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LETTER TO THE EDITOR
Differences on clinicopathological
profile from intraoral minor
salivary gland tumors around
the world
To the Editor:
We read with great interest the paper from Wang
et al.1 regarding intraoral minor salivary gland tumors
(IMSGT). This and our recently published article2 are
the largest clinicopathological studies on IMSGT re-
cently reported in the literature; both are based on the
last updated World Health Organization classification
of salivary gland tumors.3 As many IMSGT are rela-
tively uncommon lesions, large series are useful to
compare their incidence and sociodemographic and
clinical features, and to evaluate differences in specific
racial groups and geographic areas. When comparing
these 2 studies, one from North America and another
from Asia, we could identify some important differ-
ences. As both studies used similar diagnostic criteria,
personal histological interpretation criteria would not
justify all differences, most of them probably represent-
ing true racial, environmental, and geographical differ-
ences.
The first point was the frequency of the IMSGT
histological subtypes. Both studies reinforced that on
minor salivary glands, benign and malignant tumors
have an almost equal frequency. Some studies have
previously reported that pleomorphic adenoma (PA)
seems to have a higher prevalence among Japanese.4
According to the data of Wang et al.,1 PA and myoep-
ithelioma, sometimes interpreted as a spectrum of PA,
represented together 44% of all tumors from a total of
46% of benign tumors. In contrast, our findings re-
vealed that PA represented 33% of all tumors from a
total of 56% of benign tumors.2 This could be ex-
plained by the fact that cystadenomas and canalicular
adenomas represented 11% and 9% of all tumors, re-
spectively, in Pires et al.,2 in contrast to less than 1%
and 0%, respectively, in Wang et al.1 This should
indicate that cystadenomas and canalicular adenomas
are more common in the North American than Japanese
and Chinese populations (Table I).
Malignant IMSGT revealed some different features
in both studies as well. Mucoepidermoid carcinoma
(MEC) and adenoid cystic carcinoma (ACC) repre-
sented the most common malignant tumors, but their
136
prevalence was different in the 2 studies. Studies from
Japan have reported a greater incidence of adenoid
cystic carcinoma in comparison to mucoepidermoid
carcinoma,4 similar to the finding of Wang et al.,1 but
in contrast to most papers from Europe and America.2
Polymorphous low-grade adenocarcinoma seems to be
rare in Japan,4 but represented 5% of all IMSGT in both
studies.1,2 Other interesting findings were the higher
frequency of acinic cell adenocarcinoma in Pires et al.2
in contrast to the higher frequency of carcinoma, ex-
pleomorphic adenoma, and myoepithelial carcinoma in
Wang et al.1 These findings together reinforce that
there are also some differences in the frequency of
malignant IMSGT when comparing the American and
Asian populations (Table I).
Site distribution revealed that the palate, buccal mu-
cosa, and upper lip were the common locations of
IMSGT in both studies. Palate, the buccal mucosa, the
floor of mouth, the tongue, and the alveolar mucosa
were the common sites for malignant tumors. Salivary
gland tumors were mostly benign on the upper lip but
malignant on the lower lip. It is interesting to note that
in almost all of the common benign and malignant
tumors reported by Wang et al.,1 there was a marked
predilection for the palate, whereas this clear distribu-
tion was not highlighted by the results of Pires et al.2
Table I. Comparison on the most common benign and
malignant minor salivary gland tumors from Pires
et al.2 and Wang et al1
Pires et al. Wang et al.
Histological type n % n %
Benign 305 56 340 46
Pleomorphic adenoma 181 33 278 37
Canalicular adenoma 50 9 None None
Cystadenomas 58 11 6 �1
Myoepithelioma 1 �1 49 7
Malignant 241 44 397 54
Mucoepidermoid carcinoma 125 23 91 12
Adenoid cystic carcinoma 35 6 143 19
Polimorphous low-grade
adenocarcinoma
28 5 34 5
Acinic cell adenocarcinoma 21 4 7 �1
Adenocarcinoma NOS 21 4 41 6
Carcinoma ex-pleomorphic
adenoma
2 �1 22 3
Myoepithelial carcinoma 1 �1 24 3
NOS, not otherwise specified.
This could be even more evident when analyzing, for
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Volume 105, Number 2 Letter to the Editor 137
example, the site distribution of polymorphous low-
grade adenocarcinoma and acinic cell adenocarcinoma
on both studies (Table II).
Women were more often affected than men in the
great majority of histological subtypes from the data of
Pires et al.,2 except for adenocarcinoma not otherwise
specified (NOS). In contrast, malignant tumors were
more common in men in the study by Wang et al.,1
especially by the fact that adenocarcinoma NOS, car-
cinoma ex-pleomorphic adenoma, and myoepithelial
carcinoma showed a marked prevalence for men. It is
also interesting to call attention to the marked predilec-
tion for women of polymorphous low-grade adenocar-
cinoma and acinic cell adenocarcinoma in Pires et al.2
and the predilection of cystadenomas for men in Wang
et al.1 We also observed an interesting difference in the
mean age range for most histological subtypes in both
studies. On average, the mean age of Chinese patients1
was in the fifth decade of life, whereas most North
American patients were diagnosed in their sixth to
seventh decades of life.2 Retrospective studies usually
do not permit evaluation of symptom intervals, as this
Table II. Comparison on site distribution on the most
from Pires et al.2 and Wang et al1*
P
Histological type P BM
Benign
Pleomorphic adenoma 40 18
Malignant
Mucoepidermoid carcinoma 34 14
Adenoid cystic carcinoma 40 17
Polimorphous low-grade adenocarcinoma 39 18
Acinic cell adenocarcinoma 19 33
Adenocarcinoma NOS 43 14
P, palate; BM, buccal mucosa; L, lips; FM/AM, floor of mouth/alveo
*Numbers are expressed in %.
Table III. Comparison on gender and age distribution
gland tumors from Pires et al.2 and Wang et al1
P
Histological type M, % F
Benign 38
Pleomorphic adenoma 38
Cystadenomas 43
Malignant 39
Mucoepidermoid carcinoma 40
Adenoid cystic carcinoma 49
Polimorphous low-grade adenocarcinoma 18
Acinic cell adenocarcinoma 19
Adenocarcinoma NOS 57
NOS, not otherwise specified.
information is rarely reported on laboratory registries,
so it is difficult to interpret if the differences are due to
earlier detection of the disease or reflect a true regional
variation in age distribution (Table III).
In summary, IMSGT are a heterogeneous group of
tumors and large series are important to understand
their frequency and sociodemographic and clinical
individual characteristics. Reports from different
populations using the same diagnostic criteria are
essential to compare and estimate true racial and
geographical variations in these uncommon head and
neck tumors.
Fábio Ramôa Pires, DDS, PhD
Oral Pathology
State University of Rio de Janeiro
Rio de Janeiro, Brazil
Oslei Paes de Almeida, DDS, PhD
Oral Pathology
Piracicaba Dental School
State University of Campinas
on benign and malignant minor salivary gland tumors
al. Wang et al.
L FM/AM P BM L FM/AM
9 3 77 10 10 �1
1 22 58 12 8 19
6 29 57 12 6 12
1 11 82 6 6 6
3 5 43 14 14 29
5 38 39 17 2 37
cosa; NOS, not otherwise specified.
e most common benign and malignant minor salivary
al. Wang et al.
Mean age, y M, % F, % Mean age, y
58 48 52 41
51 48 52 44
61 67 33 46
62 54 46 49
55 41 59 43
59 46 54 50
69 50 50 52
58 43 57 54
70 78 22 50
comm
ires et
2
1
2
3
lar mu
on th
ires et
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62
62
57
61
60
51
82
81
43
Piracicaba, Brazil
OOOOE
138 Letter to the Editor February 2008
Gordon Pringle, DDS, PhD
Sow-Yeh Chen, DDS, PhD
Oral Pathology Section
Department of Pathology and Laboratory Medicine
Temple University School of Medicine
Philadelphia, Pennsylvania
REFERENCES
1. Wang D, Li Y, He H, Liu L, Wu L, He Z. Intraoral minor salivary
gland tumors in a Chinese population: a retrospective study on 737
cases. Oral Surg Oral Med OralPathol Oral Radiol Endod
2007;104:94-100.
2. Pires FR, Pringle GA, Almeida OP, Chen SY. Intra-oral minor
salivary gland tumors: a clinicopathological study of 546 cases.
Oral Oncol 2007;43:463-70.
3. Barnes L, Eveson JW, Reichart P, Sidransky D. World Health
Organization classification of tumours. Pathology and genetics—
head and neck tumors. Lyon: IARC Press; 2005.
4. Toida M, Shimokawa K, Makita H, Kato K, Kobayashi A,
Kusunoki Y, et al. Intraoral minor salivary gland tumors: a clin-
icopathological study of 82 cases. Int J Oral Maxillofac Surg
2005;34:528-32.
doi:10.1016/j.tripleo.2007.08.042
	Differences on clinicopathological profile from intraoral minor salivary gland tumors around the world
	To the Editor
	REFERENCES