Lucio's phenomenon is a necrotizing panvasculitis: mostly a medium-sized granulomatous arteritis

Area of Science:

• Dermatology
• Pathology
• Infectious Diseases

Background:

• Lucio's phenomenon (LPh) is a severe complication of diffuse lepromatous leprosy.
• The precise pathogenesis and vascular involvement in LPh remain unclear.
• Previous studies lacked detailed characterization of the affected vessels.

Purpose of the Study:

• To elucidate the type, size, site, and form of vascular damage in Lucio's phenomenon.
• To correlate histopathological findings with clinical manifestations of LPh.
• To clarify the pathogenesis of necrosis in LPh.

Main Methods:

• Retrospective clinical and histopathological study.
• Analysis of clinical information from patient records.
• Microscopic examination of H&E, Ziehl-Neelsen, and Fite-Faraco stained slides.
• Direct immunofluorescence performed on select cases.

Main Results:

• Twelve cases of diffuse lepromatous leprosy with LPh were analyzed.
• Affected vessels were predominantly medium-sized arteries in the deep dermis and hypodermis.
• Histopathology revealed granulomatous inflammation, macrophage infiltration with bacilli, and vessel wall destruction, leading to lumen narrowing/occlusion.
• Smaller vessels showed leukocytoclastic vasculitis.
• Occlusion of these vessels resulted in ischemic necrosis and epidermal detachment.

Conclusions:

• Lucio's phenomenon is a necrotizing panarteritis affecting medium-sized deep dermal vessels.
• The vascular damage explains the characteristic necrotic, purpuric, and ulcerative lesions.
• Understanding LPh vascular pathology clarifies its clinical presentation and pathogenesis.