Document Type: Original Article

Authors

1 Molecular Dermatology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran

2 Pathology Department, Shiraz University of Medical Sciences, Shiraz, Iran

Abstract

Background: The lack of a specific marker to differentiate malignant from reactive
T-cells makes a definite diagnosis difficult in patients suspected of having mycosis
fungoides. This study has evaluated value of thymocyte selection-associated high
mobility group box factor expression in the differentiation of early mycosis fungoides
from a benign inflammatory dermatosis.
Methods:We selected 22 mycosis fungoides cases, 18 cases suspicious for mycosis
fungoides, and 12 cases of eczematous dermatitis from patients who attended
Dermatology Clinic, Shiraz University of Medical Sciences (2008-2015). The obtained
skin biopsies were immunostained for thymocyte selection-associated high mobility
group box factor antigen in addition to pan T cell markers. The slides were evaluated
for the percentage of tumor cells and intensity of immunoreactivity.
Results: From 22 cases of mycosis fungoides, 40.9% showed massive infiltration
of thymocyte selection-associated high mobility group box factor-positive lymphocytes
(>30%) with high (3+) intensity in the epidermis; there was no case negative for
thymocyte selection-associated high mobility group box factor expression. Only one
eczematous dermatitis case had expression of thymocyte selection-associated high
mobility group box factor-positive lymphocytes (>30%) with high intensity and 4 cases
were negative for thymocyte selection-associated high mobility group box factor
expression. The frequency of thymocyte selection-associated high mobility group
box factor expressing lymphocytes was higher in biopsies from mycosis fungoides
compared to eczematous dermatitis (P<0.05). CD7- cases expressed more thymocyte
selection-associated high mobility group box factor-positive lymphocytes in the dermis
and epidermis, which were significantly correlated (P=0.013).
Conclusion: Thymocyte selection-associated high mobility group box factor, as a
positive marker, in combination with pan T cell markers (especially CD7-) can be useful
to detect mycosis fungoides malignant lymphoid cells.

Keywords