1. Mycobacterial diseases Tuberculosis
Classification according to mode of infection:
1- exogenous inoculation:
A- tuberculous chancre
B- tuberculosis veruucosa cutis
2- endogenous by autoinoculation & direct spread:
A- scrofuloderma
B- tubeculosis cutis orificialis

2. Tuberculosis 3- haematogenous spread : A- Lupus vulagaris
B- miliary TB
4- Tuberculides:
A- Papulonecrotic tuberculides
B- Erythema induratum
C- Lichen scrofulosorum
3- haematogenous spread :

3. Diagnosis
Tuberculine testing: detects cell mediated immunity to TB, by Mantoux test; 5 TU of PPD is injected intradermally & results read hrs later, any induration of 10 mm or more indicates infection, biopsy with acid fast staining
PCR detecting the DNA of the organism
Culture is the golden standard determining antibiotic sensitivty & resopnse to treatment

4. LEPROSY
Caused by mycobacterium leprae Weak acid fast, never grown in vitro Target organs are nerves & skin Lives in temp. 30°C which is below core temp lesions are in cooler areas of body sparing central body & scalp male to female is 1.5:1 incubation period 5-20 years, that’s why patients are usually adults

5. CLINICAL FEATURES Types of leprosy
1- indeterminate leprosy: one or more hypopigmented macules, occur anywhere, nerve function & hair growth unimpaired 2- Tuberculoid leprosy (TT) 3- Lepromatous leprosy(LL) 4- Borderline leprosy: lesions are intermediate in no & asymmetrical with characteristic punched out appearance

6. BT BL Tuberculoid Borderline Lepromatous leprosy leprosy leprosy (TT) (BB) (BL) decreased immunity & increased organsism no.

7. Differences between polar types
Lepromatous
Tuberculoid
Clinical feature
Few
Single or few
skin lesion
Number
Any size
Size
Wide spread & symmetrical
Asymmetrical
Distribution
Not
Well demarcated
Margin
Elevated
Elevation
Smooth
Dry, scaly, absent hair
Surface
Late & mild
Early & marked
Sensory loss
Late
Early
Sweat loss

8. No of bacilli in skin lesions Lepromin test Histopathology
LEPROMATOUS
TUBERCULOID
CLINICAL FEATURE
&Late bilateral symmetrical
Early & near the lesion
Nerve involvement
Many
Scanty or absent
No of bacilli in skin lesions
Negative
Positive
Lepromin test
Foamy histeocytes
Epithelial cell granuloma
Histopathology
Progressive
Spontaneous healing
Natural course
Immune complex
Cell mediated
Lepra reactions
Common
Does not occur
Systemic involvement