Clinicohistological disparity in leprosy

Introduction

Leprosy has got a wide clinical spectrum which is manifested depending upon the immune status (CMI) of the host. The histology of different types of leprosy is fascinating and demonstrates wide variation too. Usually they corroborate each other but at times problem may arise. Here we present such a disparity between the clinical findings and histology in a case of leprosy (Hansen′s disease).

Case Report

An apparently healthy elderly man presented with a single anesthetic, raised, tender, erythematous lesion near the medial canthus of right eye of 3 years′ duration [Figure - 1]. The disease started insidiously with a papule, later on became a plaque. He received MDT (Dapsone, rifampicin and clofazimine) irregularly for 3 months without any obvious benefit. There was no history of contact of leprosy in the family or neighborhood and he denied any history of diabetes, tuberculosis or any other major illness. General physical examination was normal. Cutaneous examination revealed a round, erythematous, tender plaque with little scaling over the surface at the medical canthusof the right eye. It was unrespondent to pain and temperature stimuli. Right supraorbital nerve was thickened and tender on palpation.

Routine haemogram and skiagram of chest were normal. However, the slit skin smear showed AFB in both solid and fragmented form. Bacterial index was 2+. The clinical diagnosis was borderline tuberculoid (BT) leprosy with downgrading reversal (Typel or delayed hypersensitivity reaction. A 4mm punch biopsy was taken from the edge of the lesion and was stained by hematoxylin/eosin and Fife Faraco′s stain.

Histology revealed an atrophic epidermis with loss of rete ridges. The dermis was occupied by diffuse granulomatous infiltrate comprising predominantly of macrophages, foamy histiocytes and a few lymphocytes. No nerve bundles could be made out. Infiltration was also seen around the hair follicles and sweat glands. Grenz zone was free from any cellular infiltration. FF stain revealed plenty of acid-fast bacilli within the foamy histiocytes and macrophages. They were mostly solid, a few granular. At some places, the bacilli were arraged in globi. At one place of the granuloma, there was attempted giant cell formation; that too foreign body type. The histological findings were suggestive of borderline lepromatous (BL) leprosy.

Thereafter, lepromin test was carried out with Dharmendra antigen which showed very weakly positive reaction.

Discussion

Leprosy having a wide clinical spectrum, has been classified by several scientists in order to offer the best possible treatment and recognize the stages in a universal way. Only Madrid (International classification) and Indian Leprologists′ classification have been widely accepted and are being used in leprosy work.[6] An endeavor has been made by Ridley and Jopling[2] to abridge the several lacunae between these two classifications. However, due to build in pitfalls in the latter classification, it has not been accepted by all leprologists. Sehgal et al[3],[4] while working on these facers, showed that considerable variation does exist between the morphological diagnosis and histological impression which was again discussed in detail by Sehgal et al[6] and other workers.[5]

A system of classification has got immense value in leprosy because of the varied spectrum of its clinical manifestations. Accordingly, continuous efforts are being made to develop an adequate classification, which not only embraces the clinical features but also the histological, bacteriological and immunological facers. These objectives seemed to have been met in Ridley-Jopling classification[2] which, therefore, serves as an anchor for leprosy work in fields as well as institutions. Studies by Sehgal et al[6] have revealed the consistency among clinical, histological, bacteriological and immunological parameters in only 44% of cases. The rest 56% showed disparity in either one or another parameter. Meyer et al′ have found agreement in 77.2% of cases between clinical and histological diagnoses. Our case was another glariing example of such disparity. Clinically it appeared as BT leprosy with downgrading reversal reaction but histologically and immunologically proved to be a BL case.

Such discrepancies may arise in clinical practice. In these situations, one should consider the case a multi-bacillary one and opt for MDT with newer drugs such as sparfloxacin, ofloxacin and minocycline with daily administration of rifampicin, to prevent relapse and recurrence.