Abstract
Primary cutaneous T-cell lymphomas (PTCLs) are defined as non- Hodgkin lymphomas in the skin with no evidence of extracutaneous involvement at the time of diagnosis. In the recent lymphoma classifications, PTCLs are further divided into cutaneous T-cell lymphoma (CTCL) and cutaneous B-cell lymphoma (CBCL). CTCL are a group of lymphoproliferative disorders characterized by the localization of the neoplastic T lymphocytes in the skin. CD20-positive CTCL is a rare condition that is associated with the co-expressions of CD20 and T-cell. CD20 is a marker that is commonly used in the investigation of B-cell to assist in differentiating T-cell and B-cell neoplasms. CD20-positive T-cell lymphoma is extremely rare with only fewer than 40 cases have been reported. In these cases, the skin involvement manifests as cutaneous plaques, nodules, or erythematous patches without predilection for specific locations.
We report a case of CD20-positive T-cell lymphoma in a 90-year-old woman. Diagnosis was established based on the history, physical examination, and histopathology examination supported by positive CD3 and CD20 staining on immunohistochemistry (IHC). The patient was treated with R-CHOP (Rituximab - cyclophosphamide, doxorubicin, vincristine, and prednisone) regimen and showed significant clinical improvement after 2 cycles of chemotherapy.

Key words: Cutaneous T-cell Lymphoma, CD20, CD3, R-CHOP