TuberculosisViral Infections Mediastinum

Dr Saket Kumar Jain (Resident)

Dept. Of Radio-DiagnosisMGM HOSPITAL

Tuberculosis

Two types – primary and post primary

Patients who develop disease after initial exposure are considered to have primary TB .

Primary site of infection in the lungs is called the Ghon focus.

The combination of the Ghon’s focus and affected lymph nodes is known as the primary complex .

“ Ranke complex ”

Parenchymal Primary Post-primary

Self limiting progressive

dense, homogeneous parenchyma consolidation in any lobe

patchy, poorly defined consolidation, particularly in the apical and posterior segments of the upper lobes

however, predominance in the lower and middle lobes is suggestive of the disease, especially in adults

 in majority- more than one pulmonary segment is involved, with bilateral disease seen in one-third to two-thirds of cases.

appearance is often indistinguishable from that of bacterial pneumonia

Patterns

Cavitations' primary Post primary

Rare Cavitation, the hallmark of postprimary tuberculosis

typically have thick, irregular walls, which become smooth and thin with successful treatment

Are multiple

Lymphadenopathy

is seen in up to 96% of children and 43% of adults

seen in only about 5% of patient

typically unilateral and right sided, involving the hilum and right paratracheal region

although it is bilateral in about one-third of cases

it can be the sole radiographic finding more common in infants and decreases in frequency with age

Pleural effusion Primary Post primary

seen in approximately one-fourth of patients

seen in approximately 18% of patients with postprimary tuberculosis

 often the sole manifestation of tuberculosis

usually small and associated with parenchymal disease

very uncommon finding in infants &  is usually unilateral

effusions are typically septated

Ranke complex

Parenchymal primary tuberculosis in an adult.

Miliary Tuberculosis Widespread hematogenous dissemination of 

Mycobacterium Tuberculosis

So named because the nodules are the size of millet seeds  (1mm to 3 mm)

Diffuse, random distribution

Takes weeks between the time of dissemination and the radiographic appearance of disease

When first visible, they measure about 1 mm in size; they can grow to 2-3mm if left untreated

HIV and TB No matter what form of TB the patient has, it

tends to look like 1° TB

Hilar and mediastinal adenopathy are common

Cavitation is less common

There is no predilection for the apices

Atypical mycobacterium( MAI - mycobacterium avium-intracellulare) is more common in HIV than Mycobacterium Tuberculosis

Differential DiagnosisSARCOIDOSIS HISTOPLASMOSIS

Consolidation Consolidation - ? acute pneumonia .

The term consolidation does not imply any particular aetiology or pathology .

Acute pneumonia is the commonest cause but not the only cause of consolidation --- ( other causes include chronic pneumonia, pulmonary oedema and neoplasm)

what is consolidation ?

Refers to fluid in the airspaces of the lung

Consolidation may be complete or incomplete

The distribution of the consolidation can vary widely. A consolidation could be described as “patchy”, “homogenous”, or generalized”.

A consolidation may be described as focal or by the lobe or segment of lobe affected

Pulonary edema (especially cardiogenic)pneumonia

Batwing sign

Consolidation - Differentials

Air bronchogram signAir bronchogram refers to the phenomenon of air-filled bronchi

(dark) being made visible by the opacification of surrounding alveoli (grey - white).

Viral infections Micro-organisms responsible may enter the lung by three potential

routes:

via the tracheobronchial tree

via the pulmonary vasculature

via direct spread from infection in the mediastinum, chest wall, or upper abdomen

Viral infections (DNA)INFLUENZA PARAINFLUENZA

Outbreaks in winter Risk in DM, Elderly, IC

In winterSelf limited

Dry cough, headache,myalgia, fever, croup and otitis media

Croup , coughing , dyspnea , wheezing , tonsilitis, pharyngitis

Superadded bact inf. Can occur In children with croup may show subglottic tracheal narowing so called STEEPLE sign

Multifocal patchy consolidation may be uni/bilateral

Multifocal patchy consolidation may be uni/bilateral

Plerual effusion uncommon

Influenza

RSV MEASLES (RUBEOLA)

Winter & spring Imp. Cause of both URTI &LRTI in infants & young children

Year round

In children-URTI- pharyngitis, rhinitis, otitis media

Fever, myalgia, headache, conjuctivitis cough

LRTI- coughing, dyspnea, wheezing, intercoastal retraction

Rhinorrhea followed by skin rash

Perihilar linear opacities , bronchial wall thickening, patchy areas of consolidation

B/L patchy air space consolidation associated in perihilar

In children-may be lymph node enlargement

RSV

Measles

RNA VIRUS

HERPES SIMPLEX-1 Affects oral cavity ,LRTI occurs if organism is transported into trachea & bronchi They are severly immunocompromised Multifocal consolidation due to bronchopneumonia

• Herpes simplex – 2 – acquired during child birth

Varicella zoster virus – pneumonia presents as high fever rapidly followed by skin rash Appear as diffuse small nodules in the range of 5-10 mm that progress to air space consolidation rather rapidly Hilar lymphadenopathy is common Pleural effusion is rare

MEDIASTINUM - Anatomy

It is the central compartment of the thoracic cavity

Contents of mediastinum

Anterior mediastinum

3 ; T’s

ThymusThyroidThoracic

aorta

Middle mediastinum

Heart surrounded by

the pericardiumgreat vessels :ascending aortasuperior vena

cavapulmonary trunk

Trachea bifurcation

Posterior mediastinum:

contents 

“DATES”:Descending

aortaAzygos and

hemiazygous veins

Thoracic ductEsophagus

Sympathetic trunk/ganglia

Felsons method of division -

Anterior, Middle, Posterior.

Diagnostic Evaluation RADIOLOGY

• Plain chest x-ray.

• CT of the chest ( procedure of choice for mediastinal masses )

• MRI (may enhance the diagnostic abilities of chest CT)

▪ FNA or needle biopsy with CT guidance .

Thymus – normal

A normal thymus is visible in 50% of pediatric age group of 0–2 years of age.

  The size and shape of the thymus are highly variable

The thymus is seen as a triangular sail (thymic sail sign) frequently towards the right of the mediastinum. It has no mass effect on vascular structures or airway.

THYMIC SAIL SIGN

Thymoma The most common neoplasm of the anterosuperior compartment

Radiograph: small, well-circumscribed mass or as a bulky lobulated mass confluent with adjacent mediastinal structures

Symptoms: • chest pain • dyspnea• hemoptysis• cough• superior vena cava syndrome • systemic syndromes caused by immunologic mechanisms

Retrosternal thyroid Enlarged thyroid usually are considered retrosternal (also referred to

as mediastinal, intrathoracic, or substernal) when more than 50% of the thyroid parenchyma is located below the sternal notch

Presentation - Substernal Goiters

Asymptomatic Choking sensation, particularly in supine position Vague chest pain or heaviness

Respiratory • Dyspnoea• Orthopnea• Cough• Respiratory

distress/insufficiency• Airway obstruction

Neural• Hoarseness• Hemidiaphragm

elevationEsophageal• Dysphagia• Odynophagia

Mediastinal lymphoma The mediastinum is commonly involved in lymphoma, either as

part of disseminated disease or less commonly as the site of primary involvement.

Symptoms retrosternal chest pain SVC Compression with SVC SYNDROME dyspnoea Cough

PLAIN FILM A soft tissue mass may be clearly visible, or more frequently the

mediastinum is widened, and the retrosternal space is obscured.

Foregut duplication cyst

This is a broad term used to encompass a number of congenital mediastinal cysts derived from the embryological foregut.

They include bronchogenic, esophageal duplication and neuroenteric cysts .

Bronchogenic cysts are the most common.

Bronchogenic cyst

Esophageal Duplication Cyst

Neurenteric cysts

Pericardial cystThese are congenital out-pouchings from the parietal pericardium

HIATUS HERNIA

Two types:Sliding(99%)Rolling/paraoesophageal(1%)

A hiatus hernia occurs where there is herniation of stomach through the esophageal hiatus of the diaphragm

SchwannomaSchwannomas are benign tumor's of Schwann cell origin and are the most common tumors of peripheral nerves.

Any cranial nerve may be involved, except CNI and CN2 which lack sheaths composed of schwann cells

CN VIII (acoustic neuroma) most commonly the superior portion of vestibular nerve (most common)CN V (2nd most common)CN VII (3rd most common)

Clinical presentationPresentation depends on location of the tumor.

Pneumomediastinum Pneumomediastinum is the presence of extra luminal gas within

the mediastinum. Gas may come from lungs, trachea, central bronchi, esophagus, and the neck or abdomen.

“Continuous diaphragm sign” of pneumomediastinum

spinnaker sign (also known as the angel wing sign)

TEACHING POINT

MEDIASTINUM - To diagnose a pathology , very difficult - complete work-up

HISTORY , X-RAY + further investigation

TUBERCULOSIS VERY COMMON – HIGH INDEX OF SUSPICION-

CLINICAL PRESENTATION

Its easy to diagnose consolidation but difficult to interpret it , correlation with clinical

symptoms is the key point