia, Barth syndrome, glycogen storage type 1b, Gaucher disease, Niemann–Pick disease Acquired neutropenias Drugs and chemical toxins Anticonvulsant: carbamazepine, valproate Antimicrobial: sulfonamides, penicillins, trimethoprim/sulfamethoxazole, quinine Antipsychotic: clozapine, olanzapine, phenothiazines Antirheumatic: gold, levamisole, penicillamine Antithyroid: methimazole, propylthiouracil Other: aminopyrine, deferiprone, rituximab, levamisole-adulterated cocaine, phenothiazines, thiouracil Dose-dependent myeloid suppression, cytotoxic drugs, antimetabolites Iatrogenic causes (radiotherapy, radioactive treatments) Infection (bacterial, viral, rickettsial, protozoal)—usually transient Bacterial: Brucella , paratyphoid, tuberculosis, tularemia, typhoid Viral: CMV, EBV, HIV, influenza, parvovirus B19, hepatitides A, B; RSV, rubella, measles, varicella Rickettsial: Anaplasma phagocytophilum, other rickettsia Protozoan: Plasmodium vivax, Plasmodium falciparum Bone marrow infiltration or failure (leukemia, aplastic anemia, hypogammaglobulinemia, hemophagocytic lymphohistiocytosis) Nutritional deficiencies (starvation; anorexia nervosa; vitamin B12 , folate, zinc, and copper deficiencies) Immune neutropenias (collagen vascular diseases, Felty syndrome, neonatal isoimmune neutropenia, autoimmune neutropenia including chronic benign neutropenia of childhood) Disorders of neutrophil function Abnormal adhesion (leukocyte adhesion deficiency) Abnormal chemotaxis (hyperimmunoglobulin E syndrome) Abnormal opsonization and ingestion (complement deficiency, leukocyte adhesion deficiency) Abnormal degranulation (Chédiak–Higashi syndrome) Abnormal oxidative metabolism (chronic granulomatous disease, myeloperoxidase deficiency) Acquired disorders of phagocytic dysfunction (malnutrition, malignancies, severe burns) Initial Assessment/H&P Attention to frequency, site, and severity of prior infections is critical Ascertain the height of fever, other constitutional symptoms, the presence of oral inflammation, and history of other infections Family history may help diagnose cyclic neutropenia Detailing exposure to medications and toxins including herbal or “natural” remedies may reveal a cause of acquired disease Congenital neutropenia usually presents in infancy with severe or recurrent bacterial or fungal infections typically of the skin, mucosa, or lungs Explore the family history for recurrent infections or deaths in early childhood that might suggest a congenital neutropenia On physical examination, evidence of mouth ulcers as well as gingival, periodontal, or dental issues may indicate neutropenia Acute abdominal pain and fever should raise concerns about neutropenic colitis (also known as typhlitis) and sepsis Examine the perirectal and anal areas for cellulitis In the absence of neutrophils, the degree of induration may lead clinicians to underestimate the severity of infection Management/Diagnostic Testing Management of neutropenic patients depends on the degree and etiology of the neutropenia (see Table 93.7 ) Neutropenic oncology patients are a special category (see Chapter 98 Oncologic Emergencies ) Febrile neutropenic patients require CBC and blood cultures For ill-appearing febrile patients and febrile neutropenic patients with poor marrow function (congenital neutropenias and bone marrow failure syndromes), treat with broad-spectrum IV antibiotic therapy that includes antibiotics effective against skin and gastrointestinal flora, and anaerobic coverage if abdominal pain is present An example initial regimen may include ceftriaxone, vancomycin, and metronidazole For persistent fever (>4 days), empiric antifungal coverage should be considered Febrile neutropenic patients with normal marrow function (autoimmune-mediated neutropenias) who are well appearing with reassuring vital signs and no history of severe infection are often managed as outpatients following a dose of ceftriaxone; fluoroquinolones are the most common alternative in allergic patients Neutropenia is occasionally discovered during an evaluation for fever In most of these instances, both the fever and neutropenia result from a viral illness Serious secondary bacterial infections are unlikely with mild to moderate neutropenia; however, because the neutropenia usually cannot be attributed with certainty to a viral illness,