Lichtheimia

Lichtheimia is a genus of fungi in the order Mucorales. It was long treated as part of Absidia, and several species previously classified there are now placed in Lichtheimia, with Lichtheimia corymbifera being the most commonly implicated species in human disease. The genus also includes Lichtheimia ramosa and other related species.

These fungi are saprobic, found worldwide in soil, decaying vegetation, and dust. They can grow rapidly at warm temperatures and are capable of causing opportunistic infections in humans and animals, particularly under conditions of immune compromise.

Morphology and identification rely on the appearance of broad, mostly non-septate hyphae in tissue and characteristic aerial structures in culture. In tissue, the hyphae are typically wide and irregular, with frequent branching. Culture and molecular methods help distinguish Lichtheimia species, which is important for epidemiology and management.

Clinical significance is centered on mucormycosis, a rapidly progressive infection that can affect the rhino-orbital, pulmonary, cutaneous, or disseminated sites. Risk factors include diabetes mellitus, neutropenia, hematologic malignancies, solid organ transplantation, corticosteroid or iron overload states, and other forms of immunosuppression. The infection carries a high mortality rate, especially when diagnosis or treatment is delayed.

Diagnosis and treatment require a combination of prompt histopathology and culture, with molecular assays used for species confirmation. Management involves urgent surgical debridement when feasible and antifungal therapy, typically liposomal amphotericin B as first line, with possible step-down to posaconazole or isavuconazole depending on clinical factors and susceptibility. Addressing underlying risk factors is essential for outcome.