Histoid leprosy: a rare exuberant case.

Leprosy is a neglected disease. We point up the need of recognizing the unusual clinical presentations of the disease in order to make early diagnosis and proper treatment possible, and break the transmission chain. The authors report a rare type of multibacillary leprosy: histoid leprosy and present images of numerous well-circumscribed indurated papules and nodules distributed throughout the entire body.

Histoid leprosy, an uncommon form of multibacillary leprosy, was first described by Wade in 1963.[1] Clinically, it is characterized by the presence of numerous indurated, infiltrated, keloid, skin-colored or erythematous papules and nodules with no preferred location (Figures 1,2 and 3).[2,3,4] Skin histology reveals an abundant amount of bacilli and elongated or fusiform histiocytes, similar to neurofibroma.[3,5,6] This form is rare in treatment-naïve patients. The literature discusses causal factors, such as drug resistance to dapsone or mutation of strains of Mycobacterium leprae..[2,7] The differential diagnosis should be made with sarcoidosis, dermatofibroma, cutaneous metastasis and angiosarcoma.[8]

Figure 1

Presence of keloid papules and nodules on the face

Figure 2

Papular-nodular erythematous lesions and some crusts on the back and upper limb

Figure 3

Presence of several papular-nodular, ulcerated, crusted lesions on the left forearm and left hand

We report the case of a 23-year-old male patient who lived in an endemic area of Rio de Janeiro and had an "18-month history of numerous nodules throughout the body." He denied leprosy. Serologies for HIV, syphilis and hepatitis B and C were negative. Skin smear showed a bacteriological index of 5.75. Mitsuda test was negative. No changes in sensitivity were seen. The patient had no disability degree. Wade staining showed multiple acid-alcohol fast bacilli with bacteriological index of 6+, histopathologically classified as histoid leprosy. The patient started multidrug therapy for multibacillary leprosy (Figures 4).

Figure 4

Microphotograph of the biopsy of the lesion showing hypercellular areas with rounded and fusiform macrophages arranged in stripes; large vacuoles are observed in between; HE, 200x. Insert: Intact bacilli, bacteriological index of 6+ (LIB = 5.95); Wade’s method, 1000x

Furthermore, it is important that health professionals recognize atypical leprosy presentations in order to perform appropriate treatment. Late diagnosis of a bacilliferous patient may occur and favors the transmission chain.[9]