tuberculosis viral infections mediastinum radiology
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tuberculosis viral infections mediastinum radiologyTRANSCRIPT
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