Histoid leprosy - A rare clinical presentation

Abstract

Histoid leprosy is considered a rare form of lepromatous leprosy. Its peculiar clinical picture makes its diagnosis a challenging one, which can delay starting treatment and perpetuate the disease as endemic. In addition to representing a reservoir of bacilli, and being an important means of contamination, these patients have greater resistance to standard treatment. This is a report of a typical case of this rare presentation, aiming to share the knowledge and favor earlier diagnosis of the disease.

Firm nodular plaque over the foot

“…This disease has an unusual clinical picture, which can put a hold on a correct diagnosis, resulting in a delay in starting treatment and perpetuating the disease as an endemic. [ 3 ] Besides the usual clinical appearance as soft to firm skin-colored papules/nodules, HL has reported in different forms resembling the keloid, molluscum contagiosum, neurofibroma, dermatofibroma, cutaneous leishmaniasis, deep mycosis, xanthoma, cutaneous metastasis, or reticulohistiocytosis. [ 3 4 ] A whorl pattern of spindled histiocytes found on histopathology can mimic dermatofibroma/neurofibroma.…”

“…[ 3 ] Besides the usual clinical appearance as soft to firm skin-colored papules/nodules, HL has reported in different forms resembling the keloid, molluscum contagiosum, neurofibroma, dermatofibroma, cutaneous leishmaniasis, deep mycosis, xanthoma, cutaneous metastasis, or reticulohistiocytosis. [ 3 4 ] A whorl pattern of spindled histiocytes found on histopathology can mimic dermatofibroma/neurofibroma. [ 2 4 ] Fite-Faraco staining of tissue samples is an important and sensitive method for displaying Mycobacterium leprae in the form of pinkish slender red rod like structures arranged in clumps while the background stain is blue [ Figure 3 ].…”

“…Since HL represents a huge reservoir of live bacilli and is an important source for transmission of leprosy, they need early detection and complete treatment. [ 3 ] A variety of regimens, including rifampicin, dapsone, clofazimine, minocycline, and ofloxacin, had been tried, however, the standard WHO MB-MDT is considered the most effective, unless drug resistance study from skin lesional tissue shows any resistant strain to any MDT drug/s[ 5 ]. In present case, biopsy material was not sent for drug-resistant study as the patient was treatment naive.…”

Leprosy Classification, Clinical Features, Epidemiology, and Host Immunological Responses: Failure of Eradication in 2023

“…Histoid leprosy: It is an atypical variant of LL with distinctive histopathological and clinical features [ 68 ]. It commonly occurs due to dapsone monotherapy or irregular treatment, or sometimes de novo.…”