Lecture Notes: Tuberculosis Lymphadenitis

Overview of Tuberculosis (TB)

TB is a bacterial infection, primarily caused by:
- Mycobacterium tuberculosis (main cause)
- Mycobacterium bovis and some atypical mycobacteria (less common)
Transmission:
- Spread through droplet infection from coughs and sneezes of infected individuals

Pulmonary Tuberculosis: Affects the lungs
Extra Pulmonary Tuberculosis: Affects other parts of the body (15-20% of active cases)
- Tuberculosis Lymphadenitis: Most common form of extra pulmonary TB (20-40%)

Common Sites of Infection:
- Cervical Lymph Nodes: Especially the upper deep cervical lymph nodes
- Axillary, Mesenteric, and Inguinal Lymph Nodes

Cervical Lymph Nodes:
- Bacilli enter via tonsillar crypts of the palatine tonsil
- Affects jugular digastric lymph node and posterior triangle nodes
- In 20% of cases, involvement of adenoids affects posterior triangle nodes
Supraclavicular Lymph Nodes:
- Infection spreads from the apex of the lungs, penetrating the suprapleural membrane

Adenopathy:
- Non-tender, firm, discrete, mobile lymph nodes
- Histology: Non-specific reactive hyperplasia
Matting Formation:
- Large, firm swellings fixed to surrounding tissues
- Capsule involvement causes "matting"
- Pathognomonic of TB
Cold Abscess Formation:
- Caused by caseating necrosis
- No local rise of temperature, no tenderness, no redness
- Soft, fluctuant swelling
Collar-stud Abscess:
- Abscess pierces deep fascia, forming swelling under skin
- Two collections of pus communicate through narrow opening
Sinus Formation:
- Pus erupts through skin forming a persistent discharging sinus
- May cause surrounding skin ulceration
- Multiple sinuses with blue discoloration and undermined edges

Stages: Non-tender swelling → Matting → Caseating necrosis → Cold abscess → Collar-stud abscess → Sinus
Clinical identification of stages is crucial

Thank you for attending the lecture! Stay tuned for more insights in upcoming sessions. Have a great day!