Utility of 2-Deoxy-2-[18F]fluoro-Dglucose positron emission tomography/computed tomography scan in the systemic evaluation of patients with post-COVID-19 endogenous presumed fungal endophthalmitis.

Abstract

A 48-year-old nondiabetic male presented with persistent breathlessness, cough, intermittent pyrexia, and grossly reduced vision in the right eye. Based on the available records, he had been diagnosed with COVID-19 earlier (based on a positive RT-PCR) and had received domiciliary care for an initial five days. Following clinical deterioration, he was admitted, treated with systemic steroids, antibiotics, and ventilatory support. Ten days post discharge, he developed a gross reduction in vision in the right eye (CF: 1 m). Five days later, he underwent a vitrectomy for endophthalmitis with intravitreal voriconazole (100 mcg), vancomycin (1 mg), and ceftazidime (2.25 mg) with a reported postoperative vision of 6/24 (20/80). Microbiology of the vitreous fluid for KOH, gram staining, and culture/sensitivity were reported as negative. He was readmitted in our tertiary care center on the 14th day postoperatively. On admission, he was afebrile, with tachycardia (heart rate: 91/min), dyspneic (respiratory rate: 21/minute) with inspiratory basilar crackles with decreased air entry bilaterally. His oxygen saturation was normal (99%). The visual acuity was HMCF in the right eye and 6/6 (20/20) in the left eye. Dilated fundus exam showed significant vitreous haze (3+) that obscured the fundus view [Fig. 1]. A large yellowish preretinal lesion was seen in the superonasal quadrant [Fig. 2]. The fundus of the left eye was normal.Figure 1: Fundus photo of the right eye revealing vitreous haze grade 3+Figure 2: Fundus photo revealing a yellow-white preretinal lesion in the superonasal quadrantBlood investigations included assessment of the hemoglobin (11.30 gm/dl), white cell counts (11,170/mm3), and serum creatinine (1.05 mg/dl), which were normal. Specific tests included C-reactive protein (45.56 mg/l), D-dimer (2910 ng/ml), and serum fibrinogen (590 mg/dl). Blood cultures for aerobic, anaerobic, and fungal cultures were negative. He underwent a whole-body 2-Deoxy-2-[18F]fluoro-D-glucose (FDG) Positron Emission Tomography/Computed Tomography (PET/CT) scan to detect a possible focus of infection. A high-grade uptake was seen in an area of patchy consolidation, and additional moderate grade uptake was seen in large cavitary lesions in each lung [Fig. 3]. Multiple nodular opacities through the rest of the lung fields demonstrated low-grade uptake. A CT-guided biopsy at an area of high uptake (right lung; lower lobe) was performed [Fig. 4]. Histopathological study showed extensive areas of necrosis enmeshed with broad aseptate hyphae. Scattered granulomas were also seen. The picture was consistent with invasive fungal infection. Fungal cultures of the lung biopsy revealed Rhizopus species. The isolates were analyzed by MALDI TOF MS (Matrix-assisted laser desorption ionization-time of flight-mass spectroscopy) to confirm a species identification of Rhizopus microsporus. The patient underwent two intravitreal amphotericin B injections (5 mcg, a week apart) along with an intravenous amphotericin B course (3 mg/kg/day) for six weeks, with no clinical improvement (perception of light only). Subsequent ultrasound examination revealed a large multilobular intraocular mass attached to the posterior pole with a thickened membrane in the mid-vitreous [Fig. 5]. The patient opted to be treated elsewhere and was discharged.Figure 3: (a-c) High-grade uptake (white arrowhead; SUV max 11.45) seen in patchy consolidation within the posterior aspect of the right lung lower lobe. Moderate grade uptake seen in large cavitary lesions in the right lung middle and lower lobes (red arrows; SUV max 7.8). (b-d) CT scans revealing multiple cavitary lesions of the right lung (red arrows)Figure 4: CT scan showing biopsy needle placement within the cavitary lesion (white arrowhead)Figure 5: Ultrasound image of the eye showing a large multilobular mass attached to the posterior pole and to a thickened mid-vitreal membranePost-COVID-19 endogenous endophthalmitis is increasingly being recognized, and identification of the systemic focus and its treatment is an integral part of treatment.[1] Fungal endophthalmitis due to mucor species has only rarely been reported.[2] The use of a FDG PET/CT scan allowed identification of a pulmonary focus and suggested potential sites of biopsy, thus increasing the possibility of a positive diagnosis. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.