Evolution of histoid leprosy (de novo) in lepromatous (multibacillary) leprosy

Abstract

A 26‐year‐old man presented with persistent redness of the face over the past 2 years and thickening of the ears for a year. The current state was preceded by three to four episodes of epistaxis, 2–3 months previously. The patient had not received any treatment. Cutaneous examination revealed indurated (infiltrated) plaques on the face and ears over an apparently normal‐looking skin, and numerous, small, ill‐defined, slightly hypopigmented, shiny macules all over the body. They were bilateral and symmetric (Fig. 1a,b). There was no variation in the cutaneous sensations of temperature, touch, and pain. The patient showed loss of the lateral eyebrows and conjunctival congestion. Examination of the nerves revealed enlargement of the ulnar, radial, posterior tibial, and right common peroneal nerves; however, there was no tenderness of the nerves. Systemic examination was within normal limits. Examination of a slit‐skin smear (under oil immersion), prepared from a representative lesion (plaque), demonstrated an abundance of solid and uniform‐staining acid‐fast bacilli, occurring either singly or in parallel clumps/globii, in an average field (6+). Furthermore, a scraping mount (10% KOH) prepared from the lesion on the back was negative.(a, b) Histoid leprosyimageHematoxylin and eosin‐stained sections prepared from a biopsy taken from a plaque revealed a conspicuous granuloma composed of peculiar spindle‐shaped histiocytes. Several of the granulomas were present in the mid and lower dermis. They were characterized by whorled, criss‐cross, or parallel patterns. Solid and uniform‐staining, slender, rod‐like (length three times that of the breadth) acid‐fast bacilli were found scattered throughout the section. A few histiocytes closely packed with acid‐fast bacilli, together with lymphocytic infiltrates, were also seen. There was a prominent eosinophilic stained clear zone just below the epidermis. It was free from acid‐fast bacilli as well as the inflammatory infiltrate (Fig. 2a,b). A definitive diagnosis of untreated lepromatous leprosy (LL) changing to histoid leprosy (de novo) was made.(a, b) Histoid leprosy depicting granuloma formed by histiocytes displaying whorl‐wind, criss‐cross or interlacing pattern, and a clear zone beneath the epidermis (H&E ×40) Solid and uniform staining acid fast bacilli, – slender, rod‐like, length 3 times that of breadth found scattered throughout the granuloma (H&E ×100)image