The Significance of “Black Turbinate Sign” on MRI

Abstract

A 65-year-old diabetic man was referred to our hospital with left facial numbness, headache, and malaise approximately 2 weeks' duration. Initially, his blood glucose level and HbA 1c level were measured at 592 mg/dL and 12.6%, respectively. With strict control of blood sugar, antibiotic therapy was started because of suspected bacterial sinusitis on initial brain magnetic resonance imaging (MRI). His symptoms seemed to improve, but the facial pain and headache were suddenly aggravated at 2 weeks of admission. He was consulted to our department. Endoscopic examination revealed the black eschar in the inferior turbinate (Figure 1). Rechecked MRI showed total lack of enhancement (black turbinate sign) of the inferior turbinate of left side on T1-weighted image (Figure 2). Under general anesthesia, the patient underwent endoscopic surgery with wide excision of the necrotic tissue. Histopathologic examination demonstrated angioinvasive hyphae with characteristics of mucormycosis (Figure 3). After surgery, he finished a 6-week course of amphotericin and he remained symptomfree 18 months later. Mucormycosis is an acute opportunistic, angioinvasive, and devastating fungal infection which is associated with high mortality rates. 1 There has been a significant increase in incidence over the last 2 decades. 2 Early and accurate diagnosis of invasive mucormycosis remains a challenge for physicians. However, patients with invasive mucormycosis initially present with nonspecific symptoms and signs, leading to delays in diagnosis and imaging modalities and cultures are not usually useful for diagnosis. 2-4 Mucor organisms have the propensity of angioinvasive hyphae that results in

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“…Imaging plays an important role in making an early diagnosis. The reason attributed for this lack of enhancement is the angioinvasive nature of fungal hyphae which infiltrates the vessels supplying the mucosa 5,6,7 . In our study, it was found that black turbinate sign was present in the majority of the cases in MRI findings specific to sinonasal involvement of disease.…”