Histoid leprosy: a retrospective clinicopathological study from central Nepal

Histoid leprosy is a rare variant of lepromatous leprosy characterized by varied morphological and histopathological appearance while having a high bacillary load. These factors contribute to an ominous threat to the elimination status of leprosy, whereby these patients may act as a reservoir of infection.

To identify the clinicopathological characteristics of histoid leprosy in Chitwan, Nepal.

A retrospective hospital-based study spanning a period of 6 years was carried out at our department. All cases clinically and histopathologically suggestive of histoid leprosy were included in our study, and all relevant data were recorded and analyzed as per standard protocol.

Histoid leprosy comprised 2.9% of all leprosy cases. Mean age of 39.45 years and male:female ratio of 1.75:1 were seen. Previous history of leprosy was obtained in 72.7%, and de novo development of histoid leprosy took place in 27.3%. Papules were the most common lesion seen, and upper limbs were the most frequent site of involvement, and the ulnar nerve was enlarged in most cases. Mean bacillary index was 5.39. Histopathology showed epidermal atrophy, positive Fite-Faraco stain for lepra bacilli, spindle-shaped histiocytes arranged in various patterns, and a well-circumscribed area of cells in the dermis in all cases. Grenz zone and pseudocapsule were seen in the majority of patients. All cases responded well to multibacillary multidrug therapy (MB-MDT) of 2 years.

A high index of suspicion is essential for diagnosing histoid leprosy, both clinically and histopathologically.