Histoid leprosy is a subtype of multibacillary leprosy characterized by well-demarcated papulo-nodular skin lesions over normal skin. It results from long-term dapsone monotherapy leading to drug resistance in Mycobacterium leprae. Histopathology shows expansive well-circumscribed granulomas in the dermis containing numerous intact bacilli. Treatment involves multidrug therapy for multibacillary leprosy.

1. HISTOID LEPROSY

2. HISTORY
Coined by Wade in 1960
Gk: ‘Histo’ – Tissue ; ‘Eioid’ – Resemblance
Wade documented MB cases on Dapsone / De
Novo
Immunological Profiling by Sehgal et al

3. INTRODUCTION
First described as a subtype of LL
Pts on long-standing DAPSONE Monotherapy
Initial Improvement  Relapse
Drug Resistance / Inadequate treatment /
Mutant Organisms

4. DEFINITION
Histoid Leprosy is an expression of MB
Leprosy, characterized by welldemarcated, Papulo-Nodular cutaneous and
subcutaneous lesions over apparently normal
skin, with infrequent Reactional episodes.

5. EPIDEMIOLOGY
Age distribution : 10 – 84 Y (commonly 20-39
Y)
Incidence :
3.2% Sehgal & Srivastava
2.8% Kalla et al
Male : Female – 5.7 : 1 ; 20% had ENL
Kaur, I., Dogra, S., De, D. and Saikia, U.N. (2009), Histoid leprosy: a retrospective study of 40 cases from
India. British Journal of Dermatology, 160: 305–310. doi: 10.1111/j.1365-2133.2008.08899

6. CLINICAL FEATURES
Disseminated,
03-50
in
number,
Papulonodular,
firm

soft,
erythematous

Copper
Coloured, hemispherical / dome-shaped /
umblicated, Shiny glistening lesions over
apparently normal underlying skin over
Face, Back, Buttocks and Limbs
Koebnerization ? Pseudo-isomorphic

7. CLINICAL FEATURES
CLASSIFICATION OF LESIONS :
Subcutaneous Nodules
Deeply fixed Cutaneous Nodules
Superficially placed Cutaneous Nodules
Soft Nodules
Plaques

8. SUBCUTANEOUS NODULE

aa

9. CUTANEOUS NODULES

n

10. KOEBNERIZATION

11. CUTANEOUS PLAQUES

12. CLINICAL FEATURES
FACIES:
- Old wrinkled atrophic skin with absent
eyebrows
- Normal facies without any manifestation of
leprosy
Eyebrows and nasal mucosa (cartilage) are
spared in most cases

13. DIFFERENTIAL DIAGNOSES
Conventional Lepromatous nodules / LL
ENL
Von Recklinghausen’s disease / NF-1
Molluscum Contagiosum
Keloids
PKDL
Cutaneous Sarcoidosis
Dermofibroma
Cutaneous Tumours

14. DIAGNOSIS
HISTORY
Treatment history (Duration / Drugs /
Compliance)
CLINICAL FEATURES
Histoid Facies / Characteristic PapuloNodular cutaneous lesions over
apparently normal skin
INVESTIGATIONS
SSS
HPE
IMMUNOLOGY

15. INVESTIGATIONS
SSS
Abundant Uniform Solid-Stained Red long rods
with tapering ends
Bacilli / few Globi (lack of Globea, matrix
substance secreted by metabolism of bacilli)

16. 
a

17. INVESTIGATIONS
HPE
Epidermal Atrophy
Mild Acanthosis
Flattening of Rete Ridges
Dermal Histoid Lepromas – Expansive , well –
circumscribed granulomas, covered by
Pseudocapsule

18. HPE
Layers of cells in Granuloma
Innermost layer - Polygonal
Periphery - Spindle shaped histiocytes,
containing long AFB arranged in groups along
long axis – ‘HISTOID HABITUS’
Numerous Solid-stained bacilli, few Globi
Absence of ETS / Foam (ETS hampers Bacillus
metabolism and death)  preserved Bacilli in lepra
(Virchow) cells

20. TUBERCULOID CONTAMINATION
Subcutaneous Histoid Lepromas
Definite foci of epitheloid cells located within
lesion substance or encircling fibrous capsule
? Tuberculoid component of Earlier Borderline
phase

21. INVESTIGATIONS
IMMUNOPROFILE (Sehgal et al)
Lowered cell mediated immunity
Enhanced humoral immune response
(Raised IgG, IgA, IgM)
Diminished complements

22. TREATMENT

23. THANK YOU