• Inflammation/infection of the skin/subcutaneous tissues
• Often classified by body area involved
  • Periorbital
  • Orbital
  • Buccal
  • Peritonsillar
  • Extremity
  • Breast

• Staphylococcus aureus
• Streptococcal (group A b-hemolytic and S. pneumoniae)
• Haemophilus influenzae type b (rare since advent of childhood immunization)
• Pseudomonas aeruginosa, other gram-negative bacilli, anaerobic bacteria (immunocompromised children)

• Most commonly secondary to local trauma
  • Abrasions
  • Lacerations
  • Bites
  • Excoriated dermatitis
  • Other breach in the integument
• May develop secondary to local invasion or infection (e.g., sinusitis leading to orbital cellulitis)
• Hematogenous dissemination (classically H. influenzae type b)

• Cellulitis secondary to local trauma of the integument is by far the most common cause of cellulitis in children.
• Incidence of hematogenous disease is dramatically declining as H. influenzae type b disease disappears.

• Periorbital
  • Usually secondary to local trauma
    • Impetigo
    • Varicella
    • Eczema
  • Much less common, hematogenous
  • Rarely associated with infectious conjunctivitis
• Orbital
  • Most commonly associated with severe sinusitis
  • Less common, dental abscess
• Buccal
  • Same pathophysiology and epidemiology as periorbital cellulitis (not including conjunctivitis)
• Peritonsillar
  • Commonly secondary to severe group A b-hemolytic streptococcal pharyngitis
  • Often progresses or associated with a peritonsillar abscess
• Extremity
  • Almost always secondary to local trauma
• Breast
  • Usually with mastitis

• Local as well as distant spread of infection is possible.
• Suppuration and abscess formation may occur (e.g., peritonsillar abscess).
• Extremity cellulitis may extend into the deep tissues to produce an arthritis or osteomyelitis, or it may extend proximally as a lymphangitis.
• Orbital cellulitis may be complicated by visual loss and/or cavernous sinus thrombosis.
• Prior to widespread immunization against Haemophilus influezae type b, the bacteremia associated with facial cellulitis was not uncommonly associated with pneumonia, meningitis, pericarditis, epiglottitis, as well as arthritis and osteomyelitis.

• Allergic angioedema is the most common entity; it can usually be excluded by its lack of tenderness and the absence of fever.
• Contact dermatitis, similarly, is distinguished by its painlessness, pruritus, and the Koebner phenomenon (appearance of isomorphic lesions in the lines of scratching).
• A traumatic contusion may be mistaken for cellulitis, but the history should be confirmatory.
• Severe conjunctivitis may mimic periorbital cellulitis; conjunctival injection, chemosis, and discharge usually implicate a conjunctivitis.
• “Popsicle panniculitis,” a cold-induced fat injury to the cheeks of infants, may be almost indistinguishable from buccal cellulitis; a history of cold weather exposure, or ice or popsicle sucking should be sought.
• A primary eye malignancy (retinoblastoma), locally invasive tumor (rhabdomyosarcoma), or metastatic disease (neuroblastoma, leukemia, lymphoma), may simulate periorbital or orbital cellulitis.

Question: An expanding, red, painful area of swelling, with or without fever
Significance: The common presentation

Question: Mild constitutional symptoms
Significance: May occur with local disease; serious systemic symptoms, with bacteremic disease.

Question: History of local trauma to the integument
Significance: This is the clue to the portal of bacterial entry

Finding: Erythema, edema, tenderness, and warmth
Significance: Usual presentations

Finding: A red, lymphangitic streak
Significance: May extend proximally from the extremity

Finding: Regional adenopathy
Significance: Is not uncommon

Test: CBC
Significance: May be normal or show leukocytosis in more severe cases.

Test: Blood cultures
Significance: Though the incidence of invasive H. influenzae type b disease is rapidly declining, blood cultures still should be obtained in facial and other serious cases of cellulitis; in children with H. influenzae type b cellulitis, 80% to 90% of blood cultures are positive.

Test: Needle aspiration and culture
Significance: “Leading edge” cultures, etc., are generally not indicated.

Test: Lumbar puncture
Significance: Indicated only in ill-appearing children and young infants (rule out sepsis)

Test: X-ray studies
Significance: Sometimes helpful to rule out complications such as arthritis or osteomyelitis

Test: Head CT scan
Significance: Important in orbital cellulitis to delineate extent of disease, and also in some cases when distinction from periorbital cellulitis is clinically difficult

Test: Bone marrow aspirate and biopsy (as well as CT scan)
Significance: To rule out malignancies

• Most cases of uncomplicated cellulitis can be treated with oral antibiotics active against Staphylococcus and Streptococcus (e.g., amoxicillin-clavulanate, cephalexin, erythromycin).
• Ill-appearing children or extensive cellulitic lesions require intravenous antibiotics.
• Initial intravenous therapy should be directed against S. aureus and Streptococcus (e.g., oxacillin, nafcillin, or cefazolin).
• When hematogenous dissemination is a strong possibility, an agent active against H. influenzae type b also should be added (e.g., ceftriaxone, cefotaxime, cefuroxime, or chloramphenicol).
• Neonates (<7 weeks of age) should have gram-positive and gram-negative coverage (e.g., oxacillin or nafcillin and gentamicin or oxacillin or nafcillin and cefotaxime) to cover the enterics as well.
• The duration of antibiotics (intravenous and oral) should generally be 7 to 10 days.
• Abscesses should be surgically drained.

• Rapid, steady improvement should be expected.
• If daily improvement is not noted, inappropriate antimicrobial therapy, a deeper infection or abscess, or some other complication should be suspected.

• Avoid trying to make distinction between staphylococcal and streptococcal by clinical presentation—it is always safest to cover cellulitis patients with an agent active against both (i.e., penicillin and amoxicillin are not good empiric choices).
• The “violaceous hue” touted as an indicator of H. influenzae type b cellulitis is neither sensitive nor specific.

Q: Is ophthalmology consultation necessary in all cases of periorbital cellulitis?
A: Ophthalmology consultation is not necessary in simple, uncomplicated cases of periorbital cellulitis that clearly have no associated proptosis, limitation in extraocular eye movement, or visual impairment that would suggest a more serious orbital cellulitis; if, however, the diagnosis is in question, consultation is indicated.

Q: Is cefuroxime adequate coverage in cases of facial cellulitis?
A: If meningitis is suspected, cefuroxime should not be used, as its CSF penetration is suboptimal.