Covid-19 Symptomatic Patients with Oral Lesions: Clinical and Histopathological Study on 123 Cases of the University Hospital Policlinic of Bari with a Purpose of a New Classification

Abstract

The aim of this study is to report on the oral lesions detected in 123 patients diagnosed at the University Hospital of Bari from October 2020 to December 2020, focusing on the correlation of clinical and pathological features in order to purpose a new classification.

Methods:
General and specialistic anamnesis were achieved and oral examination was performed. The following data were collected: age/gender, general symptoms and form of Covid-19, presence and features of taste disorders, day of appearance of the oral lesions, type and features of oral lesions and day of beginning of therapies. If ulcerative lesions did not heal, biopsy was performed.

Results:
Many types of oral lesions were found and classified into four groups considering the timing of appearance and the start of the therapies. Early lesions in the initial stages of Covid-19 before the start of therapies was observed in 65.9% of the patients. In the histopathological analysis of four early lesions, thrombosis of small and middle size vessels was always noticed with necrosis of superficial tissues.

Conclusion:
The presence of oral lesions in early stages of Covid-19 could represent an initial sign of peripheral thrombosis, a warning sign of possible evolution to severe illness. This suggests that anticoagulant therapies should start as soon as possible.

Full text

Journal of
Clinical Medicine
Article
Covid-19 Symptomatic Patients with Oral Lesions: Clinical and
Histopathological Study on 123 Cases of the University Hospital
Policlinic of Bari with a Purpose of a New Classification
Gianfranco Favia 1, Angela Tempesta 1, Giuseppe Barile 1, Nicola Brienza 2, Saverio Capodiferro 1,
Maria Concetta Vestito 2, Lucilla Crudele 3, Vito Procacci 3, Giuseppe Ingravallo 4, Eugenio Maiorano 4
and Luisa Limongelli 1, *


Citation: Favia, G.; Tempesta, A.;
Barile, G.; Brienza, N.; Capodiferro, S.;
Vestito, M.C.; Crudele, L.; Procacci, V.;
Ingravallo, G.; Maiorano, E.; et al.
Covid-19 Symptomatic Patients with
Oral Lesions: Clinical and
Histopathological Study on 123 Cases
of the University Hospital Policlinic
of Bari with a Purpose of a New
Classification. J. Clin. Med. 2021,10,
757. https://doi.org/10.3390/
jcm10040757
Academic Editor: Cheng-Chia Yu
Received: 29 January 2021
Accepted: 10 February 2021
Published: 13 February 2021
Publisher’s Note: MDPI stays neutral
with regard to jurisdictional claims in
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iations.
Copyright: © 2021 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
1Odontostomatology Unit, Department of Interdisciplinary Medicine, “Aldo Moro” University of Bari,
70124 Bari, Italy; gianfranco.favia@uniba.it (G.F.); angela.tempesta1989@gmail.com (A.T.);
g.barile93@hotmail.it (G.B.); capodiferro.saverio@gmail.com (S.C.)
2Covid-19 Intensive Care Unit, Department of Interdisciplinary Medicine, “Aldo Moro” University of Bari,
70124 Bari, Italy; nicola.brienza@uniba.it (N.B.); mconcetta.vestito@gmail.com (M.C.V.)
3Covid-19 Emergency Unit, Department of Emergency and Urgency, University Hospital Policlinic of Bari,
70124 Bari, Italy; lucilla.crudele@uniba.it (L.C.); v.procacci59@gmail.com (V.P.)
4Pathological Anatomy Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo
Moro, 70124 Bari, Italy; giuseppe.ingravallo@uniba.it (G.I.); eugenio.maiorano@uniba.it (E.M.)
*Correspondence: luisanna.limongelli@gmail.com
Abstract:
The aim of this study is to report on the oral lesions detected in 123 patients diagnosed
at the University Hospital of Bari from October 2020 to December 2020, focusing on the correlation
of clinical and pathological features in order to purpose a new classification. Methods. General
and specialistic anamnesis were achieved and oral examination was performed. The following data
were collected: age/gender, general symptoms and form of Covid-19, presence and features of taste
disorders, day of appearance of the oral lesions, type and features of oral lesions and day of beginning
of therapies. If ulcerative lesions did not heal, biopsy was performed. Results. Many types of oral
lesions were found and classified into four groups considering the timing of appearance and the
start of the therapies. Early lesions in the initial stages of Covid-19 before the start of therapies was
observed in 65.9% of the patients. In the histopathological analysis of four early lesions, thrombosis
of small and middle size vessels was always noticed with necrosis of superficial tissues. Conclusion.
The presence of oral lesions in early stages of Covid-19 could represent an initial sign of peripheral
thrombosis, a warning sign of possible evolution to severe illness. This suggests that anticoagulant
therapies should start as soon as possible.
Keywords: Covid-19; oral lesions; oral ulcers; classification
1. Introduction
Since the identification of the Severe Acute Respiratory Syndrome Coronavirus 2
(SARS-CoV-2) in December 2019 in Wuhan, China, millions of cases have been diagnosed
worldwide, with mortality rates ranging from 3% to 12% [
1
,
2
]. The Centers for Disease
Control and Prevention in the clinical course of the Coronavirus Disease 19 (Covid-19)
distinguished the following forms: asymptomatic infection, mild, moderate, severe and
critical illness [
1
]. In addition to fever, fatigue, dry cough, sore throat, breathing diffi-
culties, pneumonia and respiratory complications that often deteriorate to severe acute
respiratory syndrome, SARS-CoV-2 may cause plenty of other complications that involve
the kidney, heart, central and peripheral nervous system and gastrointestinal tract [
3
].
Although gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of
Covid-19 were clearly stated in [
4
] in April 2020, to the best of our knowledge, Chaux-
Bodard et al. described the first oral association with Covid-19 in a patient presenting an
J. Clin. Med. 2021,10, 757. https://doi.org/10.3390/jcm10040757 https://www.mdpi.com/journal/jcm

J. Clin. Med. 2021,10, 757 2 of 10
irregular ulcer on the dorsal side of the tongue [
5
]. After this report, many case reports fol-
lowed. White plaques, several painful ulcers, non-specific nodules, severe geographic and
fissured tongue, small blisters, petechiae, pustular enanthema, desquamative gingivitis,
angina bullosa and erythema multiforme-like lesions were described with not well-known
etiopathogenesis and unclear direct virus correlation [
6
–
11
]. While histopathological stud-
ies with a broad spectrum of skin dermatoses associated to Covid-19 were largely reported
in the current English literature [
12
], histopathological analysis of oral mucous lesions is
still not described.
The aim of this study is to report on the oral lesions detected in 123 patients diagnosed
at the University Hospital of Bari from October 2020 to December 2020, focusing on the
correlation of clinical and pathological features in order to purpose a new classification.
2. Materials and Methods
This study was carried out in accordance to the principles of the Declaration of Helsinki
and approved by the Independent Ethical Committee active in the University of Bari, Italy
(Study No. 4652, Prot. 66/CE); patients released informed consent for diagnostic and
therapeutic procedures and for possible use of the biologic samples for research purposes.
Patients included in the current study followed these inclusion criteria:
(1)
The presence of SARS-CoV-2 confirmed by reverse transcription polymerase chain
reaction (RT-PCR) after nasal and oropharyngeal swabs;
(2)
Adult patients hospitalized at the University Hospital Policlinic of Bari from October
2020 to December 2020.
Patients with certain pre-existing lesions, which means all those that were symp-
tomatic of pre-existing systemic and local conditions previously diagnosed and well-known
to the patients, as well as patients with traumatic lesions, were excluded. Because of their
home self-confinement, people with the asymptomatic and mild forms were excluded too.
All the patients were visited by three oral pathologists properly dressed in personal
protective equipment; those with moderate form were visited at the Emergency Unit of
University Hospital Policlinic of Bari, while the others with severe and critical illness were
visited at the Covid-19 Intensive Care Unit of the University Hospital Policlinic of Bari.
General and specialistic anamnesis were achieved from patients or derived from
medical records if the patient was unable to communicate. The following data were
collected: age and gender, general symptoms of Covid-19, form of Covid-19 according to
WHO classification [
1
], presence of taste disorders, day of appearance of the oral lesions
after the onset of general/systemic symptoms and day of beginning of therapies. With
respect to taste disorders the authors distinguished real dysgeusia, hypogeusia and ageusia.
After the WHO eight-step intraoral examination, the following clinical data were
collected: type of lesion and features (site, size and numbers), symptoms referred and
quality of oral hygiene. Where necessary, cytological smears were collected by brushing and
following 80% alcoholic spray fixation and stained with Papanicolaou stain and Periodic
Acid Shiff (PAS).
The following topical treatments were administered:
1.
Hyaluronic acid gel and chlorhexidine 2% mouthwash or gel (twice a day) for 14 days
in patients with ulcero-erosive lesions [13,14];
2.
Miconazole Nitrate twice a day in patients with cytological diagnosis of candidia-
sis [15];
3. Tranexamic acid for local hemorrhages [16].
If ulcerative lesions did not heal after 14 days in patients with the mild form of Covid-
19, biopsy was performed under local anesthesia, with prior rinsing with chlorhexidine 2%
mouthwash of at least one minute.
All surgical samples were promptly fixed in neutral-buffered formalin for 48 h and
sent to the Pathological Anatomy Unit of the University of Bari, then embedded in paraffin,
sectioned at 4 µm thickness and stained with hematoxylin-eosin (H&E).

J. Clin. Med. 2021,10, 757 3 of 10
Finally, lesions were classified into four groups:
1.
Probably pre-existing conditions: all the para-physiological lesions endemic in the
general population;
2.
SARS-CoV-2-related lesions. The authors considered lesions as virus-related when
they appeared together with general symptoms or within one week after the onset of
general symptoms and always before the beginning of therapies;
3.
Treatment-related lesions: lesions that appeared after the start of the Covid-19 specific
therapies;
4. Lesions mainly related to poor oral hygiene.
All the diagnostic-therapeutic protocol was detailed in a flowchart (Figure S1).
3. Results
3.1. Patients Data
A total of 123 patients were enrolled in this study, 70 M and 53 F (M:F ratio 1,3:1) with
a median age of 72 years. Patient data are summarized in Table 1.
3.2. Oral Manifestations
Ulcerative lesions (65–52.8%) were the most frequently detected injury. They often
were painful and presented as single (40%) (Figure 1a,b,c) or multiple (60%) lesions.
The latter could occur with a herpetiform figured aspect (Figure 1d) or with a diffuse
erythematous base with evident multiple apthoid necrotic lesions coalescing in larger
ulcerative areas with yellowish fibrin covering, globally resembling erythema multiforme-
like disease (Figure 1e,f). When ulcers or larger necrotic areas involved the cutaneous
side of the lips, they evolved in crusts. Only in four cases, in which the authors noticed a
delay in healing (>14 days), biopsy was performed. These lesions were mainly located on
the tongue, palate, lip and cheek. In seven cases, the ulcerative lesions were preceded by
blisters as referred by patients. In 92% of the cases the ulcerative lesions appeared together
with general symptoms or within one week after the onset of general symptoms, then
defined as early.
J. Clin. Med. 2021, 10, x FOR PEER REVIEW 5 of 10
Treatment-related lesions
Late ulcerative lesions, late erythema multiforme-like le-
sions, candidiasis, angina bullosa, spontaneous oral hem-
orrhage, petechiae
Lesions related to poor oral hygiene Ulcero-necrotic gingivitis
A total of 65.9% of the patients showed lesions definable as “Early”. This means that
they appeared together with the onset of general symptoms or within one week and al-
ways before the beginning of Covid-19-specific therapies.
Figure 1. Single ulcerative lesions with diameter larger than 1 cm located in different sites (a,b) with associated petechiae
(c).Multiple ulcerative lesions with erythema multiforme-like aspect and tendency to coalesce (e,f) and herpetiform-like
aspect (d).
Figure 2. Red candidiasis median rhomboid glossitis-like (a); diffuse white candidiasis in an intu-
bated patient (b); hyperplasia of the lingual papillae (c); angina bullosa of the cheek with associ-
ated petechiae (d).
3.3. Taste Disorders
Figure 1.
Single ulcerative lesions with diameter larger than 1 cm located in different sites (
a
,
b
) with associated petechiae (
c
).
Multiple ulcerative lesions with erythema multiforme-like aspect and tendency to coalesce (
e
,
f
) and herpetiform-like
aspect (d).

J. Clin. Med. 2021,10, 757 4 of 10
Table 1. Patient data.
Form of Covid-19 N. of
Patients Age (Mean Value) General Symptoms Type of Oral
Lesions
Oral
Symptoms Day of Appearance Taste
Disorders
MODERATE 95 (77%) 63
Fever > 39 ◦C, anosmia, cough,
sore throat, congestion and
runny nose, nausea or vomiting,
muscle and body aches,
dermatologic manifestation,
pneumonia
- Geographic tongue (5)
- Fissured tongue (4)
- Ulcerative lesion (51)
- Blisters (14)
- Hyperplasia of papillae (33)
- Angina bullosa (8)
- Candidiasis (18)
- Ulcero-necrotic gingivitis (1)
- Petechiae (4)
- Pain
- Burning
- Bleeding
-
Difficulty to chew-
ing and swallow
- T *: 25 (26.4%)
- W **: 39 (41%)
- Z ***: 31 (32.6%)
87%
SEVERE 21 (17%) 74
Fever >39 ◦C, anosmia, cough,
sore throat, congestion and
runny nose, nausea or vomiting,
muscle and body aches,
dermatologic manifestation,
severe pneumonia, Dyspnea and
hypoxia (SpO2 < 90%); severe
respiratory distress
- Geographic tongue (2)
- Fissured tongue (1)
- Ulcerative lesion (11)
- Blisters (5)
- Hyperplasia of papillae (13)
- Angina bullosa (2)
- Candidiasis (4)
- Ulcero-necrotic gingivitis (2)
- Petechiae (6)
- Pain
- Burning
- Bleeding
-
Difficulty to chew-
ing and swallow
- T *: 4 (19%)
- W **: 11 (52.4%)
- Z ***: 6 (28.6%)
88%
CRITICAL 8 (6%) 81 Acute respiratory distress
syndrome, multiorgan failure
- Ulcerative lesion (3)
- Hyperplasia of papillae (2)
- Angina bullosa (1)
- Candidiasis (6)
- Ulcero-necrotic gingivitis (4)
- Petechiae (4)
- Spontaneous oral hemorrhage (1)
Not possible to achieve - T *: 1
- W **: 1
- Z ***: 6
83%
* T: oral lesions that appeared together with the onset of general symptoms. ** W: oral lesions that appeared within one week after the onset of general symptoms and before Covid-19-specific therapies. *** Z:
oral lesions that appeared after one week of the onset of general symptoms or after therapies.

J. Clin. Med. 2021,10, 757 5 of 10
Candidiasis was noticed in 28 patients (22.7%), most of which were red forms (21)
located on the tongue, mainly with median rhomboid glossitis-like appearance (Figure 2a),
and palate followed by white forms (7) (Figure 2b). The former were principally highlighted
in the moderate forms of Covid-19, while the latter were often seen in intubated patients
with severe and critical illness. The symptoms, if referred, associated with candidiasis
were pain and overall burning. A good recovery of the lesions was observed with topical
antifungal therapy (miconazole nitrate twice a day).
J. Clin. Med. 2021, 10, x FOR PEER REVIEW 5 of 10
Treatment-related lesions
Late ulcerative lesions, late erythema multiforme-like le-
sions, candidiasis, angina bullosa, spontaneous oral hem-
orrhage, petechiae
Lesions related to poor oral hygiene Ulcero-necrotic gingivitis
A total of 65.9% of the patients showed lesions definable as “Early”. This means that
they appeared together with the onset of general symptoms or within one week and al-
ways before the beginning of Covid-19-specific therapies.
Figure 1. Single ulcerative lesions with diameter larger than 1 cm located in different sites (a,b) with associated petechiae
(c).Multiple ulcerative lesions with erythema multiforme-like aspect and tendency to coalesce (e,f) and herpetiform-like
aspect (d).
Figure 2. Red candidiasis median rhomboid glossitis-like (a); diffuse white candidiasis in an intu-
bated patient (b); hyperplasia of the lingual papillae (c); angina bullosa of the cheek with associ-
ated petechiae (d).
3.3. Taste Disorders
Figure 2.
Red candidiasis median rhomboid glossitis-like (
a
); diffuse white candidiasis in an intubated
patient (
b
); hyperplasia of the lingual papillae (
c
); angina bullosa of the cheek with associated
petechiae (d).
Blisters were detected in 19 patients (15.4%). They suddenly collapsed into superficial
erythematous-ulcerative lesions and were mainly located on the tongue and palate; two
cases were associated with pain and low bleeding. They were often seen within the first
week after the onset of general symptoms.
Hyperplasia of papillae was highlighted in 48 cases (39%). It was always present in
patients with taste disorders and appeared as red enlargement of the papillae both on the
dorsum and on the sides of the tongue (Figure 2c).
Petechiae were noticed in 14 cases (11.4%). Frequently asymptomatic, they were
located on the hard and soft palate and tongue. They mostly appeared after the start of
therapies often in association with angina bullosa (Figure 2d).
Ulcero-necrotic gingivitis was unmasked in seven patients mainly in those with
critical illness with poor oral hygiene due to the lack of teeth brushing. Gingivo-parodontal
bleeding was often detected.
Angina bullosa was principally observed after the beginning of therapies, mainly
appeared with brown-black single-multiple bullae, and it was located on the soft palate,
tongue and cheek (Figure 2d).
Geographic tongue and fissured tongue occurred, respectively, in seven and five
patients (5.6% and 4%). They were asymptomatic and probably pre-existing.
Spontaneous oral hemorrhage happened in only one patient (0.8%) with critical illness
under anticoagulant therapy, and the bleeding derived from sublingual varices.
Considering the features of the lesions, the timing of presentations and the therapies
administered, the lesions are classified in Table 2.

J. Clin. Med. 2021,10, 757 6 of 10
Table 2. Classification of lesions.
Probably Pre-Existing Conditions Geographic Tongue, Fissured Tongue
Sars-CoV-2-related lesions Early ulcerative lesions, blisters, early erythema
multiforme-like lesions, petechiae
Treatment-related lesions
Late ulcerative lesions, late erythema
multiforme-like lesions, candidiasis, angina bullosa,
spontaneous oral hemorrhage, petechiae
Lesions related to poor oral hygiene Ulcero-necrotic gingivitis
A total of 65.9% of the patients showed lesions definable as “Early”. This means that
they appeared together with the onset of general symptoms or within one week and always
before the beginning of Covid-19-specific therapies.
3.3. Taste Disorders
Dysfunction of the taste was noticed in all three groups of patients with a percentage
higher than 80%. Particularly, real dysgeusia, intended as changes in taste discrimination
(i.e., perception of bitter flavor rather than sweet or salty flavor), was noticed in 64% of
patients, hypogeusia in 27% and ageusia in 9%.
Dysgeusia was always referred as one of the first symptoms.
3.4. Histopathological Analysis
From a histopathological point of view, it is possible to highlight different features
depending on whether the analyzed part of the ulcer is central or peripheral.
In the central necrotic-ulcerated parts, it denotes the complete lack of epithelial cover-
ing with a superficial layer of fibrin-enclosed basophilic debris (from alimentary and tissue
origin), and microorganisms cover underlying sub-epithelial tissues showing prominent
vascular hyperplasia (Figure 3a), perivascular hemorrhage and lymphomonocytes infiltra-
tion. In the deeper tissues this infiltrate has three main patterns: (1) superficial band-like
lichenoid appearance (Figure 3a,b); (2) perivascular often with dense sleeve-like pattern
(Figure 3c) (around small and medium size vascular structures); (3) peri-glandular, around
lobules of minor salivary glands. Thrombotic vascular occlusion of small and medium size
vascular structures is a frequent feature, in small vessels mainly with total occlusion and in
larger vessels with partial occlusion (Figure 3d,e,f).
In the peripheral parts, corresponding to the epithelial covered border of the ulcers,
the histopathological analysis revealed epithelial lesions: spongiosis, edema, leukocytosis,
necrotic keratinocytes and presence of activated Langerhans cells (Figure 3e); tongue papil-
lae showed a global hyperplastic aspect with lymphomonocytic infiltration and vascular
hyperplasia.

J. Clin. Med. 2021,10, 757 7 of 10
J. Clin. Med. 2021, 10, x FOR PEER REVIEW 6 of 10
Dysfunction of the taste was noticed in all three groups of patients with a percentage
higher than 80%. Particularly, real dysgeusia, intended as changes in taste discrimination
(i.e., perception of bitter flavor rather than sweet or salty flavor), was noticed in 64% of
patients, hypogeusia in 27% and ageusia in 9%.
Dysgeusia was always referred as one of the first symptoms.
3.4. Histopathological Analysis
From a histopathological point of view, it is possible to highlight different features
depending on whether the analyzed part of the ulcer is central or peripheral.
In the central necrotic-ulcerated parts, it denotes the complete lack of epithelial cov-
ering with a superficial layer of fibrin-enclosed basophilic debris (from alimentary and
tissue origin), and microorganisms cover underlying sub-epithelial tissues showing
prominent vascular hyperplasia (Figure 3a), perivascular hemorrhage and lymphomono-
cytes infiltration. In the deeper tissues this infiltrate has three main patterns: (1) superficial
band-like lichenoid appearance (Figure 3 a,b); (2) perivascular often with dense sleeve-
like pattern (Figure 3c) (around small and medium size vascular structures); (3) peri-glan-
dular, around lobules of minor salivary glands. Thrombotic vascular occlusion of small
and medium size vascular structures is a frequent feature, in small vessels mainly with
total occlusion and in larger vessels with partial occlusion (Figure 3 d,e,f).
Figure 3. H&E Magnification 40×: superficial band-like lichenoid appearance of the inflammatory infiltrate with promi-
nent vascular hyperplasia (a); H&E Magnification 150×: lympho-monocytes sub-epithelial infiltrate and edema, keratino-
cyte necrosis, and activation of Langerhans cells (b); H&E Magnification 180×: lympho-monocellular perivascular infiltra-
tion (c); H&E magnification 100×: Presence of multiple micro-thrombi (yellow arrows) of sub-epithelial small vessels (d);
H&E Magnification 120×: total occlusion of a middle-size sub-epithelial vessel with initial organization of the thrombus
(e); H&E Magnification 140×: partial occlusion of a deep vessel (yellow circle) and perivascular secondary fibrosis (f).
Figure 3.
H&E Magnification 40
×
: superficial band-like lichenoid appearance of the inflammatory infiltrate with prominent
vascular hyperplasia (
a
); H&E Magnification 150
×
: lympho-monocytes sub-epithelial infiltrate and edema, keratinocyte
necrosis, and activation of Langerhans cells (
b
); H&E Magnification 180
×
: lympho-monocellular perivascular infiltration
(
c
); H&E magnification 100
×
: Presence of multiple micro-thrombi (yellow arrows) of sub-epithelial small vessels (
d
); H&E
Magnification 120
×
: total occlusion of a middle-size sub-epithelial vessel with initial organization of the thrombus (
e
); H&E
Magnification 140×: partial occlusion of a deep vessel (yellow circle) and perivascular secondary fibrosis (f).
4. Discussion
The coronavirus 2019 disease is a viral infection with multiorgan manifestations and
variable severity of complications [
11
]. Although prevalence of dermatological manifes-
tation is already reported [
17
], the prevalence of oral lesions is still unknown probably
because oral cavity is not examined in Covid-19 patients. Since Chaux-Bodard et al. [
5
] de-
scribed the first oral manifestation associated with Covid-19, many reports were published
with plenty of lesions described. The most frequently detected oral manifestation is ulcer
(54.1%) [
18
], although white plaque, severe geographic and fixtured tongue, petechiae,
nodules, reddish macules, angina bullosa, blisters, necrotizing periodontal disease and
erythema multiforme-like lesions were also described [
19
–
22
]. In this study, most detected
lesions were ulcers (52.8%), both single and often multiple, with a tendency to merge into
large necrotic areas. The blisters were detected in 15.4% of cases and referred in anamnesis
in about 10% of patients with early ulcerative lesions. Different types of candidiasis were
also diagnosed in a pool of 28 patients.
Seirafianpour et al. [
23
], in a systematic review of dermatologic Covid-19 disorder,
applied an interesting distinguishment of skin lesions into virus-related lesions, virus-
treatment related lesions and pre-existing lesions that could be exasperated by Covid-19
infection.
Along the lines of Seirafianpour et al., the authors decided to categorize lesions into
four groups considering the following factors: the possibility they were pre-existing, time of

J. Clin. Med. 2021,10, 757 8 of 10
onset of oral lesion compared to the appearance of general symptoms and start of therapy,
quality of oral hygiene, and probably plaque-related conditions. The first group comprised
“Probably pre-existing lesions”, which means conditions underestimated by patients, but
in all likelihood already present at the moment of Covid-19 diagnosis. Indeed, geographic
tongue and fissured tongue have a varied prevalence in the general adult population up to
about 13% and 30%, respectively, and were often asymptomatic and underestimated by
patients [
24
]. Considering the high prevalence in the general adult population, the fact that
they were asymptomatic and not well known by the patients, the authors decided to insert
geographic and fissured tongue in the first group.
The second group included “SARS-CoV-2-related lesions”. The authors decided to
enclose in this group all the lesions that appeared together with the general symptoms
within one week and always before the start of Covid-19-specific therapies. Considering this
definition, some type of lesions, such as ulcerative ones or petechiae, were distinguished in
early and late stages and allocated in different groups. The early petechiae were associated
with vasculitis caused by SARS-CoV-19. The “Early” lesions belonging to this group were
detected in 65.9% of the patients.
The third group included treatment-related lesions, which means all the lesions that
appeared after the beginning of therapy and that were also related to multiorgan failures
in several critical cases. This group enclosed late petechiae and angina bullosa mainly
related to anticoagulant therapies and candidiasis related to corticosteroid and antibiotic
combined therapies.
Finally, the fourth group included lesions associated with poor oral hygiene qual-
ity. Indeed, although intubated patients received mouthwash with a solution filled with
chlorhexidine (2%, three times a day), the lack of mechanical teeth brushing caused the
presence of abundant plaque underlying the ulcero-necrotic gingivitis.
In view of the above, the authors primarily considered the lesions of the second group.
Four patients with early primary large necrotic area (enclosed in group 2) that did not
heal within 14 days underwent biopsy in order to understand the physio-pathological
mechanism underlying the formation of such big ulcers in an early stage of Covid-19.
Gianotti et al. [12] described the histopathology of skin Covid-19 lesions with a spec-
trum of findings that ranged from mild spongiosis of the epithelial layer to the important
situation of vasculitis and extravasation of red blood cells.
To the best of our knowledge, this is the first study that widely describes the histologi-
cal aspect of oral SARS-CoV-2- related lesions. The principal phenomenon that presents
both in peripheral and central parts of “Early” oral necrotic areas is the thrombotic vascular
occlusion of small and medium size vascular structures. Where the occlusion is complete
or almost complete, necrosis of the superficial layers occurs with a wide inflammatory
reaction in the deeper tissues organized in three different types of infiltration: (1) superfi-
cial band-like lichenoid appearance; (2) perivascular; (3) peri-glandular. At the periphery,
where partial occlusion is observed, it is possible to denote signs of epithelial suffering
with spongiosis, edema, leukocytosis, necrotic keratinocytes and activation of Langerhans
cells with vascular hyperplasia in the deeper tissue.
Chemosensitive disorders, both olfactory and gustatory, emerged as highly prevalent
symptoms during Covid-19. The clinical onset of chemosensitive disorders occurs char-
acteristically in the very early stages of the symptomatic infection, generally in the first
three days. The pathophysiological mechanisms leading to the olfactory and gustatory
dysfunctions in COVID-19 infection are still unknown [
25
]. Two main theories were dis-
cussed in the current Covid-19-related literature. On the one hand, it is possible that viruses
could infect peripheral neurons using the cell machinery of active transport to access the
central nervous system [
4
], and on the other hand, inhibition of the ACE-2 receptor is
possible. In fact, it is well known that ACE2 inhibitors can induce ageusia with a complex
mechanism that involves G-protein-coupled protein and sodium channel present in the
taste buds. SARS-CoV-2, infecting the cells and binding these receptors, could inactivate

J. Clin. Med. 2021,10, 757 9 of 10
the latter, blocking the transformation of chemical gustatory signals into action potential
and consequently the sensory perception of taste [25].
In this study, dysfunction of the taste was noticed in all three groups of patients with
a percentage higher than 80%, and it was always referred as one of the first symptoms.
The authors preferred to use the term taste dysfunction instead of dysgeusia because the
spectrum of taste alterations was broad. In 64% of the patients with taste dysfunction real
dysgeusia was noticed, intended as the changes in taste discrimination (i.e., perception
of bitter flavor rather than sweet or salty flavor). Hypogeusia and ageusia, intended as
reduction or complete lack of taste, were less frequent and, respectively, highlighted in 27%
and 9%.
This research is, however, subject to potential limitations. This is an observational
descriptive study with a brief follow-up of the patients. The authors noticed the lack of
previous research studies involving a big sample like that described in this article. In fact,
articles about oral lesions in Covid-19 patients published in the current literature are case
reports or small series. Moreover, the collection of data for those patients intubated was
achieved from medical records and not directly from the patients, so it is possible that some
data are not complete.
Surely, further studies should be conducted, better if multicenter, in order to reduce
these limitations at most.
5. Conclusions
This study on a large series highlighted that oral lesions in more than half of cases
(65.9%) occurred in the early stage of Covid-19 before the beginning of specific therapies.
Moreover, this study has unearthed that the physio-pathological mechanism, underlying
the formation of early oral lesions, is the thrombosis of sub-epithelial and deeper vessels.
Therefore, the presence of oral lesions could represent an initial sign of peripheral thrombo-
sis, a warning sign of possible evolution to severe illness. This suggests that anticoagulant
therapies should be started as soon as possible.
Supplementary Materials:
The following are available online at https://www.mdpi.com/2077-038
3/10/4/757/s1, Figure S1: FC1. Diagnostic therapeutic protocol of oral lesions in Covid 19 patients.
Author Contributions:
Conceptualization, L.L., A.T., and G.F.; methodology, G.F.; validation, N.B.,
V.P. and E.M.; formal analysis, A.T., S.C. and L.L.; investigation, A.T., G.B. M.C.V., and L.C.; re-
sources, L.L. and S.C.; data curation, L.L., G.F. and G.I.; writing—original draft preparation, L.L.;
writing—review and editing, L.L. and G.F.; visualization, N.B. and V.P.; supervision, E.M.; project
administration, G.F. All authors have read and agreed to the published version of the manuscript.
Funding: This research received no external funding.
Institutional Review Board Statement:
The study was conducted according to the guidelines of the
Declaration of Helsinki and approved by the Institutional Review Board (or Ethics Committee) of the
University of Bari, Italy (Study No. 4652, Prot. 66/CE).
Informed Consent Statement:
Informed consent was obtained from all subjects involved in the
study.
Conflicts of Interest: The authors declare no conflict of interest.
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