Figure 4 and 5: Histopathological pictures showing poorly formed
granulomas consisting of epitheloid cells
DISCUSSION
Cutaneous Tuberculosis (TB) is a relatively uncommon manifestation of
extrapulmonary TB (EPTB) accounting for 1-1.5 % of total cases of
EPTB.3Cutaneous Tuberculosis is caused by Mycobacterium tuberculosis(MTB) and
less commonly by mycobacterium Bovis or Bacillus Calmette-Guerin
vaccine.1
Three modes of dissemination of cutaneous TB have been described to date
which include primary inoculation, hematogenous spread and contiguous
spread.4Modes of primary inoculation include acupuncture, needle stick injury,
and insulin injection.1,5
Hematogenous spread of Cutaneous TB is also known in cases of AIDS and
chronic kidney
diseases.6
Depending on the bacterial load cutaneous TB has been classified as
either paucibacillary or multibacillary. Multibacillary forms of
cutaneous TB are tuberculous chancre, scrofuloderma, orificial
tuberculosis, acute miliary tuberculosis, and metastatic abscess often
called tuberculous
gumma.1Paucibacillary forms of TB are tuberculosis verrucosa cutis, lupus
vulgaris, and
tuberculids.1
Tuberculids usually develop as a host hypersensitivity reaction against
MTB infection in a visceral organ or distant skin
lesion.1,3Tuberculids include papulonecrotic tuberculid, lichen scrofulosorum,
erythema induratum of Bazin and nodular
tuberculid.1,3
The manifestation of cutaneous miliary TB is not specific.1,
2 Cutaneous manifestation
of miliary TB includes erythema, erythematous whitish papules later
developing into small vesicles which soon break down to form
umbilication and crust formation, and symptoms such as fever, weight
loss, and malaise can also be associated .1
Evaluation of Cutaneous TB needs proper history and examination along
with relevant laboratory investigations. The investigation includes
tuberculin skin test Serum QuantiFERON-TB Gold (QFT-G) levels, PCR, and
skin
biopsy.7,
8
Other tests include sputum culture and chest x-ray for identification of
pulmonary TB and miliary pattern of the
disease.7
Our case was diagnosed as cutaneous TB from a skin biopsy with Gene
Xpert test.
Since cutaneous tuberculosis almost invariably has a systemic
infestation, it is treated in the same manner as a systemic
TB.9Multidrug therapy with isoniazid, rifampicin, pyrazinamide, and
ethambutol are commonly used
drugs.7,
9 The treatment consists of
2 phases, initially intensive phase treatment for 2 months targets at
suppressing the bacterial load and a prolonged continuation phase for 4
months emphasizes on the complete elimination of the causative
organism.7,
9
Cutaneous TB can be prevented by the BCG vaccine and especially
BCG-vaccinated ones have less chance of dissemination forms of TB10