The reversed halo sign as the initial radiographic sign of pulmonary zygomycosis

Zygomycosis is an emerging fungal infection that is associated with high mortality in hematological patients and stem cell transplantation (SCT) recipients. Radiology computed tomography (CT) imaging in particular facilitates the detection of lung involvement at an early stage of the infection. The reversed halo sign (RHS) has previously been reported in cryptogenetic organizing pneumonia and, more recently, as a manifestation of pulmonary zygomycosis. Here we describe a case of histologically proven zygomycosis due to Rhizopus microsporus in a SCT recipient. A chest CT scan performed on day +6 due to persistent fever unresponsive to antibiotics revealed the presence of the RHS, i.e., a focal ground-glass opacity mass surrounded by a solid ring of consolidation. The patient was treated with a combination of liposomal amphotericin B, caspofungin, and deferasirox, but subsequently developed a large pneumothorax and died on day +49 due to progressive infection. This case supports earlier observations that RHS may be an early radiological sign of zygomycosis, facilitating an aggressive diagnostic strategy.