“Striking the Owl’s Eye” in COVID-19 Pneumonia: A Case Report
Corresponding Author: Anand Rajendran, Department of Respiratory Medicine, Velammal Medical College Hospital and Research Institute, Madurai, Tamil Nadu, India, Phone: +91 9524108802, e-mail: firstname.lastname@example.org
Received on: 01 September 2023; Accepted on: 25 September 2023; Published on: 30 October 2023
Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) belonging to the genus Betacoronavirus. Nasopharyngeal swab reverse transcription polymerase chain reaction (RT-PCR) of viral nucleic acid is considered the reference standard test for the diagnosis of COVID-19, however, in patients with false-negative RT-PCR results, high-resolution computed tomography (HRCT) scan of thorax plays an important role in diagnosing COVID-19 pneumonia. We have recently identified an atypical radiological finding on the HRCT scan of a patient with COVID-19 which we believe has not been described before in published literature. We have aptly named this radiological sign an “Owl’s eye sign.”
How to cite this article: Arshad AM, Ayub II, Rajendran A, et al. Striking the Owl’s Eye” in COVID-19 Pneumonia: A Case Report. Indian J Respir Care 2023;12(3):284–286.
Source of support: Nil
Conflict of interest: None
Patient consent statement: The author(s) have obtained written informed consent from the patient for publication of the case report details and related images.
Keywords: Case report, Coronavirus disease 2019, High-resolution computed tomography thorax, Reverse halo sign, Severe acute respiratory syndrome coronavirus 2
Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) belonging to the genus Betacoronavirus. Nasopharyngeal swab reverse transcription polymerase chain reaction (RT-PCR) of viral nucleic acid is considered the reference standard test for the diagnosis of COVID-19; however, in patients with false-negative RT-PCR results, high-resolution computed tomography (HRCT) scan of thorax plays an important role in diagnosing COVID-19 pneumonia. Various radiological signs were described on the HRCT scans done for COVID-19 patients during the pandemic. We have recently identified an atypical radiological finding on the HRCT scan of a patient with COVID-19 which we believe has not been described before in published literature. We have aptly named this radiological sign an “Owl’s eye sign.”
A 33-year-old gentleman presented to the emergency room with fever, breathing difficulty, and myalgia for 3 days. Clinical examination revealed fever with a temperature of 100° F, heart rate of 90/minute, tachypnoea with respiratory rate of 23/minute, and room air saturation of 89%. Blood pressure was normal. Respiratory system examination revealed crepitations bilaterally on auscultation. Other system examinations were normal.
His blood investigations revealed a total leukocyte count of 11,700 cells/dL (normal range of 4,000–11,000 cells/mm) with a neutrophil predominance of 86.6%, C-reactive protein of 7.7 mg/dL (normal range—0–0.8 mg/dL), and D-dimer of 0.61 mg/L (normal range—<0.55 mg/L), with normal blood sugar, liver and renal parameters. A nasopharyngeal swab for RT-PCR for SARS-CoV-2 taken at the emergency turned out to be positive. Chest X-ray anteroposterior view revealed bilateral coarse lung markings with reduced lung volumes (Fig. 1). HRCT scan of the chest revealed bilateral diffuse ill-defined subpleural ground-glass opacities and lower lobe perilobular consolidation with interlobular septal thickening suggestive of organizing pneumonia with a CT severity score 32 out of 40 (severe) (Fig. 2).
Additionally, areas of central clearing with persisting centrilobular nodule and surrounded by perilobular consolidation, a variant of organizing pneumonia called Bull’s eye sign, was identified in one coronal section (Fig. 2B) at the level of arch of aorta, we can see coalescing two Bull’s eye sign, with erasure of the perilobular thickening running between them, leading to two centrilobular nodules surrounded by a clear area which in turn is surrounded by consolidation overall, Mimicking an Owl’s eye (Fig. 2A). The patient was initiated on 3 L of oxygen via nasal prongs along with intravenous methylprednisolone (60 mg once daily) and subcutaneous enoxaparin (40 mg twice daily). His hospital stay was complicated by worsening hypoxemia requiring intensive care transfer and initiation of high-flow nasal cannula therapy on the third day of hospitalization. Subsequently, his hypoxemia improved and he was weaned off to low-flow oxygen therapy and shifted to the ward after 8 days of intensive care unit care. He was gradually weaned off oxygen and discharged after a prolonged hospital stay of 1 month.
Diagnosis of COVID-19 in RT-PCR-negative suspect patients is often challenging and HRCT thorax helps in the early diagnosis of such cases with an overall sensitivity of 98%.1 The two most common radiological features seen in COVID-19 patients are ground-glass opacities and consolidation. Ground-glass opacities are multifocal, bilateral, peripheral, and subpleural in distribution and are predominantly seen in the lower lobes.2-4 Ground-glass opacities are not seen alone often accompanied by other radiological signs such as consolidation and reticular changes with interlobular septal thickening predominantly affecting the lower lobes.
A reverse halo sign or atoll sign is a radiological finding in which there will be central ground-glass opacity surrounded by either a complete or crescentic-shaped denser consolidation.5 The presence of reverse halo is highly variable, Bai et al.6 in their study revealed that the reverse halo sign was present in 5% of 219 patients with COVID-19 but its incidence was much lower in other studies. This sign usually indicates the disease progression due to a consolidation developing around ground-glass opacity or absorption of a lesion leaving a decreased intensity in the center, but this sign is nonspecific and can also be seen in other conditions like cryptogenic, noncryptogenic organizing pneumonia, invasive fungal infections as well as lung malignancy.
Inside the ground-glass opacities were focal areas with central ground-glass nodules surrounded by an outer ring of ground-glass lesions with an inner ring of air commonly termed Bullseye. Anatomically, the outer ring of the ground-glass lesions was perilobular, while the central ground-glass nodules of the Bullseyes were centrilobular in origin.7 The inner rings of air within the Bullseye denote the sparing of the remnant pulmonary lobules. When two of these Bullseye coalesce together as present in this case, they resemble the appearance of an Owl’s eye, hence, our coining of the term “Owl’s eye sign.”
The presence of perivascular inflammation is usually seen as a central nodular opacity and when dense may represent a focal dilatation of the pulmonary artery, we suggest that there is a possibility that organizing pneumonia can involve both center and periphery of the secondary lobule with peribronchial vascular involvement.8
Literature reveals that the autopsy of these COVID-19 patients usually represents diffuse alveolar damage with endothelial dysfunction and hyaline membrane formation,9 cellular infiltration, and organization.10 Early stages of ground-glassing usually represent the early exudative phase,11 while the reverse halo sign, Bullseye sign, and the Owl’s eye sign usually represent the late organizing stage of the disease.
As far as our knowledge and review of literature is concerned this Owl’s eye sign has never been discussed nor published in any journals.
The “Owl’s eye sign” represents areas of organizing pneumonia, the late stage of the disease commonly manifesting as a reverse halo sign.
Anand Rajendran https://orcid.org/0000-0002-0823-2426
2. Pan Y, Guan H, Zhou S, et al. Initial CT findings and temporal changes in patients with the novel coronavirus pneumonia (2019-nCOV): a study of 63 patients in Wuhan, China. Eur Radiol 2020;30(6):3306–3309. DOI:10.1007/s00330-020-06731-x
6. Bai HX, Hsieh B, Xiong Z, et al. Performance of radiologists in differentiating COVID-19 from non-covid-19 viral pneumonia at chest ct. Radiology 2020;296(2):E46–E54. DOI: 10.1148/radiol.2020200823
11. Wong K, Antonio GE, Hui DS, et al. Thin-section CT of severe acute respiratory syndrome: evaluation of 73 patients exposed to or with the disease. Radiology 2003;228(2):395–400. DOI: 10.1148/radiol.2283030541
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