Round pneumonia

1. Cause and Etiology

Round pneumonia is primarily caused by bacterial infection, most commonly due to:

·         Streptococcus pneumoniae (most common)

·         Haemophilus influenzae

·         Mycoplasma pneumoniae (less commonly)

·         Staphylococcus aureus (rare, may cause cavitation)

Risk Factors

·         Age (typically <8 years)

·         Underdeveloped collateral ventilation

·         Immature alveolar interconnections

·         Poorly developed pores of Kohn and canals of Lambert

These anatomical and physiological factors in children prevent the usual spread of infection along alveolar paths, contributing to the round appearance.

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2. Pathophysiology

In young children, the underdeveloped interalveolar connections prevent widespread dissemination of infection across lung segments. As a result:

·         The infection remains localized in a small lung segment.

·         The confined infection develops into a spherical (round or oval) consolidation, instead of the typical lobar or segmental pattern.

·         The lesion may mimic a pulmonary mass radiographically.

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3. Epidemiology

·         Age: Most commonly seen in children under 8 years, particularly between 3–7 years of age.

·         Gender: No strong gender predilection.

·         Geographic distribution: Worldwide; more common during respiratory infection seasons (autumn and winter).

·         Represents up to 1% of all pneumonias in children.

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4. Clinical Presentation

Symptoms of round pneumonia are similar to typical pneumonia and include:

·         Fever

·         Cough

·         Tachypnea

·         Chest pain (may be pleuritic)

·         Malaise

·         Occasionally abdominal pain or vomiting (referred symptoms from lower lobe involvement)

On physical exam:

·         Decreased breath sounds

·         Crackles or rales

·         Dullness to percussion (less common)

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5. Imaging Features

Chest X-ray (Primary diagnostic tool):

·         Well-circumscribed round or oval opacity typically located in:

o    Posterior segments of the lower lobes (most common)

o    Less commonly in the upper lobes

·         Solitary lesion, typically 1–5 cm in diameter

·         Margins may be smooth or slightly lobulated

·         No cavitation or air bronchograms typically

CT Scan (Rarely needed):

·         Used when there is diagnostic uncertainty (e.g., distinguishing from a tumor or, abscess)

·         Shows a homogeneous soft-tissue attenuation mass

·         May reveal air bronchograms, helping differentiate from neoplasm

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6. Treatment

First-line treatment:

·         Empirical antibiotics, targeting S. pneumoniae:

o    Amoxicillin (oral or IV, depending on severity)

o    Alternatives: Cefuroxime, Ceftriaxone, or Azithromycin (if atypical pneumonia suspected)

·         Antipyretics for fever

·         Supportive care: hydration, rest

Duration:

·         Usually 7–10 days, with clinical improvement within 48–72 hours

Follow-up:

·         Repeat chest X-ray 4–6 weeks later to confirm resolution and exclude underlying pathology.

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7. Prognosis

·         Excellent prognosis with appropriate antibiotic treatment

·         Most lesions resolve completely without residual damage

·         Complications are rare, but may include:

o    Parapneumonic effusion

o    Lung abscess (rare)

o    Misdiagnosis as malignancy (leading to unnecessary workup)

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8. Differential Diagnosis

Because of its mass-like appearance, it’s important to distinguish round pneumonia from:

·         Pulmonary neoplasm (extremely rare in children)

·         Fungal infections (e.g., histoplasmosis)

·         Congenital pulmonary lesions (e.g., CPAM)

·         Lung abscess

·         Foreign body aspiration with post-obstructive pneumonia

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Summary Table

Feature	Round Pneumonia in Children
Cause	S. pneumoniae most common
Age group	<8 years (peak: 3–7 years)
Symptoms	Fever, cough, chest pain
X-ray findings	Solitary, round opacity (posterior lower lobes)
Treatment	Oral antibiotics (e.g., Amoxicillin)
Prognosis	Excellent; complete resolution in most cases
Key concern	Avoiding misdiagnosis as a tumor