Quiz Answer April 2024

Radiological impression

• Cystic lesion in left upper lobe with surrounding consolidation and air-fluid level within
• Possibilities:
  • Duplication cyst
  • CPAM type 1

Post op HPE report

C/o left upper lobe lung cortical cyst with infected fluid

Gross:

Received flattened tissue piece measuring 1.5x 1x 0.4cm.

Micro:

Section examined from the cyst wall shows non-keratinizing stratified squamous lining epithelium with thick wall comprising of smooth muscle bundles.Occasional minor salivary glands with duct are noted. no infectious pathology or displasia or evidence of malignancy noted. Morphologically it appears to be esophageal duplication cyst.

Diagnosis:

Lung, left upper lobe of (cyst):- Suggestive of Cyst, duplication

Foregut duplication cysts

• Foregut duplication cysts are uncommon incidentally detected mediastinal masses on imaging.
• Duplication cysts usually share a common smooth muscle wall and blood supply.
• These are categorized into esophageal, bronchogenic, and neuroenteric cysts based on their embryological origin.
• Among these, enteric duplication cysts are the most common (50-70%) followed by bronchogenic cysts (7-15%).
• Bronchogenic cysts may be found either in the mediastinum (80-85%) or less frequently within the lung parenchyma (15-20%), in which case there is a predilection for the lower lobes.

Esophageal duplication cysts

• Most common fore gut duplication cysts and second most common location of gastrointestinal (GI) duplication cysts after the ileum.
• Prevalence: 0.1-0.2% in the general population.
• Embryology: they may result from a diverticulum of the dorsal bud of the primitive foregut or from aberrant recanalization of the gut.
• Location: These are found in the posterior mediastinum along the course of the esophagus, either completely separate from or in continuity with the esophagus. Majority are located along the distal esophagus (60%).
• Histopathology: these cysts are lined by squamous epithelium with gut signature layers.
• Clinical presentation: Usually asymptomatic, in large cysts, can develop symptoms secondary to mass effect on adjacent structures, including non-productive cough, stridor, chest pain, or dysphagia
• Complications: cardiac arrhythmia, retrosternal chest pain, cyst rupture, and secondary mediastinitis

Imaging findings

• X Ray: Esophageal duplication cyst may remain undetected on plain chest radiograph or seen as subtle posterior mediastinal mass due to displacement of stripes or planes.
• CT: Demonstrate relation of the duplication cyst with the esophagus and tracheobronchial tree.

Bronchogenic cysts

• Embryology: The cysts in a mediastinal location may develop as a result of abnormal budding, whereas the intrapulmonary cysts result from abnormal bronchial tree branching.
• Presentation: Most common with clinical symptoms being cough, fever, pain, and dyspnea.
• Complications: compression of adjacent structures, infection, or rupture into the pericardial or pleural cavities.
  The most common complication is compression of adjacent structures, in pediatric patients with tracheobronchial compression and resultant post-obstructive pulmonary infections

Imaging findings

• X ray:
  • The cysts appear as a soft-tissue density rounded structures, sometimes with compression of surrounding structures which can lead to air-trapping and a hyperlucent hemithorax.
  • The cysts can contain calcium oxalate, and dependent layering of calcific density material can be seen on some occasions.

• CT:
  • Bronchogenic cysts are seen as low attenuation, well-defined, homogenous, noncalcified, unilocular rounded, or spherical masses with smooth margins with CT attenuation values of 0-10 HU (fluid attenuation)
  • Attenuation values of greater than 20 HU could represent a complicated cystic component such as intracystic hemorrhage or proteinaceous material
  • In cases of superimposed infection, contrast enhancement of the walls or internal air-fluid levels may be seen (provided that the bronchogenic cyst is not communicating with tracheobronchial tree)