Histoid hansen in post elimination era: A seven-year clinicopathological study

Histoid Hansen (HH) has been thought to be a rare variant of multibacillary leprosy and is considered by some as a reservoir and important source of transmission of disease. This retrospective study, carried out at Guntur Medical College, Guntur (Andhra Pradesh) reports the incidence, clinical and histopathological features of HH diagnosed over last seven years (January 2011 to December 2017). A total of 102 leprosy cases were referred for histopathology during the study period. Of these 14 cases were HH (incidence- 13.5%). Fifty percent of cases (7/14) were de novo and biopsy was done with various differential diagnoses of cutaneous leishmaniasis, sarcoidosis, tuberculosis and fungal infection. The other seven cases were known cases of leprosy with irregular treatment history. One patient developed erythema nodosum leprosum. All cases showed classic histopathological features and high bacillary index. The HH cases were further subtyped into three histological variants namely, 1) Pure fusocellular, (PFC) when the dermal cell collections comprised entirely of fusiform or spindle cells; three out of 14 cases (21.4%) were categorized as PFC. 2) Fusocellular with Epithelioid component (FCE), when epithelioid cells are also seen in addition to spindle cells; two out of 14 cases (14.2%) were categorized as FCE. 3) Fusocellular with vacuolated cells (FCV), when vacuolated cells and spindle cells are seen; 9 out of 14 cases (64.2%) were categorized as FCV. It is apparent that the awareness of various histo-morphologies of this rare histoid form of Hansen is essential as it can also be confused with any histiocytic and spindle cell lesions with storiform patterns like fibrohistiocytoma, dermatofibroma, and neurofibromas. Fite Faraco staining will be useful in demonstrating lepra bacilli and will be relevant in arriving at correct diagnosis specially in situations when clinical/ histopathological suspicion is of conditions other than leprosy.