Tuberculoid morphology in borderline lepromatous leprosy

Abstract

The morphologic spectrum of skin lesions in leprosy is characterized by cohesive epithelioid cell granulomas at the tuberculoid pole and by diffuse, macrophage granulomas at the lepromatous pole. Epithelioid cell granulomas indicate strong host resistance; therefore, a search for infective organisms in aspirates with epithelioid cell granulomas is likely to be disappointing. Conversely, macrophage granulomas are associated with poor host immunity to infective organisms1; appropriate stains demonstrate large numbers of infecting organisms. In short, in skin lesions the morphology of the granuloma reflects the bacterial density. The widely accepted Ridley-Jopling (R-J) 5-group classification of leprosy reflects the immunologic status of the patient and allows accurate calibration of the disease. The basis of this classification is a combination of the clinical, bacteriologic, histopathologic and immunologic findings.2 Cytomorphology in fine-needle aspiration cytology can also be used to place the lesions on the R-J scale; in general, the cytomorphology shows a strong correlation between the cell type of the infiltrate and the bacterial index (BI).1 This positive correlation also serves as a self-check to the Ziehl-Neelsen (Z-N) or other acid-fast staining procedure that may be used in the laborator