Primary Cutaneous CD4+ Small/Medium-Sized T-Cell Lymphoma With Spontaneous Regression After Biopsy.

Primary cutaneous CD4+ small/medium-sized T-cell lymphoma (PCSM-TCL) is a rare provisional entity included in the 2005 cutaneous lymphoma classification of the World Health Organization/European Organisation for Research and Treatment of Cancer (WHO/EORTC) in the group of primary cutaneous T-cell lymphomas. Our patient was a 44-year-old man with no past history of interest. He was seen for a nodular lesion that had appeared on the left nasal ala 3 weeks earlier and had grown progressively. At the time of consultation, this well-defined, indurated nodular lesion measured 2.5 cm in diameter and there were no changes in the overlying skin (Fig. 1). No other cutaneous lesions were observed and there were no palpable lymph nodes or organomegaly. An incisional biopsy revealed a dense, diffuse lymphocytic infiltrate in the dermis. The lymphocyte population was formed of small-sized lymphocytes associated with another population of medium-sized lymphocytes, both populations showing pleomorphism. No discernible germinal centers were found. Epidermotropism was minimal and there was slight infiltration of the follicular epithelium. Immunohistochemistry revealed a lymphocyte population formed predominantly of T cells that expressed CD3 and CD5. The CD4/CD8 ratio was greater than 2 (Fig. 2). Analysis of T-cell receptor rearrangement revealed a monoclonal T-cell population. Blood tests including complete blood count, routine biochemistry, and lactate dehydrogenase were normal, as was cervical-thoracic-abdominal computed tomography, excluding the involvement of other organs. Based on these findings we made a diagnosis of PCSM-TCL. Since the first follow-up visit, 10 days after the biopsy, the lesion was seen to regress and it had completely disappeared after 3 months (Fig. 3). In view of the good clinical course, we decided to maintain a wait-and-see approach with frequent follow-up visits. After a year the patient remained asymptomatic and no new lesions had appeared. PCSM-TCL is included as a provisional entity in the group of primary cutaneous T-cell lymphomas, both in the 2005 WHO/EORTC classification of cutaneous lymphomas and in the latest (2008) classification of tumors of hematopoietic and lymphoid tissue. It is a rare disease that accounts for approximately 2% to 3% of primary cutaneous lymphomas.