History 67-year-old man with 3 days of fever, productive cough and pleuritic chest pain. T 38.9 °C, RR 24, SpO₂ 93% on room air.
Frontal chest radiograph · Click an image to enlarge.
Answer each question aloud before you reveal it. Marks and domains appear only in the revealed answers, as in the exam.
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Q1 What is the pertinent finding, and where is it?
Reveal answer
A Annotated 3 marks Observation
- Airspace opacity in the right mid to lower zone, peripherally (1)
- Sharp upper margin along the horizontal fissure (1)
- Right hemidiaphragm preserved; right heart border largely preserved (0.5)
- No visible effusion, cavitation or volume loss (0.5)
Examiner note The right heart border is not clearly lost here: the lateral segment of the RML need not touch the heart. Report what you see.
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Q2 What is your preferred diagnosis? Give one differential diagnosis.
Reveal answer
2 marks Interpretation
- Preferred: right middle lobe (lobar) pneumonia (1)
- Differential (1 mark): consolidation beyond an obstructing central tumour; accept pulmonary infarction or aspiration (1)
Examiner note RML collapse would show volume loss and a horizontal fissure displaced downwards.
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Q3 How would you confirm the location, and what follow-up imaging is appropriate?
Reveal answer
3 marks Management/Safety
- Lateral CXR: opacity between the horizontal and oblique fissures, projected over the heart (1)
- CT is not routine; keep it for non-resolution, complications (empyema, abscess) or suspected obstruction (1)
- Follow-up CXR at about 6 weeks if symptoms persist or malignancy risk is higher (smoker, age > 50) (BTS 2009) (1)
Examiner note Severity scoring (SMART-COP in Australia, CURB-65) and Therapeutic Guidelines antibiotics belong to the treating team, but know the terms.
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Q4 Explain the silhouette sign and how it localises disease in the right lung.
Reveal answer
2 marks Applied sciences
- Loss of a normal interface when two structures of similar (soft-tissue/fluid) density are in anatomical contact (Felson 1950) (1)
- The right heart border lies against the RML (medial segment) and the right hemidiaphragm against the RLL, so loss of each localises to that lobe; a preserved border means no contact (1)
Examiner note Left side: left heart border = lingula; left hemidiaphragm = LLL; aortic knuckle = apicoposterior LUL / superior LLL.
End of the OSCER block (10 marks).
Beyond the exam: teaching extension
Q5–Q9: not part of the 10-mark OSCER block. Untimed, viva-style discussion: mimics and pitfalls, complications, guidelines and report wording.
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Q5 Name the lobar collapse patterns on a frontal CXR. (The 2026 S1 OSCER report flags lobar collapse as a weak area.)
Reveal answer
- RUL: elevated horizontal fissure, upper-zone opacity; reverse S sign of Golden with a hilar mass
- RML: loss of the right heart border, horizontal fissure displaced down; thin wedge on the lateral
- RLL: triangular opacity behind the right heart, medial right hemidiaphragm lost, right heart border preserved
- LUL: hazy 'veil' over the left hemithorax; luftsichel sign (aerated superior segment of the LLL against the aortic arch)
- LLL: 'sail' triangle behind the heart, medial left hemidiaphragm lost, left hilum depressed
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Q6 What is the pathology of lobar pneumonia, and why do air bronchograms appear?
Reveal answer
- Classic stages: congestion, red hepatisation, grey hepatisation, resolution
- Alveoli fill with exudate while the conducting airways stay aerated, so air bronchograms appear
- Commonest organism: Streptococcus pneumoniae; think of Legionella, Staphylococcus aureus and Klebsiella in severe disease
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Q7 Which complications should imaging look for?
Reveal answer
- Parapneumonic effusion and empyema: ultrasound and sample; pleural fluid pH < 7.2 supports drainage (BTS 2023)
- Cavitation, lung abscess, necrotising pneumonia
- ARDS and sepsis; bronchopleural fistula (rare)
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Q8 Pitfalls: when should consolidation not be called 'just pneumonia'?
Reveal answer
- Radiographic resolution lags behind clinical recovery, often by weeks, and longer in older patients
- Non-resolving consolidation: think of obstructing carcinoma, invasive mucinous adenocarcinoma, lymphoma, organising pneumonia; arrange CT
- Round pneumonia in children can mimic a mass
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Q9 Draft the key sentences of your report.
Reveal answer
- 'Right mid-zone airspace consolidation bounded above by the horizontal fissure, consistent with right middle lobe pneumonia in this clinical setting. No effusion.'
- 'Suggest a follow-up radiograph at about 6 weeks to confirm resolution.'
End of questions. Reveal the diagnosis, key takeaways and syllabus mapping below.
Reveal diagnosis, key takeaways & syllabus mapping
Diagnosis Right middle lobe pneumonia
Key takeaways
- Localise with fissures and silhouettes, but report what you see: a preserved border does not exclude that lobe.
- The lateral film confirms the lobe; CT is for complications or non-resolution.
- Follow-up CXR at about 6 weeks in smokers or those over 50 (BTS 2009).
- Know all five lobar collapse patterns cold.
Syllabus mapping
| OSCER station | Thoracic and Cardiovascular |
|---|---|
| Learning Outcomes section | §6.5 Cardiothoracic |
| Appendix 1 condition | Pneumonia (lobar/bronchopneumonia) including community-acquired (Appendix 1 E, Infection/inflammatory conditions, p70) |
| Category | Category 1 |
| Key Condition | Yes |
| Core marks by domain | Observation 3 · Interpretation 2 · Management/Safety 3 · Applied sciences 2 (= 10) |
| Learning objectives | Localise consolidation with fissures and the silhouette sign; Choose appropriate follow-up and further imaging; Know lobar collapse patterns and complications |
Mapped to the RANZCR Clinical Radiology Learning Outcomes v1.3 (January 2024), section 6 and Appendix 1.
Further reading
- Felson B, Felson H. Localization of intrathoracic lesions by means of the postero-anterior roentgenogram; the silhouette sign. Radiology. 1950;55(3):363–374. PMID 14781343.
- Lim WS, Baudouin SV, George RC, et al. BTS guidelines for the management of community acquired pneumonia in adults: update 2009. Thorax. 2009;64(Suppl 3):iii1–iii55. PMID 19783532.
- Franquet T. Imaging of pneumonia: trends and algorithms. Eur Respir J. 2001;18(1):196–208. PMID 11510793.
- Charles PG, Wolfe R, Whitby M, et al. SMART-COP: a tool for predicting the need for intensive respiratory or vasopressor support in community-acquired pneumonia. Clin Infect Dis. 2008;47(3):375–384. PMID 18558884.
- Lim WS, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax. 2003;58(5):377–382. PMID 12728155.
- Therapeutic Guidelines Limited. Therapeutic Guidelines: Antibiotic (current version, eTG complete). Melbourne: Therapeutic Guidelines Ltd.
- Roberts ME, Rahman NM, Maskell NA, et al. British Thoracic Society Guideline for pleural disease. Thorax. 2023;78(Suppl 3):s1–s42. PMID 37433578.
- RANZCR. Clinical Radiology Learning Outcomes, v1.3 (January 2024), §6 and Appendix 1. Sydney: RANZCR.
- RANZCR. Clinical Radiology Phase 2 OSCER Sample Questions, v1.6 (4 May 2026). Sydney: RANZCR. (Format reference only; no RANZCR images reproduced.)
Always check current Australian/local guidelines.
Image credits
- A by Mikael Häggström, M.D., CC0, via Wikimedia Commons. Changes: resized and re-encoded (WebP/JPEG). Teaching arrows and labels are a separate overlay added by this site.
Original file titles are listed on the image credits page (they may reveal the diagnosis).