Spot Diagnosis

Cyst (cystic air space)

CT
A round, parenchymal space with a well-defined wall; usually air-containing when in the lung but without associated pulmonary emphysema; commonly used to describe enlarged air spaces in end-stage fibrosis of interstitial lung diseases and also in Langheran's cell histiocytosis and lymphangiomyomatosis

Fig. 1 shows cysts of honeycombing, whereas Fig. 2 shows cysts of histiocytosis X

Bronchiectasis

Pathology:
Irreversible dilatation of a bronchus or bronchi, often with thickening of the bronchial wall. Cylindric (tubular), saccular and cystic

Radiology:
Tubular or cystic, clustered spaces with or without air-fluid levels

Honeycombing

Pathology: A multitude of irregular cystic spaces in pulmonary tissue that are generally lined with bronchiolar epithelium and have markedly thickened walls comprised of dense fibrous tissue, with or without associated chronic inflammation

Plain Radiograph: A number of closely approximated ring shadows representing air spaces, 5-10mm in diameter with walls 2-3mm thick that resemble a true honeycomb: a finding whose occurrence implies "end-stage" lung. Often mistaken for bronchiectasis.

Bleb

Pathology:
A gas-containing space, within or contiguous to the visceral pleura of the lung

Radiology:
A local thin-walled lucency, contiguous with the pleura, usually at the lung apex - an inferred conclusion. Bulla or air cyst is preferred.

Pneumatocele

Radiology & Pathology
A thin-walled, gas-filled space within the lung, usually occuring in association with acute pneumonia (most commonly of staphyloccal etiology) and almost invariably transient. Fig. 2 shows an associated pneumothorax (arrowhead).

Bulla

Pathology: A sharply demarcated region of emphysema; a gas-containing space that may contain nothing but gas or may contain overdistended and ruptured alveolar septa and blood vessels

Plain Radiograph: A sharply demarcated area of avascularity within the lung, measuring 1.0cm or more in diameter and possessing a wall less than 1mm in thickness - this is the preferred term fo all thin-walled air-containing spaces in the lung with the exception of pneumatocele

On CT, a bulla is a round, focal air space, 1cm or more in diameter, demarcated by a thin wall; usually multiple or assocated with other signs of pulmonary emphysema

Mediastinal mass biopsy - transcostal approach

This is a 20-years old lady who presented with a mediastinal mass, predominantly in the aorto-pulmonary window. A CT-guided biopsy was suggested.

On the contrast-scan, it was possible to delineate the aorta and pulmonary arteries separate from the mass with a 1cm wide window between the two (Figs. 1, 2). Using a transcostal approach (Fig. 3), the cannula was slowly advanced (Fig. 4), until it lay within the centre of the mass, away from the vessels and bronchus. A biopsy was then performed (Fig. 5). This turned out to be lymphoma.

Air Crescent

"Air in a crescentic shape in a nodule or a mass, in which the air separates the outer wall of the lesion from an inner sequestrum, which most commonly is a fungal ball of Aspergillus species"

Lung abscess

Pathology:
An inflammatory mass, the central portion of which has undergone purulent liquefaction necrosis. It may communicate with the bronchial tree.

Plain Radiograph & CT:
A mass presumed to be caused by infection. The presence of gas within the mass with or without a fluid level, represents a cavity and implies communication with the bronchial tree. Otherwise a pulmonary mass can be considered to represent an abscess only be inference.

7mm solitary pulmonary (lung) nodule (SPN) biopsy

This 42 years old non-smoker had a small nodule on the chest radiograph. The CT showed a small 7mm nodule in the right apex, with a small central cavity. There was mild enhancement, which made the nodule indeterminate (Figs. 1, 2) and a CT-guided biopsy was offerred to the patient. The patient was extremely co-operative with his breath-holds, allowing accurate needle placement (Figs. 2, 3). Post-biopsy, there was mild peri-nodule hemorrhage (Fig. 4), with hemorrhage along the needle tract upto the pleura, which prevents the occurrence of a pneumothorax.

The report was of a necrotizing granuloma, most likely to be of tuberculous etiology, though acid-fast bacilli (AFB) were not found.