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 Table of Contents  
Year : 2021  |  Volume : 2  |  Issue : 3  |  Page : 70-72

The spider web sign in the COVID lung

1 Consultant Physician, Ruby General Hospital, Kolkata, West Bengal, India
2 Consultant Physician, Desun Multispecialty Hospital, Kolkata, West Bengal, India

Date of Submission18-Nov-2020
Date of Decision05-Jun-2021
Date of Acceptance20-May-2021
Date of Web Publication28-Dec-2021

Correspondence Address:
Dr. Rudrajit Paul
15/5, Bose Pukur Road, Kolkata - 700 039, West Bengal
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jphpc.jphpc_12_20

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The COVID-19 infection causes a severe form of viral pneumonia in a proportion of the infected patients. Over the last 1 year, a lot of typical and atypical radiological changes in COVID pneumonia have been documented. These radiological appearances can help in the diagnosis of COVID infection even before genetic test results are available. While some of these signs are nonspecific and found in a lot of other infections, there are a few signs that have been newly described specifically during the current pandemic. Here, we present such a rare sign in a patient from Eastern India.

Keywords: Asian, COVID-19, ground-glass opacity, spider web, subpleural

How to cite this article:
Paul R, Som K. The spider web sign in the COVID lung. J Public Health Prim Care 2021;2:70-2

How to cite this URL:
Paul R, Som K. The spider web sign in the COVID lung. J Public Health Prim Care [serial online] 2021 [cited 2023 Feb 6];2:70-2. Available from: http://www.jphpc.org/text.asp?2021/2/3/70/333896

  Introduction Top

SARS-CoV-2 has emerged as a pandemic over the last 1 year.[1] This highly infectious respiratory virus causes a severe type of viral pneumonia only in a small fraction of the persons infected. However, in this proportion of patients, the disease can run a stormy course with high morbidity and mortality.

During an epidemic, especially when testing kits are in short supply, chest imaging can be an invaluable tool in reaching a provisional diagnosis of COVID infection. Furthermore, the reverse transcription polymerase chain reaction (RT-PCR) test takes time to yield results (typically 24–48 h), while chest imaging like high-resolution computed tomography (HRCT) thorax can be done within 10 min. Thus, during this epidemic, every clinician should be well versed in the HRCT appearance of the lung in COVID infection.

Most of the imaging features of the lung in this infection are nonspecific and common to any respiratory viral infection. They include consolidation, ground-glass opacity (GGO), and thickening of septae.[1] However, over the last 1 year, some typical features of the COVID lung have also been documented. These typical features are comparatively rare, but if present, can be a strong point in favor of presumptive COVID infection, diagnosis, even before RT-PCR results are available. We here present the report of one such rare radiological sign.

  Case Report Top

A 72-year-old man, without any comorbidity such as diabetes or hypertension, presented with high fever for 1 day. RT-PCR test of his nasal swab was positive for COVID-19. Simultaneous HRCT scan of the thorax on day 1 showed only scattered GGOs. The patient had no dyspnea, and he was admitted for observation. His initial blood reports were normal including a C-reactive protein (CRP) of 3 mg/L. He became afebrile on day 5; however, suddenly, on day 7 of diagnosis, he developed acute dyspnea with cough. A repeat HRCT scan of the thorax showed [Figure 1] areas of consolidation and reticular opacities in both lungs. Along with that, there were also triangular areas of GGO adjacent to the pleura looking like cobwebs at the corner of a wall [spider web sign; [Figure 1]]. Repeat blood tests showed CRP of >200 mg/L (N <5), interleukin-6 level of 125 pg/mL (N <7), and total leukocyte count of 14,000/cumm.
Figure 1: High-resolution computed tomography image of the lung in a COVID patient showing areas of reticular opacity (white arrow), consolidation (white arrowhead), and pleural-based angular ground-glass opacities (black arrows), the spider web sign

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The patient was treated with i.v. remdesivir (200 mg on day 1, followed by 100 mg OD for 10 days). Further, he was given i.v. dexamethasone as per the protocol. There was gradual improvement in his symptoms and oxygen demand also decreased. The patient did not need any ventilatory support. Repeat HRCT of the thorax after 10 days showed significant resolution of the imaging abnormalities.

  Discussion Top

The COVID-19 pandemic is still evolving, and scientists are in the process of documenting the various facets of this illness. With time, novel imaging changes in the COVID lung are also being discovered.

The spider web sign is such a novel radiological sign in COVID. This sign was first described by Wu et al.[1] In their series, they found 25% of the patients with this radiological pattern. This was a triangular or angular GGO under the pleura with internal net-like septal thickening. The adjacent pleura was also pulled and formed a spider-web-like appearance. This sign thus represents patchy peripheral lung involvement. However, whether this sign has any value in prognosis is still unknown.

Li et al., in their study of the computed tomography (CT) findings in severe COVID pneumonia, also documented this sign in around 25% of the patients.[2] They found that the sign was more prevalent in noncritical cases than in critical ones.[2] Presumably, critical cases of COVID show progression to consolidation in the chest and GGO (which forms the basis of the spider web sign) is absent.

Recently, a well-designed meta-analysis of the CT imaging features of 4121 COVID patients was published.[3] All of the studies included in this analysis were from China. In this, it was found that this new radiological sign was found in 39.5% of the cases (95% confidence interval 27.2%–52.6%). Hence, the authors have mentioned this as one of the most common signs in the COVID lung. However, the pathophysiology of this radiological change is still unknown. Further, it must be remembered that diagnosis of COVID infection does not depend on this one radiological change in the lung and other more common changes are usually present in addition. Absence of this sign, by no means, rules out COVID infection.

As far as published literature shows, this sign has mostly been described in Asian patients. In a series of 220 patients from Egypt, the sign was described only in 12 (5.5%) patients.[4] It has only rarely been described from Europe. Some authors do not consider this to be a separate sign but a variation of the “pleural retraction sign.”[5] Further, this sign has not been described in India till now.

This radiological sign must not be confused with another spider web sign that is found in the liver in  Budd-Chiari syndrome More Details.[6]

There are a lot of unanswered questions about this new sign. First, there are no data on the pathological nature of this lesion. Although some autopsy studies have been done, there is no study which specifically looks at this lesion. Second, is this a sign specific for COVID? Or is it found in other viral infections too, like swine flu or cytomegalovirus pneumonitis? And finally, none of the previous authors have followed this lesion radiologically to document its evolution. Does it get bigger and merge with other parenchymal GGO lesions? Or does it stay discrete? Further observation will be needed to better answer these questions.

We present this case to sensitize clinicians to the novel radiological findings in the COVID lung.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.


We would like to acknowledge The Medical Superintendent, Desun Hospital, Kolkata.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Wu J, Wu X, Zeng W, Guo D, Fang Z, Chen L, et al. Chest CT findings in patients with coronavirus disease 2019 and its relationship with clinical features. Invest Radiol 2020;55:257-61.  Back to cited text no. 1
Li K, Wu J, Wu F, Guo D, Chen L, Fang Z, et al. The clinical and chest CT features associated with severe and critical COVID-19 pneumonia. Invest Radiol 2020;55:327-31.  Back to cited text no. 2
Zhu J, Zhong Z, Li H, Ji P, Pang J, Li B, et al. CT imaging features of 4121 patients with COVID-19: A meta-analysis. J Med Virol 2020;92:891-902.  Back to cited text no. 3
Sabri YY, Nassef AA, Ibrahim IM, el Mageed MR, Khairy MA. CT chest for COVID-19, a multicenter study–Experience with 220 Egyptian patients. Egypt J Radiol Nucl Med 2020;51:144.  Back to cited text no. 4
Venugopal VK, Mahajan V, Rajan S, Agarwal VK, Rajan R, Syed S, et al. Systematic meta-analysis of CT features of COVID-19: Lessons from radiology. medRxiv. Available from: https://www.medrxiv.org/content/10.1101/2020.04.04.20052241v1. [Last accessed on 2020 Nov 17].  Back to cited text no. 5
Xiang H, Han J, Ridley WE, Ridley LJ. Spider's web sign: Budd-Chiari syndrome. J Med Imaging Radiat Oncol 2018;62:110.  Back to cited text no. 6


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