Lung abscess differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Aditya Ganti M.B.B.S. [2]

Overview

Lung abscess must be differentiated from other lesions that present with similar symptoms such as cough, fever with chills and rigor and chest includes malignancy, pulmonary tuberculosis, Wegener's granulomatosis, rheumatoid nodules.

Differential

Disease	Clinical features Signs & symptoms									Radiological Findings	Characterstic feature
	Fever		Cough		Hemoptysis	Dyspnea	Chest pain	Weight loss	Night sweats
	High-grade	Low grade	Productive	Dry
Acute Lung abscess	+		+				+			Air fluid level	Foul smelling sputum H/o of prior infection or hospitalization Associated with risk factors like aspiration and alcoholism
Malignancy (primary lung cancer)		+		+	+			+	+	A coin-shaped lesion with thick wall(>15mm) is seen on chest x-ray with less ground glass opacities [2][3	Long H/o smoking Elderly male or female BAL positive for malignant cells CT guided biopsy is required for confirmation and differnatiation
Pulmonary Tuberculosis	+		+		+				+	Chest x-ray and CT demonstrates cavities in the upper lobe of the lung	People in endemic at high risk Cough >2 weeks with hemoptysis Acid fast stain positive for mycobacteria
Necrotizing Pneumonia	+		+		+		+			Multiple cavitary lesions	Acute life threatening condition Complication of pneumonia or lung abscess Multiple organisms responsible prompt treatment with antibiotics is required CBC positive for causative organism
empyema	+		+		+	+	+			Homogeneous consolidation involving one, or less commonly, multiple lobes	Blood culture positive for causative agent.
Bronchiectasis			+		+					Specific findings include linear lucencies tram tracking appearance, clustered cysts. Increased pulmonary markings, honeycombing, atelectasis and pleural changes.	High resolution CT helps in diagnosis .
Wegners granulomatosis			+		+	+				Pulmonary nodules with cavities and infiltrates	Seen mostly in female age group of 40-55 years Traid of Upper , lower respiratory tract and kidney disease Biopsy of involved organ confirms granulomas
Sarcoidosis	+		+		+			+	+	Bilateral adenopathy and coarse reticular opacities are seen on CXR	More common in African-american females Restrictive lung disease Biposy findings: epithelioid,granulomas, schaumann, asteroid bodies.
Rheumatoid nodule						+		+		Pulmonary nodules with cavitation are located in the upper lobe are seen on chest x-ray	Rheumatoid arthritis Positive for RF and ACP
Langerhans cell Histiocytosis						+	+	+		Thin-walled cystic cavities on chest x-ray	Exclusively afflicts smokers. Musculoskeletal and skin is involved Biopsy of the involved organ
Bronchiolitis obliterans			+		+	+	+			Common appearance on CT is patchy consolidation,often accompanied by ground-glass opacities and nodules.	Occupational exposure of industrial toxins Restrictive type of lung disease Biopsy often confirms the diagnosis

Causes of lung cavities	Differentiating Features	Differentiating lab findings	Diagnosis confirmation
Malignancy (Primary lung cancer)	Elderly male or female Chronic smokers Presents with a low-grade fever, absence of leukocytosis, systemic complaints weight loss, fatigue Absence of factors that predispose to gastric content aspiration, no response to antibiotics within 10 days Hemoptysis is commonly associated with bronchogenic carcinoma	A coin-shaped lesion with thick wall(>15mm) is seen on CXR with less ground glass opacities Bronchoalveolar lavage cytology shows malignant cells	Biopsy of lung
Pulmonary Tuberculosis	Mostly in endemic areas Symptoms include productive cough,night sweats, fever and weight loss	CXR and CT demonstrates cavities in the upper lobe of the lung	Sputum smear positive for acid-fast bacilli and nucleic acid amplification tests (NAAT) is used on sputum or any sterile fluid for rapid diagnosis and is positive for mycobacteria.
Necrotizing Pneumonia	Any age group Acute, fulminant life threating complication of prior infection >100.4F fever, with hemodynamic instability Worsening pneumonia-like symptoms	CXR demonstrates multiple cavitary lesions Pleural effusion and empyema are common findings	CBC is positive for causative organism
Loculated empyema	Children and elderly are at risk Pleuritic chest pain, dry cough, fever with chills Dullness to percussion decreased breath sounds, and reduced vocal resonance on examination	Empyema appears lenticular in shape and has a thin wall with smooth luminal margins	Thoracocentesis
Granulomatosis with polyangiitis (Wegener's)	Women are more commonly effected than man. Kidneys are also involved Upper respiratory tract symptoms , perforation of nasal septum, chronic sinusitis, otitis media, mastoiditis. Lower respiratory tract symptoms, hemoptysis, cough, dyspnea. Renal symptoms, hematuria, red cell casts	Pulmonary nodules with cavities and infiltrates are a frequent manifestation on CXR	Positive for P-ANCA Biopsy of the tissue involved shows necrotizing granulomas
Rheumatoid nodule	Elderly females of 40-50 age group Manifestation of rheumatoid arthritis Presents with other systemic symptoms including symmetric arthritis of the small joints of the hands and feet with morning stiffness are common manifestations.	Pulmonary nodules with cavitation are located in the upper lobe (Caplan syndrome) on Xray.	Positive for both rheumatoid factor and anticyclic citrullinated peptide antibody.
Sarcoidosis	More common in African-American females Often asymptomatic except for enlarged lymph nodes Associated with restrictive lung disease Erythema nodosum Lupus pernio (skin lesions on face resembling lupus) Bell palsy Epithelioid granulomas containing microscopic Schaumann and asteroid bodies	On CXR bilateral adenopathy and coarse reticular opacities are seen. CT of the chest demonstrates extensive hilar and mediastinal adenopathy Additional findings on CT include fibrosis (honeycomb, linear, or associated with bronchial distortion), pleural thickening, and ground-glass opacities.	Biopsy of lung shows non-caseating granuloma
Bronchiolitis obliterans (Cryptogenic organizing pneumonia)	Rare condition and mimics asthma, pneumonia and emphysema It is caused by drug or toxin exposure, autoimmune diseases, viral infections, or radiation injury People working in industries are at high risk Presents with fever, cough, wheezing and shortness of breath over weeks to months,	Common appearance on CT is patchy consolidation,often accompanied by ground-glass opacities and nodules.	Biopsy of the lung Pulmonary function tests demonstrate low fev1/fvc
Langerhans cell Histiocytosis	Exclusively afflicts smokers, with a peak age of onset of between 20 and 40 years. Clinical presentation varies, but symptoms generally include months of dry cough, fever, night sweats and weight loss. Skin is involved in 80% of the cases, scaly erythematous rash is typical.	Thin-walled cystic cavities are the usual radiographic manifestation, observed in over 50% of patients by either CXR or CT scans.	Biopsy of the lung