Tuberculosis miliare of the right lung - Erler Zimmer 3D anatomy Series MP2060

This dissection model highlighting a Right Lung Milvian Tuberculosis is part of the exclusive Monash 3D anatomy series, a comprehensive series of human dissections reproduced with ultra-high resolution color 3D printing.

Clinical History.

A 74-year-old man presented with increasing shortness of breath and hemoptysis. Further history reveals a weight loss of 20 kg in 6 months, night sweats and chronic cough. He recently moved from a country where tuberculosis is endemic. On examination, he has hypoxic and tachypnea and has bilateral crepitations in all of his lung fields and an opaque left lung base on percussion. Her blood test with quantiferon gold is positive. Chest radiograph showed small bilateral nodular deposits and left basal pneumonia. He died of respiratory failure soon after admission.

Pathology

The right lung was sliced longitudinally and mounted to visualize the cut surface. The bronchi and bronchioles are slightly ectasic. Scattered throughout the lung parenchyma are a large number of small pale yellow nodules less than 1 mm in diameter. Similar small subpleural nodules are visible on the surface of the visceral pleura. The nodules are tubercles. This is miliary tuberculosis, so called because of the nodules' resemblance to millet seeds.

Further information

Tuberculosis (TB) is a chronic pulmonary and systemic infectious disease caused by Mycobacterium tuberculosis. Transmission most commonly occurs through inhalation of aerosolized droplets of this pathogenic bacterium, first described by Robert Koch (1882). Risk factors for contracting tuberculosis include being a resident of a developing country where the disease is endemic, immunosuppression (e.g., HIV, steroid use, anti-TNF use, and diabetes), chronic lung disease (e.g., silicosis), alcoholism, and malnutrition.
After initial lung infection with M. tuberculosis, the clinical manifestation varies. In 90% of individuals with an intact immune system enter a phase of asymptomatic latent infection. This latent tuberculosis can reactivate at any time in the patient's life. In the remaining 10% of patients, especially in the immunocompromised, they develop primary disease, which is immediate active TB infection. Manifestations of primary TB include symptoms of pulmonary infection (e.g., consolidation, effusion, and hilar adenopathy) and extrapulmonary symptoms including lymphadenopathy, meningitis, and disseminated miliary tuberculosis.
Secondary tuberculosis occurs when there is reactivation of a previous latent TB infection. About 10 percent of latent TB is usually reactivated during periods of weakened host immunity. Typical symptoms of reactivation are cough, hemoptysis, fever, night sweats, and weight loss.
Tuberculosis miliare occurs when the mycobacterium erodes into a pulmonary vein and seeds elsewhere. The organism may return to the lung and spread to the lung parenchyma as in this case. Systemic miliary tuberculosis can occur when mycobacterium is spread through the arterial system. Tuberculosis can then be deposited in any organ but most commonly in the liver, bone marrow, spleen, and adrenal glands.

The immune response against tuberculosis is mediated by TH1 cells that stimulate alveolar macrophages to attack mycobacteria. These macrophages surround the infection by forming a granuloma surrounding a central area of "caseous" (white cheese-like) necrosis. Secondary pulmonary tuberculosis can heal with fibrosis or progress as in this case. Progressive pulmonary tuberculosis sees erosion and expansion of the infectious lesion into the adjacent lung parenchyma. This leads to evacuation of the caseous center leading to fibrous cavitation. Erosion of blood vessels can cause hemoptysis. After tuberculosis treatment, the tissue heals by fibrosis but does not recover lung architecture.
The diagnosis of tuberculosis is usually made with a clinical history, chest X-ray, and multiple sputum cultures. Mantoux skin tuberculin test and serum interferon gamma release test can also be used to help screen for infection. Biopsies can be taken from the site of suspected infection for culture to aid in diagnosis. Treatment involves prolonged courses of multiple antibiotics, which depend on the antibiotic resistance of the infecting mycobacterium.

What advantages does the Monash University anatomical dissection collection offer over plastic models or plastinated human specimens?

• Each body replica has been carefully created from selected patient X-ray data or human cadaver specimens selected by a highly trained team of anatomists at the Monash University Center for Human Anatomy Education to illustrate a range of clinically important areas of anatomy with a quality and fidelity that cannot be achieved with conventional anatomical models-this is real anatomy, not stylized anatomy.
• Each body replica has been rigorously checked by a team of highly trained anatomists at the Center for Human Anatomy Education, Monash University, to ensure the anatomical accuracy of the final product.
• The body replicas are not real human tissue and therefore not subject to any barriers of transportation, import, or use in educational facilities that do not hold an anatomy license. The Monash 3D Anatomy dissection series avoids these and other ethical issues that are raised when dealing with plastinated human remains.