Importance: In the recent World Health Organization-European Organisation for Research and Treatment of Cancer classification, primary cutaneous CD4+ small- to medium-sized pleomorphic T-cell lymphoma is listed as a provisional entity that is histopathologically characterized by pleomorphic CD3+/CD4+/CD8-/CD30- T lymphocytes. Clinically, it is characterized by solitary tumors mostly affecting the head and neck area and by an indolent clinical course with an estimated 5-year survival of about 60% to 80%. Currently, therapeutic options include topical or systemic treatment with glucocorticoids, local excision of solitary lesions, radiotherapy, and chemotherapy (e.g., cyclophosphamide) in cases of aggressive clinical behavior or systemic disease.
Observations: We present the case of a 21-year-old female patient with a 5-year history of a solitary, slowly growing tumor of the right cheek. Histopathologic findings revealed a primary cutaneous CD4+ small- to medium-sized pleomorphic T-cell lymphoma with an admixture of numerous CD20+ B cells representing almost half of the infiltrate. In this patient we achieved a temporary (13 months) complete remission of the lymphoma by oral treatment with doxycycline monohydrate, 200 mg per day.
Conclusions and relevance: Doxycycline is a relatively nontoxic and well-tolerated oral agent and should be considered as a therapeutic option in primary cutaneous CD4+ small- to medium-sized pleomorphic T-cell lymphoma, especially in cases with a high percentage of B lymphocytes and no signs of systemic disease.