Dear Editor,
Hansen’s disease is a chronic infectious granulomatous disease caused by Mycobacterium leprae. Histoid leprosy is an uncommon variant of multibacillary leprosy with unique clinical and histological characteristics. It occurs in lepromatous patients who relapse after dapsone monotherapy in the presence of dapsone resistance or rarely de novo.[1] We report a rare presentation of histoid leprosy in a 30-year-old male who presented with papules and plaques localized to the forehead region.
A 30-year-old male presented with asymptomatic skin-colored lesions on the right side of the forehead and bridge of the nose for 2 years. There was no history of insect bites or trauma. Family history was non-contributory.
On examination, multiple, discrete skin-colored to erythematous papules and plaques, with prominent follicular openings seen on the right side of the forehead and bridge of the nose with midline demarcation [Figure 1a]. The size of the lesions varied from 0.5 to 1.0 cm. The lesions were soft in consistency, compressible, and diascopy was positive. A dermoscopic examination revealed an orangish brown hue with follicular openings. General physical and systemic examinations were within normal limits. Routine investigations were unremarkable, and ELISA (Enzyme linked Immuno Sorbent Assay) for HIV was negative.
Figure 1.
(a) Multiple, discrete skin colored to erythematous papules and plaques on forehead and nose. (b) Hyperpigmentation on forehead and bridge of the nose
The differential diagnoses considered were sarcoidosis, xanthomas, and Kimuras disease. A skin biopsy taken from the lesion over the forehead showed mild orthokeratosis and thinned-out epidermis. Superficial and mid dermis shows aggregates of histiocytes, multinucleated giant cells, lymphocytes, and plasma cells [Figure 2a and b]. Fite Faraco staining for lepra bacilli revealed numerous uniformly stained bacilli arranged in clumps and globi with a bacterial index of 4 [Figure 3a].
Figure 2.
(a) Inflammatory cell collection in the dermis (H and E, 10x). (b) Entrapped adnexa in the sheet of histiocytes (H and E, 40x)
Figure 3.
(a) Fite Faraco staining for lepra showing numerous rod-shaped bacilli in the histiocytes (oil immersion). (b) Discrete and clumped long, slender, acid-fast bacilli (oil immersion)
Based on the clues from the skin biopsy, cutaneous and peripheral nerve examination were done which were unremarkable. Skin smears taken from the lesion over forehead, and ear-lobe showed discrete and clumped long, slender, acid-fast bacilli [Figure 3b]. A diagnosis of de-novo histoid leprosy was made, and the patient was started on multibacillary multidrug therapy. All the lesions were resolved with minimal hyperpigmentation in six months [Figure 1b], and the patient is now on regular follow-up.
Histoid leprosy (HL) is a rare variant of lepromatous leprosy, first described by Wade in 1960.[2] The condition has classically been mentioned in relation to relapse or resistant Hansen’s disease cases on either Dapsone monotherapy or incomplete/irregular multi-drug therapy, rarely de novo. The incidence of HL among leprosy patients in India is estimated to be 2.79% to 3.60%.[1] The average age at diagnosis is between 21 and 40 years, with a male preponderance.[1,2]
Histoid leprosy is clinically characterized by cutaneous or subcutaneous nodules or papules, which are usually painless, discrete, firm, smooth, globular, and skin-colored to yellowish brown, with normal appearing skin surrounding it.[1] However, in the present case, the lesions are soft in consistency, which could be attributed to softening secondary to a high bacterial load.[3] The lesions are typically located on the posterior and lateral aspects of the arms, buttocks, thighs, dorsum of the hands, the lower part of the back, and over the bony prominences, especially over elbows and knees, with the number of lesions varying from 3 to 50. Various uncommon presentations have been described, including xanthomatous, and umbilicated molluscum contagiosum-like lesions.[4]
The pattern of forehead lesions in the present case could be the result of the phenomenon of transepidermal elimination of lepra bacilli following trivial trauma, which gives rise to new leprosy lesions, as proposed by Namisato et al.[5]
Yellow-orange structures in combination with linear vessels in a branching pattern under dermoscopy suggest granulomatous skin condition[6] which was consistent with the findings of the present case.
Dermoscopy of histoid leprosy in a case report demonstrated whitish yellow structureless areas throughout, a peripheral rim of brownish pigmentation, and linear branching vessels running towards the center, which was in contrast to the findings of the present case.[7]
In slit skin smears, the bacilli were abundant, uniformly stained, longer, slender, and with tapering ends when compared to regular lepra bacilli.[1] Classical histopathologic findings of histoid nodules include epidermal atrophy, a traditional subepidermal grenz zone, and fusiform histiocytes arranged in whorled, criss-cross, or storiform patterns. The histopathology of the present case is consistent with these findings.
Our case is unique in the sense that this localized variety of histoid leprosy, presenting as papules and plaques without any history of anti-leprosy treatment is extremely rare. The high bacillary load in the histoid variety of leprosy is a potential reservoir of the infection, making it essential to watch for new cases and provide complete treatment to achieve our goal of the elimination of leprosy.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
- 1.Batra N, Hatwal D, Dandona S. Histiod leprosy-how is it different from lepromatous leprosy?A case report. J Med Sci Clin Res. 2014;2:555–8. [Google Scholar]
- 2.Sri KU, Kumar MA, Reddy CV, Sagar PV. Denovo histoid Hansen's disease-“Bolt from the Blue”. Journal of Basic and Clinical Research. 2018;5:18–22. [Google Scholar]
- 3.Rao AG, Kolli A, Farheen SS, Reddy UD, Karanam A, Jagadevapuram K, et al. Histoid leprosy presenting with figurate lesions: A unique and rare presentation. Indian J Dermatol Venereol Leprol. 2018;84:736–9. doi: 10.4103/ijdvl.IJDVL_475_17. [DOI] [PubMed] [Google Scholar]
- 4.Pathania V, Oberoi B, Baveja S, Shelly D, Venugopal R, Shankar P. A dissimulate presentation of histoid Hansen's disease in the form of erythema nodosum leprosum. Int J Mycobacteriol. 2019;8:208–10. doi: 10.4103/ijmy.ijmy_43_19. [DOI] [PubMed] [Google Scholar]
- 5.Namisato M, Kakuta M, Kawatsu K, Obara A, Izumi S, Ogawa H, et al. Transepidermal elimination of lepromatous granuloma: A mechanism for mass transport of viable bacilli. Lepr Rev. 1997;68:167–72. doi: 10.5935/0305-7518.19970023. [DOI] [PubMed] [Google Scholar]
- 6.Lallas A, Zalaudek I, Argenziano G, Longo C, Moscarella E, Di Lernia V, et al. Dermoscopy in general dermatology. Dermatol Clin. 2013;13:679–94. doi: 10.1016/j.det.2013.06.008. [DOI] [PubMed] [Google Scholar]
- 7.Ankad BS, Sakhare PS. Dermoscopy of histoid leprosy: A case report. Dermatol Pract Concept. 2017;7:63–5. doi: 10.5826/dpc.0702a14. [DOI] [PMC free article] [PubMed] [Google Scholar]