18. Sub-acute and chronic blood disseminated tuberculosis

Essay 18- Subacute and chronic blood disseminated tuberculosis

• What is it?
• Potentially fatal form of disseminated disease due to the hematogenous spread of tubercle bacilli to the lungs and other organs
• Results in the formation of millet seed-sized tuberculous foci
• Disseminated tuberculosis is defined as the simultaneous involvement of at least two non-contiguous organ sites of the body or infection of the blood, bone marrow, or liver
• Etiology
• Mycobacterium tuberculosis
• Non-spore forming, non-motile, obligate-aerobic, facultative, catalase-negative, intracellular bacteria
• Stained by Ziehl-Neelsen stain
• Histopathology
• Gross examination- small, punctate, gray to reddish-brown, rounded lesions of the more or less uniform size seen in the lungs and various other organs
• Microscopic- each focus represents a typical tubercle with caseous necrosis in the center having tubercle bacilli surrounded by typical Langhans type giant cells, epithelioid cells, lymphocytes, and fibrocytes
• Symptoms
• Acute miliary TB
• Seen under 40 years of age
• Evening rise of temperature and night sweats of 1-2 weeks duration
• Patient can have early morning fever spikes
• Dry cough with scanty sputum
• Dyspnea
• Hemoptysis (sometimes)
• Cryptic miliary TB (chronic)
• Occurs primarily in patients over 60 years of age
• General debility is the dominant clinical feature which mimicks metastatic carcinoma
• The patients have a normal chest radiograph and negative skin tuberculin test, causing a delay in diagnosis
• Fever
• Generalized weakness
• Weight loss
• Cough
• Physical exam
• Hepatomegaly
• Splenomegaly
• Lymphadenopathy
• Diagnosis
• Lab tests
• The most common hematological abnormality encountered in miliary TB is anemia of chronic disease.
• Elevated acute phase reactants in the form of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are frequently encountered
• CXR
• Shows typical miliary mottling
• i.e., homogenously distributed discrete uniform size (1 to 2 mm) millet-shaped lesions in all lung zones
• This is the hallmark for diagnosis of miliary TB

• TST
• Shows anergy in miliary TB (absence of normal immune repsonse)
• It can become positive during antituberculosis therapy
• Biopsy specimen
• Shows granulomatous inflammation with central caseation, with or without tubercle bacilli