Leprosy Mailing List, August 1st,
2008
Ref.: Diagnosis of
leprosy
From: Das P. K., Amsterdam, The Netherlands
Dear Salvatore,
I refer to Dr.
Khalid’s message: “Mnemonics in leprosy”, LML, June 15th,
2008. I am not sure what
he really means with “Mnemonics in leprosy” but, I thank him for
introducing the important subject of diagnosis of leprosy and its
cardinal signs. I wish to
add a few comments.
Together with the first Cardinal Signs of
Leprosy (better defined by loss of sensation and hypopigmentation), it
is also useful to mention "hypopigmentation and depigmentation".
Complete loss of pigment
(depigmentation) is not common in leprosy. Depigmentation is seen in
vitiligo and, in my experience in
India
the depigmented patches of vitiligo are sometimes mistaken for
leprosy.
In cases of tuberculoid (TT) leprosy and often
in of borderline tuberculoid (BT) leprosy, identification of M.
leprae by slit-skin smear examination is negative, therefore, the
pathology of the biopsy at the margin of the active lesion is an
important diagnostic tool.
Also, if possible, simple immunohistology is helpful. Immunohistology is performed
using monoclonal antibodies to M. leprae PGL-1 and Lam (Ref.1). Positivity (even
minor) will indicate TT leprosy.
Further, where possible, antibody titre to gel
purified mycobacterial (not necessarily, M. leprae) 65KD
antigen, using 1/400 diluted sera should be carried out and reading of
OD value >.50 and can confirm the diagnosis of TT
leprosy too (Ref. 2-4).
Hope this information is useful to you.
P. K. Das
Ref. 1. Amer.J.Pathol.(1999), vol . 154, p 1793-18040
Ref. 2. j.clin microbial(1990):`vol 28; p 379-382;
Ref. 3. Acta Leprologica (1989) vol 7(suppl.1)p
117-120;
Ref. 4. USA Patent No: US6,416,962 B1 Jul9,2002.
