Pulmonary Tuberculosis

The most common hematologic findings are mild anemia, leukocytosis, and thrombocytosis with a slightly elevated erythrocyte sedimentation.

Reference:
Harrisons Principles of Internal Medicine, 18th Edition, Page 1346

Ans. is ‘a’ i.e., Lungs

• Secondary TB is due to reactivation and involves Lung particularly the apical and posterior segments of upper lobe.

Ans. is ‘b’ i.e., Secretory

Epitheloid cells are activated macrophages and the function of macrophages is phagocytosis

So do ‘nt be misled into wrong conclusion that the most important function of epitheloid cells is phagocytosis. Epitheloid cells appear to have enhanced abilities to secrete lysozyme and a variety of enzymes but decreased phagocytosis potential.

The abundant pale cytoplasm reflects the presence of extensive rough endoplasmic reticulum (secretory function). –

Answer is A (Cavitatory lesion):

Cavitatory lesions are a feature of post primary or secondary tuberculosis and not primary tuberculosis cases Cavitation is rare in primary tuberculosis

Cavitation is a feature of secondary Tuberculosis (Robbins)

Cavitation occurs readily in the secondary form.

Indeed cavitation is almost inevitable in neglected secondary tuberculosis. Cavitation may be seen in primary tuberculosis but it is a rare feature. – Robbins

Fibrocasseous lesion are charachteristic in primary Tuberculosis

The charachteristic pulmonary lesion in primary tuberculosis is a Ghon’s focus, which is in fact a fibrocasseous lesion showing marked granulomatous inflammatory reaction with casseous necrosis.

Phlectenular conjunctivitis is a feature of primary tuberculosis

Phlyctenular conjunctivits is a hypersensitivity reaction in the eye to the presence of TB bacilli elsewhere in the body. It is commonly seen in children with primary tuberculosis

The onset of tubercular infection may be accompanied by erythema nodosum or phlyctenular conjunctivitis which are regarded as hypersensitivity reactions to mycobacteria. These lesions reflect tuberculin conversion in primary tuberculosis

Hallmarks indicating Hypersensitivity to Mycobacteria in Primary pulmonary TB

• Erythema nodosum
• Phlyctenular conjunctivitis

Pleural effusion is common in primary tuberculosis

`Pleural effusion is found in upto 2/3 of cases of primary tuberculosis and results from penetration of bacilli into the pleural space from an adjacent subpleural focus’ – Harrison

Answer is D None (All may be seen )

All features mentioned may be seen in the normal course of a primary tuberculous infection.

Pleural effusion may be seen in primary tuberculosis

Pleural effusion is found in upto 2/3 of cases of primary tuberculosis and results from penetration of bacilli into the pleural space from an adjacent subpleural focus’ – Harrison

Answer is A (Lungs):

The most common primary site for primary tuberculosis is the Lung.

‘Primary site is the Lung in upto 95% of cases’ – Oski’s Pediatrics

‘For both primary and reactivation tuberculosis the lungs are the most commonly affected site.’

Most common primary site for Primary Tuberculosis is LungsQ

Most common site for Post-Primary Reactivation Tuberculosis is Lune Most common primary site for congenital tuberculosis is Liver°

Most common site /organ involved in congenital tuberculosis in Lune

Principles of Pulmonary Medicine (Elsevier) 547107

Primary tuberculosis:

• It is the first infection with tubercle bacilli in individuals who have not been previously exposed to the organisms
• Seen in children Q
• Primary complex is characteristic

Primary (Ghon) complex

• Unilateral enlarged hi lar lymph nodes Q
• Ghon focus Epitheloid-cell granulomatous inflammation (consolidation) at site of parenchymal infection. Usually small and subpleural most commonly located under pleura in lower part of upper lobe
• Usually a symptomatic ^Q or manifested by a mild tlu like illness at time of tuberculin conversion
• Lesion heal by fibrosis ^Q and may calcify Q
• Radiological evidence of healed primary infection may or may not be present Q

Effects of primary tuberculosis

• Tuberculin positivity Q                                                                                                                                                            
• Partial immunity to tuberculosis^Q: individual requires a higher dose to be reinfected by tubercle bacilli
• Presence of dormant tubercle bacilli

Ans. Answer is B (Liver):

Most common primary site- LIVER (primary complex in liver is suggestive of congenital TB)

Most common site is- LUNG

The form of disease is usuall^y miliary with multiple organ involvement. Lungs are involved in almost all cases. Other sites frequently involved are liver, spleen, l^ymph nodes, the gastrointestinal tract and kidney’.

-Textbook of Pulmonary Medicine by Behera 2″a/495

Answer is A (Pulmonary tuberculosis):

All features mentioned in this question are in favour of pulmonary tuberculosis and the only feature that troubles is a ‘negative sputum cytology’. A negative sputum cytology however does not rule out pulmonary tuberculosis. ‘A negative sputum cytology does not rule out pulmonary tuberculosis’- CMDT

`There is a definite set for patients of ‘suspected TB with negative sputum smears’. These patients are usually investigated by bronchoscopy as the next diagnostic step. Bronchial washings and transbronchial lung biopsies are specially helpful and increase the diagnostic yield’. – CMDT

Definitive diagnosis of TB :

Does not depend on sputum cytology but, it depends on recovery of Mycobacterium TB in cultures or identification of organism by DNA probe.

Remember: “demonstration of acid fast bacilli on sputum smears does not confirm a diagnosis of TB”.

Since saphrophytic and non tuberculous mycobacteria make colonize the airways or cause pulmonary disease. It is sputum culture with demonstration of M. TB that is diagnostic.

Answer is B (Tuberculosis) :

Most common cause of necrotic lymph nodes with peripheral rim enhancement is tuberculosis.

• Peripheral rim enhancement is seen in most granulomatous lymphadenopathies.

Most common cause of necrotic lymph nodes with peripheral rim enhancement is Tuberculosis

– In tuberculosis affected lymph nodes show relatively low attenuation of their central region and peripheral rim

enhancement after I.V. contrast material

– In Sarcoidosis lymph nodes are not necrotic and calcification is uncommon

• Expectoration is a major manifestation in tuberculosis.

It is usually not associated sarcoidosis, silicosis and lymphoma.

• Cough and bilateral upper lobe fibrosis makes lymphoma unlikely. It may be seen in the other conditions.

The only condition satisfying all the clinical features mentioned in the question is tuberculosis and hence is the answer of choice.

Answer is B (Tuberculosis) :

Most common cause of necrotic lymph nodes with peripheral rim enhancement is Tuberculosis.

Ans: B i.e. Apex of lungs

Secondary pulmonary TB classically involves the apex of the upper lobes of one or both the lungs

Progressive primary TB more often resembles an acute bacterial pneumonia, with lower and middle lobe consolidation, hilar adenopathy, and pleural effusion; cavitation is rare.

Ans. A: Apical lung cavity

In overwhelming majority of cases primary complex occurs in the lungs and only in about 5% cases they are distributed among the intestines, Oropharynx, the skin and other rarer sites. The primary focus in the lungs is called as Ghon focus. It generally occurs in the subpleural region of midline and lower lung zones. Mostly hilar and inter-pleural lymph nodes are involved to form the primary complex.

Secondary TB is usually localized to apical and posterior segment of upper lobes.

Ans. D: Apex of the upper lobe

Secondary pulmonary tuberculosis classically involves the apex of the upper lobes of one or both the lungs

Secondary tuberculosis

• It is usually due to the reactivation of old lesions or gradual progression of primary tuberculosis into chronic form.
• The characteristics of secondary tuberculosis include extensive tissue damages due to immunologic reactions of the host to tubercle bacilli and their products.

Primary vs Secondary Tuberculosis

• When a host has first contact with tubercle bacilli:

– An acute exudative lesion develops and rapidly spreads to the lymphatics and regional lymph nodes.

– The exudative lesion in tissue often heals rapidly.

– The lymph node undergoes caseation, which usually calcifies.

– The tuberculin test becomes positive.

• If the primary lesion could not contained rapidly, the appearance of hypersensitivity to tuberculin provokes a dramatic change in the host’s response to the organisms.
• The nonspecific inflammatory response evoked on first exposure to tubercle bacilli becomes granulomatous, evoking the formation of tubercles.
• The tubercle comprises an organized aggregation of enlarged macrophages that, because they resemble epithelial cells, are referred to as epithelioid cells.
• A peripheral collar of fibroblasts, macrophages, and lymphocytes surrounds the granuloma.
• Frequently the central region of epithelioid cells undergoes a characteristic caseous necrosis to produce a “soft” tubercle, the most characteristic hallmark of tuberculosis.
• When the antigen load at the initial infection site and regional lymph node is large, caseation necrosis may develop and lesions may later calcify.
• These calcified lesions of the primary site are referred to as the Ghon complex.
• After the development of hypersensitivity, the infection becomes quiescent and asymptomatic in the majority of patients (about 90%).
• In some, however, especially the very young and adults who are immunocompromised or who have other predisposing illnesses, the primary infection may evolve into clinical disease.
• The progression may be local at the site of the primary lesion, or it may be at one or more distant sites where bacilli have arrived during the early hematogenous spread.
• In a small number of persons whose initial tuberculous infection subsidies, secondary disease occurs in spite of acquired cellular immunity.
• In this phase of the disease, lesions are usually localized in the apices of the lungs (remember that tubercle bacilli require oxygen for growth).
• In about 5% of patients, apical pulmonary tuberculosis manifests itself within 2 years of the primary infection.
• Because of the acquired cellular immunity, bacilli are more promptly phagocytized and destroyed by the activated macrophages.
• As a result, in secondary tuberculosis, lesions remain localized and dissemination of organisms via the lymphatic vessels is usually prevented.
• Hypersensitivity promotes a more rapid caseation and fibrotic walling-off of the focus.
• Histologically the reaction is characteristic of tubercle formation, manifested by a local accumulation of lymphocytes and macrophages.
• T lymphocytes and their chemotactic lymphokines play a major role in the development of tuberculous granuloma.

These differences between primary infection and post-primary or reactivation are attributed to (1) resistance and (2) hypersensitivity induced by the first infection of the host with tubercle bacilli.

Ans. B: Primary complex

The bacilli is engulfed by alveolar macrophages multiply and give rise to a subpleural focus of tuberculous pneumonia, commonly located in the lower lobe or the lower part of the upper lobe.This is known as Ghon focus.

The Ghon focus together with the enlarged hilar lymph node constitutes the primary complex.

Small metastatic foci containing low numbers of MTB may also calcify.

However, in many cases these foci will contain viable organisms.

These foci are referred to Simon foci.

The Simon foci are also visible upon chest X-ray and are often the site of disease reactivation.

Ans. B: Primary pulmonary tuberculosis

Cavitation is rare in primary TB

Radiological changes of secondary TB includes ill-defined opacification in one or both of the upper lobes, and as progression occurs, consolidation, collapse and cavitation develop to a varying degree

Cavitation in lungs can be seen in

• C- Carcinoma – Squamous is most common
• A- Autoimmune – Wegener’s granulomatosis, Rheumatoid nodules
• V- Vascular – Emboli (septic emboli or bland emboli)
• I- Infection – Lung abscess, Bacterial pneumonia, Fungal pneumonia, Tuberculosis (secondary), Pneumatocele
• T- Trauma – Pulmonary laceration
• Y- Young (congenital) – Congenital cystic adenomatoid malformation, Pulmonary sequestration, Bronchogenic cyst

Ans. Tuberculosis

Ans. Tuberculosis

Ans. is ‘b’ i.e., A pateint who returns sputum postive which was curved by previous treatment

Some definitions of tuberculosis cases and treatment

• Case of tuberculosis : A patient in whom tuberculosis has been confirmed by bacteriology or diagnosed by a clinician.
• Sputum smear examination – Laboratory technique to screen sputum for tuberculosis, where acid fast bacilli (AFB) are stained red by the Ziehl Neelsen method, and then identified and counted.
• using microscopy.
• Smear positive tuberculosis – At least one initial sputum smears positive for AFB or one AFB positive.
• Smear negative tuberculosis – At least two negative smears, but tuberculosis suggestive symptoms and X-ray abnormalities or positive culture.
• Adherence – Person takes appropriate drug regimen for required time (also known as compliance).
• New case – A patient with sputum positive pulmonary tuberculosis who has never had treatment for tuberculosis or has taken anti – tuberculosis drugs for less than 4 weeks.
• Relapse – A patient who returns smear positive having previously been treated for tuberculosis and declared cured after the completion of his treatment.
• Failure case – A patient who was initially smear positive, who began treatment and who remained or became mear positive again at five months or later during the course of treatment.
• Return after default – A patient who returns sputum smear positive, after having left treatment for at least two months.
• Transfer in – A patient recorded in another administrative area register and transferred into another area to continue treatment (treatment results should be reported to the district where the patient was initially registered). Transfer out – A patient who has been transferred to another area register and treatment results are not known. Cured – Initially smear positive patient who completed treatment and had negative smear result on at least two occasions (one at treatment completion).
• Treatment completed – Initially smear negative patient who received full course of treatment, or smear positive who completed treatment, with negative smear at the end of initial phase, but no or only one negative smear during continuation and none at treatment end.
• Cohort – A group of patients in whom TB has been diagnosed, and who were registered for treatment during a specified time period (e.g. the cohort of new smear-positive cases registered in the calender year 2003). This group forms the denominator for calculating treatment outcomes. The sum of the treatment outcomes, plus any case for which no outcome is recorded (eg. still on treatment) should equal the number of cases registered.
• Case detection rate : – The case detection rate is calculated as the number of notification of new and relapse cases in a year divided by the estimated incidence of such cases in the same year.