Histoid leprosy with ENL reaction

Introduction

Histoid leprosy is characterised by the presence of nodules which are firm to hard in consistency and are sharply delimited from the surrounding skin. [1] In rare instances, histoid leprosy may undergo ENL reaction which is manifested histologically, as collection of histiocytes, neutrophils, lymphocytes and oedema in the dermis.

Case Report

A 23-year old man presented with skin-coloured shiny nodules on both pinnae of the ear for the last 18 months. After 6 months, he developed multiple, discrete, firm to hard nodules on extremities. Some of these nodules were mildly painful. After another 2-3 months, he noticed softening of the nodules on legs and feet followed by ulceration with purulent discharge. There was no history of any other painful eruptions or constitutional symptoms. In the past, he had visceral leishmaniasis for which he was treated adequately with sodium antimony stibogluconate.

On cutaneous examination, skin was ery-thematous with diffuse infiltration over face, extensor aspects of upper and lower limbs and lower part of back. There were multiple, discrete, cutaneous and subcutaneous, skin-coloured, shiny papules over both pinnae and firm nodules on both upper and lower limbs distributed bilaterally and symmetrically. The size of nodules varied from 0. 5 to 1. 0 cm. The papules over forehead and bridge of the nose had sharply demarcated edges. Some of the subcutaneous nodules present on the legs and feet had shallow ulcerations in the centre with serosanguinous discharge. There was no thickening and/or tenderness of peripheral nerves. Hair, nails and mucous membranes were normal.

The patient was started on multidrug therapy viz. daily dapsone 1 00mg, clofazimine 50 mg, monthly dosage of 600 mg rifampicin and 300 mg clofazimine when he started developing softening of few more subcutaneous nodules with pustulation and ulceration. Laboratory investigations like haemogram, blood glucose, liver and kidney function tests were normal. The culture from discharge was sterile. Slit-smear examination from lesions of ears and face were positive for AFB (BI-5) with 75% solid bacilli (Ziehl-Nielsen stain)and negative for LD bodies (Giemsa stain). Skin biopsy with a 4mm punch, from a firm nodule on foot showed tumorous collections of spindle-shaped cells arranged in a criss-cross fashion, collection of histiocytes, neutrophils, lymphocytes and oedema in the dermis alongwith infiltration of the vessel wall by neutrophils and deposition of fibrinoid material.

Discussion

ENL reaction has rarely been documented in histoid leprosy. Wade[2],[3] in 1963 found cutaneous and subcutaneous histoid nodules in lepromatous leprosy cases. These nodules may occasionally manifest central softening. These cases did not undergo ENL type of reaction. However, Ramanujam and Ramu have reported that in histoid lepromatous cases there was a tendency for softening to occur in the centre of the nodule and in some instances this was a prelude to the occurrence of pustulating and ulcerating type of reaction. These complications took the form of acute exacerbation of the existing lesions, classical lepra reaction, lepra reaction with pustulation in lesions, ulceration of nodules with or without the constitutional symptoms or ENL alone. Bhutani in 1974 found classical ENL reaction in three of his twenty patients of histoid leprosy which occurred during sulphone therapy.

In our case, mainly the subcutaneous nodules showed softening, ulceration and discharge more so after initiation of MDT, without any other feature of type 2 reaction. Skin biopsy from these lesions confirmed ENL reaction. The features of our case were similar to the cases reported by Ramanujam and Ramu. [3] The occurrence of reaction (classical ENL or the mild type 2 reaction) is reiterated since the common perception is that reactions are not seen in histoid leprosy.