Lungs Fx Linear Atelectasis Dx Acute Asthma CT Coronal Projection
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Lungs
2. Findings and Diagnosis
CT Linear Atelectasis 3 Months Later
CT scan in the coronal plane 3 months later shows significant improvement of the atelectasis involving a basal segment of the left lower lobe associated with persistent elevation of the left hemidiaphragm indicating volume loss. The atelectasis now has a discoid, linear, or plate-like appearance
Ashley Davidoff MD TheCommonVein.net 276Lu 136238
aka discoid atelectasis aka plate-like atelectasis
PAGE 2 – FINDINGS
* Linear Atelectasis and Elevated Left Hemidiaphragm in Acute Asthma *
CT (coronal) shows discoid (linear, plate-like) subsegmental atelectasis in the left lower lobe with elevation of the ipsilateral hemidiaphragm. Findings are consistent with airway obstruction secondary to acute asthma exacerbation.
28-year-old female with known asthma presenting with acute respiratory symptoms.
Radiologic Findings Table
Observation
Description
Discoid (Linear) Atelectasis
Thin plate-like opacity in the posterior left lower lobe consistent with discoid atelectasis—a flat, segmental collapse due to mucus plugging.
Hemidiaphragm Elevation
Left hemidiaphragm elevated due to volume loss from subsegmental collapse
Distribution
Localized to left lower lobe; typical of gravity-dependent airway plugging
No Consolidation or Effusion
Supports a non-infectious, obstructive process
Differential Diagnosis
Most Likely Diagnosis Table
Diagnosis
Rationale
Acute Asthma
Known asthmatic with mucus plugging causing subsegmental collapse and diaphragm elevation
Other Considerations Table
Category
Diagnosis
Rationale
Infection
Viral bronchiolitis
Can cause mucus plugging but less likely without systemic signs
Mechanical
Foreign body aspiration
Uncommon at this age with no acute choking event
Neoplasm – Benign
Bronchial hamartoma
Rare and unlikely with acute presentation
Circulatory
Pulmonary embolism
Typically causes wedge-shaped opacity, not discoid collapse
Idiopathic
Idiopathic diaphragmatic event
No supporting history or imaging evidence
Key Points and Pearls Table
Pearl
Explanation
Discoid (Linear) Atelectasis = Mucus Plugging
In asthma, obstruction by thick mucus leads to reversible volume loss in dependent lung regions
Hemidiaphragm Elevation = Volume Loss
Elevation of diaphragm indicates collapse of underlying lung tissue
Asthma Without Infiltrate
Helps distinguish from infection, which would typically show consolidation
CT More Sensitive Than X-ray
Subtle atelectasis may be missed on plain radiograph
3. Clinical
PAGE 4 – INFO: Broader Clinical and Radiologic Context
Primary Focus: Linear (Discoid) Atelectasis
Table 1 – Broad Disease Context
Category
Details
Definition
Linear (discoid or plate-like) atelectasis is a form of partial lung collapse characterized by thin, curvilinear opacities—usually horizontal—in subsegmental lung regions.
Etiology
Most commonly caused by transient small airway obstruction due to mucus plugging. Other causes include hypoventilation, post-op effects, surfactant dysfunction, or compression.
Resulting Pathology
Air resorption distal to the obstruction leads to alveolar collapse and loss of aeration in a ribbon-like distribution.
Structural Changes
Collapsed alveoli and mild adjacent volume loss; the surrounding lung may be normal or mildly hyperinflated to compensate.
Functional Changes
Mild hypoventilation and ventilation-perfusion mismatch in the affected area; often reversible.
Clinical Diagnosis
Often asymptomatic but may be associated with asthma, post-surgical states, or sedation. Detected incidentally or via imaging for hypoxia.
Imaging Diagnosis
CT and CXR show thin, plate-like, linear opacities—typically in dependent zones (posterior or basal lobes), best seen on lateral views.
Laboratory Workup
Labs are usually normal unless underlying pathology (e.g., asthma, infection) is present.
Treatment Strategies
Treat underlying cause (e.g., bronchodilators for asthma); encourage deep breathing, coughing, incentive spirometry, or bronchoscopy if persistent.
Table 2 – Radiology Subtypes and Complications
Subtype / Pattern
Relevance to Linear Atelectasis
Discoid Atelectasis
Synonymous term; describes the shape and distribution on imaging—flat and linear
Subsegmental Atelectasis
Often used interchangeably; refers to focal collapse affecting small airway units
Basilar or Posterior Atelectasis
Common due to gravity and dependent positioning, especially in supine patients
Obstructive (Mucus Plug)
Common in asthma, post-op, or debilitated patients; most frequent reversible cause
Compression Atelectasis
Caused by adjacent mass effect or pleural effusion—not applicable in this case
Complications
Usually benign; if persistent, may indicate underlying chronic disease or lead to infection
Key Points and Pearls Table
Insight
Explanation
Common, often missed finding
Linear atelectasis is subtle and may be overlooked, especially on supine chest X-rays
Reversible and benign
Most cases resolve with airway clearance and treating the underlying cause
Best seen in dependent regions
Posterior lower lobes in supine patients; lateral and coronal CT views are most sensitive
Associated with asthma
Mucus plugging during exacerbations is a key cause—volume loss explains ipsilateral diaphragm elevation
May mimic more serious pathology
Can be confused with scarring or early consolidation—clinical context is essential
4. Historical and Cultural
PAGE 5 – OTHER: Historical and Cultural Dimensions
Primary Focus: Linear (Discoid) Atelectasis
Table 1 – Cultural Reflections on Radiologic Units and Diagnosis
Radiologic Term
Etymology / Historical Note
Atelectasis
From Greek atelēs (incomplete) and ektasis (expansion). Term introduced in the early 19th century to describe lung collapse.
Discoid Atelectasis
The term “discoid” refers to its flat, plate-like radiologic shape—commonly recognized on portable chest X-rays since mid-20th century.
Linear Opacity
Describes the radiologic appearance—a thin, elongated density often aligned with gravitational dependency.
Table 2 – Medical History Related to Disease
Topic
Historical Significance
First Use of “Atelectasis”
First coined by Laennec (1819), who described localized lung collapse on autopsy and auscultation.
Recognition of Discoid Pattern
Identified radiographically in post-op patients and bedbound individuals as early as the 1950s.
Association with Asthma and Mucus
Mucus plugging as a reversible cause was histologically documented in the 20th century, with CT confirming patterns.
CT Validation
The flat, dependent opacities were confirmed as reversible on CT in asthma, post-op states, and sedation settings.
Table 3 – Arts and Humanities (Alphabetical)
Discipline
Reflection of Collapse, Volume Loss, and Subtlety
Dance
The collapse of movement or posture in dance can reflect the involuntary collapse seen in atelectasis.
Literature
Concepts of internal collapse—emotional, spiritual, or physical—mirror the silent nature of linear atelectasis.
Music
Pauses and silences in music can represent absence or withdrawal of force—like collapsed lung tissue.
Painting
Minimalist or compressed forms echo the reduced volume and subtle lines of linear atelectasis on imaging.
Sculpture
Flattened or concave forms may metaphorically reflect compression or collapse in physical and emotional states.
Table 4 – Notable Individuals with Related Conditions
Name
Field
Comment
Theodore Roosevelt
Politics
Suffered from childhood asthma; may have experienced transient collapse from mucus plugging.
Diane Keaton
Acting
Has discussed asthma and breathing-related challenges.
Joaquin Phoenix
Acting
Uses an inhaler for asthma; at risk for transient atelectasis during exacerbations.
5. MCQs
PAGE 6 – MULTIPLE CHOICE QUESTIONS (MCQs)
Primary Subject: Linear (Discoid) Atelectasis Underlying Cause: Asthma (where relevant)
Question 1 (Basic Science)
What is the most common pathophysiologic mechanism leading to linear (discoid) atelectasis?
A. Hypoxic pulmonary vasoconstriction B. Surfactant deficiency C. Obstruction of small airways by mucus D. Pleural effusion compressing lung parenchyma
Correct Answer and Explanation Table
Correct Answer
Explanation
C. Obstruction of small airways by mucus
Mucus plugging leads to resorption of trapped air distal to the obstruction, causing localized alveolar collapse.
Incorrect Answer Rationale Table
Option
Why Incorrect
A
Refers to vascular shunting, not a cause of collapse.
B
Seen in neonatal RDS; not typical in asthma or most adult atelectasis cases.
D
Causes compression atelectasis, not linear (discoid) pattern.
Question 2 (Basic Science)
Which of the following is most characteristic of the histologic appearance of atelectatic lung tissue?
A. Hypercellular alveolar walls with hyaline membranes B. Collapsed alveoli with minimal inflammation C. Caseating granulomas in terminal bronchioles D. Widened interlobular septa with lipid-laden macrophages
Correct Answer and Explanation Table
Correct Answer
Explanation
B. Collapsed alveoli with minimal inflammation
In simple atelectasis (as seen in linear types), the alveoli are collapsed but histologically intact.
Incorrect Answer Rationale Table
Option
Why Incorrect
A
Characteristic of ARDS, not simple atelectasis.
C
Seen in tuberculosis.
D
Seen in lipoid pneumonia, not atelectasis.
6. Memory Image
PAGE 7 – MEMORY IMAGE
Linear Atelectasis of some Middle Floors in a High Rise
Loss of Height
Compensatory Overgrowth of Base
Restortion of Height
Discoid Atelectasis Artistic rendering shows high rise (a normal) alongside a neighboring structure with collapse of mid floors (b) representing segmental volume loss, and compensatory overgrowth (c) restoring height — a metaphor for discoid atelectasis and reactive hyperinflation. Courtesy: Ashley Davidoff MD, TheCommonVein.com (140519.8 lungs linear atelectasis discoid)