Abstract

Leprosy, also known as Hansen’s disease, is a chronic infectious disease caused by Mycobacterium leprae and Mycobacterium lepromatosis. We present a long-standing case of widespread disease in order to highlight the clinical and histological features that should be considered in this relatively uncommon diagnosis. A 56-year-old female with a 3-year history of facial and distal extremity paresthesias underwent neurological evaluation without conclusion. Two months prior to biopsy, she developed a diffuse rash, thought to be urticarial, which was treated with prednisone unsuccessfully. She subsequently developed diffuse erythematous plaque-like lesions, worsening paresthesias, and inability to close her eyes. A punch biopsy revealed a superficial and deep granulomatous dermatitis with non-caseating granulomas tracking along vessels and nerves. Acid-fast stains revealed numerous bacilli within the granulomas. 16S ribosomal RNA sequencing confirmed the presence of Mycobacterium leprae. The patient was treated with immunomodulatory and anti-mycobacterial therapy and has seen marked clinical improvement since. However, her lower extremity paresthesias and lagophthalmos have not resolved. In long-standing cases such as this, neuropathies and disfiguring changes, such as madarosis and leonine facies, may persist. This case highlights the importance of timely diagnosis of this infectious disease, which can be difficult due to the variable clinical manifestations of disease, dependent on the host immune system. While leprosy is a less common cause of infection today (around 150 new cases reported in the United States each year), it is very much still present, is curable, and should remain on the clinical and histologic differential, even in cases without a notable travel history or high risk exposures.

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