This document summarizes the clinicopathologic characteristics and cathepsin K (CTSK) expression patterns in 45 salivary gland carcinoma (SGC) cases. The key findings are: - CTSK expression was detected in carcinoma cells and sometimes stromal cells, but not normal salivary gland tissue. Metastatic SGC cells in lymph nodes were also CTSK-positive. - 82.2% of cases showed positive CTSK expression, with 51.1% exhibiting strong expression. Higher CTSK expression correlated with higher histologic grade, larger tumor size, positive nodal involvement, distant metastasis, and recurrence. - CTSK expression did not significantly differ

1. Table 1. Clinicopathologic characteristics of the worked cases of SGCs
Clinicopathologic variables Frequency Percentage
Patient gender male 18 40
female 27 60
Tumor type Low-grade MEC 7 15.6
High-grade MEC 13 28.9
Adenoid cystic carcinoma 12 26.7
Carcinoma ex pleomorphic
adenoma 8 17.8
Acinic cell carcinoma 5 11.1
Histologic grade Low-grade carcinomas 12 26.7
High-grade carcinomas 33 73.3
Tumor site parotid salivary gland 23 51.1
Submandibular salivary gland 12 26.7
Soft and hard palate minor
salivary glands 5 11.1
Sublingual major salivary
gland 4 8.9
Retromolar mucosa 1 2.2
Tumor size T1 7 15.6
T2 12 26.7
T3 17 37.8
T4 9 20

2. Clinicopathologic variables Frequency Percentage
Status of nodal involvement positive nodal involvement 26 57.8
negative nodal involvement 19 42.2
Distant metastasis present 17 37.8
absent 28 62.2
TNM stage stage I 7 15.6
stage II 6 13.3
stage III 13 28.9
stage IV 19 42.2
Incidence of recurrence Present 17 37.8
Absent 28 62.2
Incidence of death Died 5 11.1
Alive 40 88.9
CTSK expression Negative expression 8 17.8
Weak expression 8 17.8
Moderate expression 6 13.3
Strong expression 23 51.1
Total 45 100

3.  CTSK was not detected in the normal salivary gland tissue. In SGCs, CTSK was present mainly in
carcinoma cells, but sometimes present in stromal cells.
 CTSK-positive cells at the stroma were present surrounding the invasive front. we observed that
metastatic SGC cells in lymph nodes were also positive for CTSK (Fig. 1).
 The vast majority of metastasis-free lymph nodes did not express CTSK. A higher percentage of the
worked cases had positive CTSK expressions 82.2%), and only eight of the worked cases had negative
expressions (17.8%).
 Weak expression was observed in eight cases (17.8%), six cases (13.3%) showed moderate expression
and 23 cases (51.1%) had strong CTSK expression.
Cathepsin K (CTSK) immunohistochemical expression
concerning the different clinicopathological variables

4. Fig. 1: Positive CTSK expression in the cancerous cells that reveal perineural (A), and lymphovascular
invasion (B) (×400)

5.  Regarding patient gender, tumor site, and the incidence of death, Pearson Chi-square test revealed no
statistically significant differences in CTSK expression among the different groups (P values were 0.799,
0.801, and 0.0.078 respectively).
 On the other hand, there were statistically significant differences in CTSK expression concerning the
following variables;
 histologic grade of tumor (P=0.000)
 histologic type of carcinoma (P=0.000)
 size of the tumor (P=0.000)
 status of nodal involvement (P=0.041)
 distant metastasis (P=0.009)
 TNM clinical stage (P=0.000)
 and the incidence of recurrence (P=0.009)

6. Histologic grade Cathepsin K
Negative or
Weak
expression
Cathepsin K
Moderate or
Strong
Expression
Total Pearson Chi-
Square Asymp.
Sig. (2-sided)
Low grade carcinomas
% within Histologic grade
12
100.0%
0
0.0%
12
100.0%
.000
High grade carcinomas
% within Histologic grade
4
12.1%
29
87.9%
33
100.0%
Total
% within Histologic grade
16
35.6%
29
64.4%
45
100.0%
Table 2: Cathepsin K immunohistochemical expression concerning the different histologic grades using Pearson chi-
square test