Case 111. Lepra neuritis (35 y-o M)
Biopsy from the thickened ulnar nerve of an Vietnamese male
Key words : Mycobacterium leprae, peripheral neuritis
Among the distorted nerve fascicles, dense infiltration of lymphocytes and epithelioid cells is observed (HE, low power).   Schwann cells in the nerve fascicles are identified by immunostaining for S-100 protein, confirming the diagnosis of chronic granulomatous neuritis in leprosy.
Non-caseating epithelioid granuloma with lymphocytic reaction is evident. Negativity of acid-fast staining is consistent with tuberculoid leprosy.   Reference case 111A
Thickened peripheral nerve in the neck of a 74 y-o male farmer, a resident of Kanagawa prefecture (gross findings). Peripheral nerve involvement (thickening) is characteristic of tuberculoid leprosy. Presentation of numbness is also a clue for the clinical diagnosis.