Background: Basal cell
carcinoma (BCC) and trichoepithelioma (TE) have some similarities clinically
and histologically. The aim of this work is to evaluate the role of Bcl-2, CD10
and CD34 in differentiation between BCC and TE. Methods: The
immunohistochemical expression of Bcl-2, CD10 and CD34 was evaluated in 20 BCCs
and 12 TEs in a retrospective study. The localization of these markers in tumor
and stromal cells was determined and comparison between BCC and TE was done.
Immunohistochemistry for Bcl-2, CD10 and CD34 was performed on sections
obtained from formalin-fixed, paraffin-embedded blocks. Bcl-2, CD10 and CD34
immunoreactivity in the stromal and/or tumor cells was determined as follows:
negative (0); 1+ (10% - 50% positive cells); and 2+ (>50% positive cells). Results:
In BCC (20 cases), the expression of Bcl-2 in stromal cells showed (0)
immunoreactivity in 8 cases (40%), (1+) immunoreactivity in 7 cases (35%), and
(2+) immunoreactivity in 5 cases (25%). Tumoral cells showed diffuse positivity
in 20 out of 20 cases (100%), (1+) immunoreactivity in 5 cases (25%) and (2+)
immunoreactivity in 15 cases (75%). On the other hand, the expression of Bcl2
in TE, 4 cases showed positive stromal cells out of 12 (33.33%), (1+)
immunoreactivity in 2 cases (16.6%) and (2+) immunoreactivity in 2 cases
(16.6%), and 8 cases showed no immunoreactivity. Tumoral cells showed
positivity in 12 out of 12 cases (100%), (1+) immunoreactivity in 5 cases
(41.6%), (2+) immunoreactivity in 7 cases (58.3%). In BCC cases, the expression
of CD10 was noted in stromal cells in 8 out of 20 cases (40%), 5 cases showed
positivity in stromal and basaloid cells and 3 cases showed positivity in
stromal cells only, and 12 cases showed no immunoreactivity (60%). Tumor cells
showed positivity in 11 cases out of 20 (55%), (1+) immunoreactivity in 6 cases
(30%), (2+) in 5 cases (25%), and 9 cases showed no immunoreactivity (45%). On
the other hand, the expression of CD10 in TE 7 cases showed positive stromal
cells out of 12 (58.33%), (1+) immunoreactivity in 5 cases (41.6%) and (2+) in
2 cases (16.6%), and 5 cases showed no immunoreactivity (41.66%). Tumor cells
showed positivity in 5 cases out of 12 (41.66%), (1+) immunoreactivity in 4
cases (33.33%) and (2+) in 1 case (8.3%), and 7 cases showed no
immunoreactivity (58.33%). In BCC cases, the expression of CD34 was noted in
stromal cells in14 cases out of 20 cases (70%), (1+) immunoreactivity in 10
cases (50%) and (2+) in 4 cases (20%), and 6 cases showed no immunoreactivity (30%).
On the other hand, the expression of CD34 in TE, 10 cases showed positive
stromal cells out of 12 (83.33%), (1+) immunoreactivity in 6 cases (50%) and
(2+) in 4 cases (33.33%), and 2 cases showed no immunoreactivity (16.6%). Tumor
cells showed no immunoreactivity for CD 34 in both BCC and trichoepithelioma,
(100%) negative tumor cells. Significant difference of tumor\stromal cells
immunoreactivity for Bcl-2 and CD34 in both BCC and TE but it was insignificant
for CD10. Conclusion: We conclude that Bcl-2 CD10, CD34 are useful markers in
the differential diagnosis of BCC versus TE.