Teaching Case

48-year-old male patient with a five-day history of cough and fever. Past medical history was unremarkable. He also suffered from anosmia since three days. The patient was admitted to the hospital ward and discharged one week after admission with complete recovery.

Chest X-ray: In the early phase, the patients demonstrated moderate clinical manifestations, where lesions were limited to single or multiple areas; and were distributed along the subpleural areas

These findings indicated the characteristics of the spread of the lesions along the airway, starting with invasion of the bronchioles and alveolar epithelium of the cortical lung tissues, and extending gradually from the periphery to the centre.

Background:

Coronavirus is a large RNA virus family. Six subtypes have been identified [1]. SARS-CoV-2 is a new subtype whose genetic structure is 82% similar to SARS-CoV [2]. Basic reproduction number of COVID-19 was estimated to be 2.3 from reservoir to person and 3.58 from person to person which means that the expected number of secondary infections that result from introducing a single infected individual into an otherwise susceptible population was 3.58 [3]. The estimated reproduction numbers of severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) ranged from 2 to 5 and from 2.7 to 3.9, respectively [3] The mortality rate is less than commonly ascribed to severe community-acquired pneumonia (12 –15%) but more than seasonal influenza (0.1%) [4].

Clinical Perspective:

A better understanding of the underlying pathobiology is required. Wan et al. reported that residue 394 (glutamine) in the SARS-CoV-2 receptor-binding domain, corresponding to residue 479 in SARS-CoV, can be recognized by the critical lysine 31 on the human angiotensin converting enzyme ACE2 receptor [5]. Further analysis even suggested that SARS-CoV-2 recognizes human ACE2 more efficiently than SARS-CoV increasing the ability of SARS-CoV-2 to transmit from person to person [5].

Imaging Perspective:

The novel coronavirus is firstly causing interstitial damages and subsequently parenchymal changes. CT and plain chest radiography images could manifest different imaging features or patterns in COVID-19 patients with a different time course and disease severity [6, 7].

In the early phase, the patients demonstrated moderate clinical manifestations, where lesions like ground glass opacities were limited to single or multiple areas; and were distributed along the subpleural areas. These findings indicated the characteristics of the spread of the lesions along the airway, starting with invasion of the bronchioles and alveolar epithelium of the cortical lung tissues, and extending gradually from the periphery to the center.

Outcome:

Olfactory and taste disorders are well known to be related with a wide range of viral infections [8]. SARS-CoV has demonstrated in mice model a transneural penetration through the olfactory bulb [9]. Even our patient suffered from anosmia which has already been reported in COVID-19 [10]. Typical chest radiographs underlined the diagnosis of COVID-19, which was confirmed by RT-PCR.

Take home message:

Although chest radiograph is not very specific it is still the first imaging modality in COVID 19 patients. The present case demonstrated an unusual clinical manifestation with olfactory alterations. However multiple lung consolidations along the subpleural areas must be suspected for COVID 19.