Thick cavity in the lung is caused by all Except

A cavity is any gas-filled space in an area of consolidation, nodule or mass.Causes:Infective1. Staphylococcus aureus - thick-walled with a ragged inner lining. Usually multiple; no lobar predilection. Associated with effusion and empyema +- pyopneumothorax - almost invariable in children but less common in adults.2. Klebsiellapneumoniae - thick-walled with a ragged inner lining. More common in the upper lobes. Usually single but may be multilocular +- effusion. 3. Tuberculosis - thick-walled and smooth. Upper lobes and apical segment of lower lobes mainly. Usually surrounded by consolidation +- fibrosis.4. Aspiration - look for foreign body, e.g. tooth. 5. Others - Gram-negative organisms, actinomycosis, nocardiosis, histoplasmosis, coccidioidomycosis, aspergillosis, hydatid and amoebiasis.Neoplastic 1. Lung cancer - thick-walled with an eccentric cavity. Predilection for the upper lobes. Found in 2-10% of carcinomas and especially if peripheral. More common in squamous cell carcinomas and may then be thin-walled 2. Metastases - thin- or thick-walled. May involve only a few of the nodules. Seen especially in the squamous cell, colon and sarcoma metastases.3. Lymphoma (Hodgkin's disease) - thin- or thick-walled and typically in an area of infiltration. With hilar/mediastinal lymph node enlargement.Vascular Infarction - primary infection due to a septic embolus commonly results in cavitation. There may be the secondary infection of an initially sterile infarct. An aseptic cavitating infarct may subsequently become infected: teiary infection. Aseptic cavitation is usually solitary and arises in a large area of consolidation after about 2 weeks. If localized to a segment, the commonest sites are apical or the posterior segment of an upper lobe or apical segment of lower lobe (cf. lower lobe predominance with non-cavitating infarction). Majority have scalloped inner margins and cross-cavity band shadows +- effusion.In abnormally modeled/destroyed lung or congenital1. Infected emphysematous bulla - thin-walled. +- Air-fluid level.2. Sequestrated segment - thick- or thin-walled. 66% in the left lower lobe, 33% in the right lower lobe. +- Air-fluid level.+- Surrounding pneumonia.3. Bronchogenic cyst - in medial third of lower lobes. Thin-walled.+- Air-fluid level.+- Surrounding pneumonia.Inflammatory1. Wegener's granulomatosis - cavitation in some of the nodules. Thick-walled, becoming thinner with time.Can be transient.2. Rheumatoid nodules - thick-walled with a smooth inner lining. Especially in the lower lobes and peripherally.Well-defined. Become thin-walled with time. 3. Progressive massive fibrosis - predominantly in the mid and upper zones. Thick-walled and irregular.Background nodularity.4. Sarcoidosis - thin-walled. In early disease due to a combination of central necrosis of areas of coalescent granulomas and a check-valve mechanism beyond paial obstruction of airways by endobronchialsarcoidosis.Traumatic1. Haematoma - peripheral. Air-fluid level if it communicates with a bronchus. 2. Traumatic lung cyst - thin-walled and peripheral. Single or multiple.Unilocular or multilocular. Distinguished from cavitating hematomas as they present early, within hours of the injury.(Ref: Chapman and Nakielny's Aids to Radiological Differential Diagnosis 6thEtd, page no.85)