Congenital Anomalies

Slide 1 · Congenital anomalies of the lung

Developmental defects, pulmonary morphology, and clinical presentation

Pulmonary hypoplasia · Foregut cysts · Pulmonary sequestration

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Relate normal foregut-derived lung development to congenital pulmonary anomalies.

Explain the mechanisms and neonatal implications of pulmonary hypoplasia.

Recognize the locations and airway-type histology of foregut cysts.

Distinguish intralobar from extralobar pulmonary sequestration.

Interpret anatomy, developmental mechanism, pathology, and typical presentation as one connected problem.

Slide 3 · Organize congenital lung anomalies by the defect

Pulmonary hypoplasia: Inadequate lung development with reduced lung size.

Foregut cyst: Abnormal developmental detachment producing a cystic structure.

Pulmonary sequestration: Noncommunicating lung tissue with systemic arterial supply.

Other lesions include airway, vascular, cystic, and lobar inflation anomalies.

Slide 4 · Embryologic origin: The respiratory diverticulum

Ventral primitive foregut

Respiratory outgrowth

Paired lung buds

Right: 3 lobar bronchi

Left: 2 lobar bronchi

Developmental map condensed p. 613.

Slide 5 · Foregut origin explains shared airway phenotypes

The respiratory system develops as an outgrowth of the ventral primitive foregut.

The tracheal outgrowth produces paired lung buds and a branching bronchial tree.

Abnormal separation or detachment can leave foregut-derived cystic structures.

Embryologic origin helps interpret a bronchogenic cyst with mature airway-wall elements.

Slide 6 · Normal airway branching: Proximal to distal

Trachea

Lobar bronchi

Small airways

Acinus

Alveolar ducts → alveolar sacs → gas-exchange alveoli

Slide 7 · Normal lung architecture: What must develop?

Conducting airways connect the trachea and bronchi with distal bronchioles.

Terminal bronchioles lead to acini containing respiratory bronchioles, ducts, and alveoli.

Alveoli are the structural site of air–blood gas exchange.

A developmental anomaly may primarily alter lung size, airway connection, or vascular supply.

Slide 8 · Airway-wall histology is a diagnostic reference

Bronchi have a cartilage-supported wall and ciliated respiratory epithelium.

Airway-associated glands produce mucus and contribute to mucosal defense.

Smooth muscle is a normal airway-wall constituent.

These same tissue components help identify bronchogenic cysts histologically.

Slide 9 · Alveoli: The functional endpoint of development

Ventilated alveoli

Thin alveolar septum

Capillary blood

Type I pneumocytes provide broad exchange surface; Type II cells make surfactant

Slide 10 · Two circulation concepts relevant to malformations

Normal airways are accompanied by a pulmonary and bronchial arterial supply.

Pulmonary sequestration is defined instead by anomalous arterial supply from the aorta or its branches.

A vessel’s origin therefore helps distinguish a sequestered region from normal lung.

Blood-supply abnormalities and airway-connection abnormalities are separate diagnostic observations.

Slide 11 · Three defining abnormalities

Anomaly

Primary defining feature

What to verify

Hypoplasia

Reduced developmental lung size

Laterality and impairment of expansion

Foregut cyst

Developmental cyst from foregut detachment

Location and epithelial / wall phenotype

Sequestration

Separate lung tissue without airway connection

Anomalous aortic arterial supply

Slide 12 · Pulmonary hypoplasia: Definition

Pulmonary hypoplasia is a developmental defect that reduces lung size.

Both lungs may be affected, even when one is more severely involved.

The core abnormality is underdevelopment rather than collapse of an originally fully developed lung.

Severe disease has major consequences in the early neonatal period.

Slide 13 · Reduced lung size is the morphological hallmark

Normal-sized lung

Hypoplastic lung

Conceptual size contrast; Not a scaled anatomical depiction

Slide 14 · Pulmonary hypoplasia may be asymmetric

The source describes a defect of development involving both lungs.

Severity need not be equal: One lung may be more affected than the other.

Asymmetry should not obscure the systemic embryonic or mechanical setting.

Clinical interpretation begins by evaluating whether fetal lung expansion was restricted.

Slide 15 · Restricted fetal expansion is the causal theme

Pulmonary hypoplasia can follow abnormalities that compress the developing lung.

A different route is impaired ability of the lung to expand in utero.

Both mechanisms act before the transition to neonatal respiration.

The developmental timing explains why severe deficits may be evident immediately after birth.

Slide 16 · Pathway from in-utero constraint to small lungs

Mechanical constraint

Impaired fetal expansion

Reduced lung development

Causal schematic; Precise molecular pathway is not specified in the source.

Slide 17 · Congenital diaphragmatic hernia and hypoplasia

Congenital diaphragmatic hernia is a cited cause of fetal lung compression.

The abnormal thoracic mechanical environment limits lung expansion.

The resulting developmental deficit produces pulmonary hypoplasia.

The lecture focuses on pulmonary consequences; Detailed hernia classification is outside this source excerpt.

Slide 18 · Compression-associated hypoplasia

Diaphragmatic hernia

Compression of fetal lungs

Pulmonary hypoplasia

The diagram shows the textbook’s compression mechanism at the organ level.

Slide 19 · Oligohydramnios-associated hypoplasia

Oligohydramnios is the second named setting for pulmonary hypoplasia.

It interferes with fetal lung expansion in utero.

The pathological endpoint is reduced lung size.

The causal lesson is inadequate physical expansion during development, not an acquired alveolar collapse.

Slide 20 · Restricted-expansion pathway

Oligohydramnios

Limited fetal expansion

Pulmonary hypoplasia

Slide 21 · Two cited settings, one developmental endpoint

Context

Perturbation

Shared consequence

Diaphragmatic hernia

Fetal lung compression

Reduced lung development

Oligohydramnios

Impeded fetal expansion

Reduced lung development

Slide 22 · Why severe hypoplasia is life-threatening

A normally developed lung provides alveolar surface for exchange between air and blood.

Severely underdeveloped lungs cannot provide adequate respiratory function after birth.

Severe pulmonary hypoplasia is fatal in the early neonatal period.

This is a severity statement; The text does not provide quantitative risk or survival estimates.

Slide 23 · Developmental hypoplasia versus acquired atelectasis

Hypoplasia: Defective fetal development leading to small lungs.

Atelectasis: Incomplete neonatal expansion or collapse of previously inflated lung.

The former reflects development; The latter describes an expansion / collapse state.

Do not use the two terms interchangeably without analyzing the anatomical and temporal context.

Slide 24 · Hypoplasia and atelectasis: Conceptual distinction

Feature

Pulmonary hypoplasia

Atelectasis

Primary process

Developmental undergrowth

Incomplete expansion or collapse

Core change

Reduced developed lung size

Poor aeration / reduced expansion

Timing

Established in utero

May occur in neonatal or later life

Clinical use

Analyze prenatal constraint

Analyze airway, pleura, or scarring

Slide 25 · Case interpretation: Small neonatal lungs

A newborn has severe respiratory compromise and markedly small lungs.

A history of diaphragmatic hernia would support developmental pulmonary hypoplasia.

Intrauterine restriction of lung expansion explains the structural deficit.

Question for learners: What additional prenatal context could produce the same endpoint?

Answer: Oligohydramnios is another cited causal context.

Slide 26 · Foregut cysts: Developmental origin

Foregut cysts arise when a part of the primitive foregut detaches abnormally.

The misplaced detached tissue may retain a recognizable foregut-derived wall phenotype.

These lesions differ conceptually from inadequate growth of the entire lung.

Classification depends on the histological architecture of the cyst wall.

Slide 27 · Mechanism of a foregut-derived cyst

Primitive foregut

Abnormal tissue detachment

Foregut cyst

The diagram is a developmental schematic, not a microscopic specimen.

Slide 28 · Foregut cysts: Typical anatomic sites

Middle mediastinum

Pulmonary hilum

Frequent sites of foregut cysts

Slide 29 · Hilum and middle mediastinum: Location matters

The hilum and middle mediastinum as the most frequent sites.

These regions contain major airways and other structures that may be compressed.

The clinical consequences can reflect location rather than aggressive intrinsic growth.

Anatomic location is supportive but cannot replace cyst-wall assessment.

Slide 30 · Foregut cysts: Wall-based classification

Type

Classification basis

Relative frequency in excerpt

Bronchogenic

Airway-like histologic wall

Most common

Esophageal

Esophageal-type wall

Not quantified

Enteric

Enteric-type wall

Not quantified

Slide 31 · Bronchogenic cyst: The reference phenotype

Bronchogenic cyst is the most common type of foregut cyst in the Robbins passage.

Its epithelial lining is ciliated pseudostratified columnar epithelium.

The wall contains bronchial glands, cartilage, and smooth muscle.

Together these features reproduce normal bronchial microanatomy.

Slide 32 · A bronchogenic cyst rarely joins the airway tree

The source states that bronchogenic cysts are rarely connected to the tracheobronchial tree.

A cyst can therefore be lined by respiratory epithelium without being an airway segment.

Airway connection and epithelial differentiation are distinct anatomical features.

This distinction becomes important when comparing a cyst with sequestration.

Slide 33 · Respiratory epithelial lining: Histologic clue

The characteristic lining is ciliated pseudostratified columnar epithelium.

“Pseudostratified” describes nuclei at different levels in one epithelial layer.

Cilia support recognition of respiratory-type epithelial differentiation.

The lining must be interpreted together with the rest of the cyst wall.

Slide 34 · Cyst-wall glands: Recapitulation of a bronchus

Bronchial glands are part of the bronchogenic cyst wall.

Normal bronchi contain mucus-producing subepithelial glands.

Glandular structures provide another correspondence between cyst and airway wall.

The combination of features is more informative than any one wall element alone.

Slide 35 · Cartilage is a critical wall component

Bronchogenic cysts can contain cartilage within their walls.

Cartilage is also part of the normal bronchial supporting framework.

Its presence helps explain why the lesion resembles bronchial rather than alveolar tissue.

Cartilage must be assessed in its histologic context with epithelium and glands.

Slide 36 · Smooth muscle completes the airway-wall pattern

The wall of a bronchogenic cyst may include smooth muscle.

Smooth muscle is normally found in conducting airway structures.

Glands, cartilage, and smooth muscle collectively mirror bronchial anatomy.

The cyst by its wall structure, not by symptoms alone.

Slide 37 · Bronchogenic cyst: Layered wall structure

Cyst lumen

Airway-type lining

Glands, cartilage, smooth muscle

Schematic cross-section—not a micrograph

Slide 38 · Four recognizable bronchogenic cyst components

Ciliated airway epithelium

Subepithelial glands

Cartilage + smooth muscle

A bronchogenic cyst reproduces these airway-wall elements

Slide 39 · Foregut cysts may be incidental

Many foregut cysts are found without causing symptoms.

Incidental presentation does not change their developmental origin.

In an asymptomatic lesion, location and wall architecture remain central to classification.

The source does not give a numerical probability of incidental detection.

Slide 40 · Compression produces symptomatic foregut cysts

Cysts can become symptomatic through pressure on neighboring structures.

The hilum and middle mediastinum place them near major airway-related structures.

The symptom mechanism is mechanical rather than necessarily infectious.

Clinical features alone do not uniquely establish a bronchogenic cyst phenotype.

Slide 41 · Superimposed infection: A second symptom mechanism

Foregut cysts can also present following superimposed infection.

Infection is a complication of a pre-existing developmental structure.

Compression and infection are separate mechanisms of symptomatic presentation.

The textbook passage does not specify organisms, laboratory thresholds, or treatment regimens.

Slide 42 · Foregut cyst presentation: Two mechanisms

Finding

Mechanical pathway

Infective pathway

Pre-existing lesion

Congenital foregut cyst

Congenital foregut cyst

Added event

Compression of nearby structures

Superimposed infection

Interpretation

Symptoms depend on site / pressure

Symptoms follow secondary infection

Slide 43 · Case interpretation: Mediastinal cyst

A cystic lesion near the middle mediastinum is discovered incidentally.

Its wall contains ciliated pseudostratified epithelium, cartilage, glands, and smooth muscle.

The combined findings support a bronchogenic cyst.

Question: Would the lack of airway communication exclude the diagnosis?

Answer: No. Bronchogenic cysts are rarely connected to the airway tree.

Slide 44 · Sequestration: Two-part definition

Pulmonary sequestration is a discrete mass or area of lung tissue.

There is no connection to the normal airway tree.

Its arterial supply arises anomalously from the aorta or its branches.

The two diagnostic components are airway isolation and systemic arterial inflow.

Slide 45 · Two defining findings in pulmonary sequestration

Sequestered tissue

No airway connection

Aorta or its branches

Two defining criteria must coexist

Aberrant systemic arterial supply

Slide 46 · Why absent airway connection matters

Sequestered tissue does not communicate with the tracheobronchial tree.

The absent connection separates it anatomically from ordinarily ventilated lung.

This is a defining criterion rather than a secondary feature of infection.

A disconnected airway segment alone is insufficient without the abnormal arterial supply.

Slide 47 · Abnormal arterial origin is indispensable

Blood supply is derived from the aorta or one of its branches.

This is not the ordinary pulmonary arterial arrangement of lung parenchyma.

The artery’s origin is part of the definition, not merely an associated finding.

Anatomic evaluation should establish both blood supply and airway connection.

Slide 48 · Airway and blood supply define different axes

Airway anatomy asks whether tissue connects to a patent tracheobronchial pathway.

Vascular anatomy asks where arterial inflow originates.

Pulmonary sequestration is defined by an abnormality in both axes.

Its location relative to the surrounding lung determines the intralobar / extralobar subtype.

Slide 49 · Extralobar versus intralobar location

Extralobar: Outside the lung

Intralobar: Within the lung

Schematic location only—not anatomical imaging

Slide 50 · Extralobar sequestration: Outside the lung

Extralobar sequestration is located external to the lung.

It is an anatomically separate focus of lung tissue.

It still meets the shared criteria: No airway connection and aortic-derived arterial supply.

The extralobar descriptor states its location, not a different embryologic cell type.

Slide 51 · Extralobar sequestration: Infant mass lesion

Extralobar lesions most often present in infants.

The typical described presentation is as a mass lesion.

An early mass presentation differs from later infectious manifestations of intralobar lesions.

These are tendencies in the passage; Precise age limits or frequencies are not supplied.

Slide 52 · Extralobar lesions and other anomalies

Extralobar sequestration may coexist with other congenital abnormalities.

A concurrent malformation should not be assumed to cause sequestration.

The coexistence is clinically important when interpreting complex congenital presentations.

The source does not enumerate specific associated defects or their frequencies.

Slide 53 · Intralobar sequestration: Within lung parenchyma

Intralobar sequestration is located within the lung.

Unlike the extralobar form, it is not an external mass of tissue.

It retains the basic sequestration features of airway separation and systemic artery.

The “intra-” versus “extra-” distinction describes position relative to lung.

Slide 54 · Intralobar sequestration tends to present later

Presentation most often in older children.

Repeated localized infections are a common reason for recognition.

Bronchiectasis is another presenting association noted in the source.

A later symptomatic presentation does not negate a congenital structural origin.

Slide 55 · Recurrent localized infection: An anatomic clue

Intralobar sequestration is associated with recurrent localized infection.

Localization is a clue to a persistent focal anatomic abnormality.

Repeated episodes can prompt consideration of a congenital malformation.

A complete sequestration interpretation must still establish airway and vascular anatomy.

Slide 56 · Bronchiectasis is a documented association

Bronchiectasis is named as a presentation of intralobar sequestration.

It signifies an airway-damage pattern rather than defining sequestration itself.

A localized bronchiectatic process can coexist with sequestered lung tissue.

The supplied source does not describe the detailed microscopic progression.

Slide 57 · Presentation pattern: Extra- versus intralobar

Extralobar presentation

Intralobar presentation

Infancy / mass lesion

Older childhood / infection

Typical clinical patterns—not obligatory ages

Slide 58 · Sequestration subtypes: Structured comparison

Feature

Extralobar

Intralobar

Relationship to lung

External to lung

Within lung

Usual presentation

Infant mass lesion

Older child: Repeated local infection

Associated findings

May coexist with anomalies

Bronchiectasis may occur

Shared definition

Disconnected + systemic artery

Disconnected + systemic artery

Slide 59 · Why timing cannot substitute for anatomy

Infant mass lesions suggest the usual extralobar presentation.

Older childhood with localized infection suggests the usual intralobar presentation.

Age and symptoms are informative patterns, not the defining classification criteria.

Definitive conceptual distinction remains outside-versus-within lung tissue.

Slide 60 · Case interpretation: Recurrent focal infection

An older child has repeated infections affecting one localized lung region.

A congenital intralobar sequestration is a relevant explanatory possibility.

The anatomic questions are airway communication and systemic arterial origin.

Question: Does recurrent infection itself prove sequestration?

Answer: No. Both defining anatomic features must be established.

Slide 61 · Other congenital abnormalities: Scope of Robbins

Additional anomalies affect the trachea, bronchi, pulmonary vessels, and lung parenchyma.

The text names airway atresia, stenosis, and tracheoesophageal fistula.

It also lists vascular anomalies, congenital pulmonary airway malformation, and lobar overinflation.

This chapter passage does not expand their subtypes, histology, or treatment.

Slide 62 · Less common anomalies: Organ-system map

Anatomic domain

Named entities in the source

Nature of source detail

Conducting airways

Atresia; Stenosis; Tracheoesophageal fistula

Named only

Pulmonary vessels

Vascular anomalies

Named only

Lung development

Congenital pulmonary airway malformation

Named only

Lobar inflation

Congenital lobar overinflation (emphysema)

Named only

Slide 63 · Airway anomalies: Separate the named concepts

Atresia and stenosis are listed as tracheal or bronchial developmental anomalies.

Tracheoesophageal fistula is also listed within that airway group.

These entities should not be conflated with a bronchogenic cyst.

Robbins provides no detailed causal mechanism for these lesions in this paragraph.

Slide 64 · Vascular and parenchymal anomalies: Boundaries

Vascular malformations are included among less common congenital pulmonary defects.

Congenital pulmonary airway malformation is specifically named.

Congenital lobar overinflation, also called emphysema in the excerpt, is also named.

Specific clinical criteria and morphologic subtypes require material beyond this passage.

Slide 65 · Do not confuse congenital entities

Entity

Distinguishing source-defined point

Pulmonary hypoplasia

Reduced developmental size of lung tissue

Bronchogenic cyst

Foregut-derived cyst with characteristic airway-type wall

Pulmonary sequestration

Noncommunicating tissue + systemic artery

Lobar overinflation

Named separately; Mechanism not elaborated here

Slide 66 · Integrated classification: Ask three anatomical questions

Small developed lung?

Cyst near hilum / mediastinum?

Disconnected tissue + systemic artery?

Hypoplasia

Foregut cyst

Sequestration

Slide 67 · A disciplined congenital-lung diagnostic description

Start with the anatomical compartment: Lung tissue, airway, cyst, or vessel.

Record the developmental feature: Small lung, cystic separation, or isolated tissue.

If sequestration is considered, establish airway connection and arterial origin.

For cysts, interpret wall histology together with the mediastinal / hilar location.

Slide 68 · Case set: Distinguish three mechanisms

A newborn with a history of oligohydramnios has unusually small lungs.

An incidental hilar cyst has respiratory epithelium, glands, cartilage, and smooth muscle.

An older child has localized recurrent infection and an isolated region of lung tissue.

Match each pattern to the most defensible congenital anomaly.

Slide 69 · Case set: Reasoned answers

Pattern

Most consistent interpretation

Decisive source feature

Small lungs + oligohydramnios

Pulmonary hypoplasia

Restricted in-utero expansion

Hilar airway-type cyst

Bronchogenic cyst

Wall recapitulates bronchus

Focal infection + isolated tissue

Possible intralobar sequestration

Must also show systemic artery

Slide 70 · Five defensible take-home principles

Pulmonary hypoplasia represents reduced development, often after restricted fetal expansion.

Foregut cysts arise through abnormal detachment; Bronchogenic cysts reproduce an airway wall.

Sequestration requires both absent airway connection and abnormal aortic arterial supply.

Extralobar and intralobar forms differ in position and usual clinical presentation.

Other congenital anomalies are named but not detailed in this Robbins section.

Slide 71 · Reference and scope of this lecture

Robbins, Cotran & Kumar. Pathologic Basis of Disease. 11th ed. Chapter 15: The Lung.

Primary congenital anomalies section: printed page 613.

Normal lung development and histology: introductory material on page 613.

Acquired atelectasis contrasted only where it clarifies the developmental distinction.

Schematic figures are original editable teaching illustrations; no clinical specimen image is reproduced.