Leprosy Mailing List – May 23, 2013
Ref.: (LML) New Case Detection
From: Dr.HK Kar, New Delhi, India
Dear Dr. Schreuder,
I would like to refer to the LML letter of Maria Leide of May 22, 2013 and the nice visual presentation of Histamine Test.
The sympathetic nerves of the skin supplying the blood vessels are impaired before the sensory nerves are affected, hence very helpful for early diagnosis of leprosy. Histamine elicits two reactions in normal skin in which the sympathetic nervous system is intact:
- a flare, caused by dilatation of small blood vessels of the skin, and
- a weal, due to local injury to the skin. In the skin affected by leprosy.
The flare may be impaired or absent, due to malfunctioning of the sympathetic nervous system and only a weal is seen. The flare is delayed or feeble in indeterminate and borderline leprosy; and absent in a tuberculoid lesion.
This test is useful only to differentiate hypopigmented macules of leprosy from those of other skin diseases. There will be normal flare (positive test) in other hypopigmented macules due to non-leprosy conditions like vitiligo, pityriasis alba, fungal infections, etc. In dark patients this test may not be helpful because flare may not be easily visible.
Regards,
Dr (Prof.) H K Kar
Consultant in Dermatology and Leprosy
Director and Med. Superintendent
P.G.I.M.E.R. and Dr Ram Manohar Lohia Hospital
Baba Kharag Singh Marg
New Delhi-110001
LML - S Deepak, B Naafs, S Noto and P Schreuder
LML Archives: http://www.aifo.it/english/resources/online/lml-archives/index.htm
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