Abstract
To the Editor:
Mucormycosis is an invasive fungal disease caused by Mucor with high mortality. 1 Humans are infected primarily via inhalation of fungal sporangia, occasionally via ingestion of contaminated food or skin wounds. 2 In immunocompromised patients, Mucor can bind to host endothelial cells, causing endothelial cell damage and hyphae-invading blood vessels, leading to thrombosis and tissue necrosis. Herein, we describe a case of avascular necrosis of the left lower extremity caused by Rhizopus oryzae infection.
A 17-year-old female was transferred to our hospital with a sprain of the left lower extremity for 18 days and skin necrosis on the front of the calf for 14 days. She had been found to have diabetes mellitus three years ago, but was not treated properly. Physical examination revealed limited movement of the left lower extremity, bruised skin in the middle and distal segments of the calf, gangrene of 15 × 5 cm in size, and pale skin on the left foot. The pulse of the femoral artery and popliteal artery of the left lower limb was palpable; the pulse of the dorsal foot artery, anterior tibial artery, and posterior tibial artery was not palpable. The skin on the lower part of the left calf was cold and lacked sensation. Arteriography of the left lower extremity showed disruption of blood flow distal to the anterior tibial artery, posterior tibial artery, and peroneal artery. The diagnosis of avascular necrosis of the left lower extremity was established.
The patient underwent an amputation of left calf. Two days after surgery, histopathologic findings revealed fungal infection, which was considered Mucor infection (Fig. 1). Rhizopus oryzae was identified by fungal culture. The patient received anti-fungal treatment, amphotericin B (25 mg/d for 4 weeks) during hospitalization, and posaconazole (400 mg every 12 hours for 8 weeks) after discharge. At the last follow-up, she had recovered well. Currently, she regularly uses insulin to control blood sugar and actively participates in rehabilitation training.
Histopathologic examination showed Mucor (hexamine silver staining ×200).
Mucormycosis, although relatively rare, poses a serious threat to immunocompromised patients because of its persistently high case-fatality rate. Moreover, the clinical manifestations and signs of mucormycosis are non-specific, which makes the diagnosis and treatment of mucormycosis difficult. Direct culture and histopathology are the gold standard for the diagnosis of mucormycosis, which can help clinicians diagnose disease earlier and initiate treatment more quickly. The treatment of mucormycosis requires multidisciplinary collaborative intervention; timely and effective antifungal treatment can reduce mortality.