Primary cutaneous gamma/delta T-cell lymphoma in Taiwan: A series of six cases with frequent solitary presentation and relatively indolent behavior

Background: Primary cutaneous gamma/delta T-cell lymphoma (PCDG-TCL) is aggressive, frequently presenting as multiple plaques, tumors, and/or subcutaneous nodules. Methods: In this study, we conducted a retrospective study in a tertiary center in Taiwan to characterize this rare tumor. Results: We identified six patients. Five presented with a solitary lesion, including two with clinical impression of epidermal inclusion cyst or lipoma. Two of four evaluable cases exhibited epidermotropism, with one mimicking Pautrier microabscess. The neoplastic cells were pleomorphic and mostly medium- to large-sized. In all cases, the neoplastic cells expressed T-cell receptor (TCR)-γ and/or TCR-δ, with four co-expressing βF1. Two of these βF1+ cases co-expressed TCR-γ but not TCR-δ (two different clones). All were negative for Epstein–Barr virus (EBV), low stage, and treated with radiotherapy alone or combined chemotherapy and radiotherapy. In two patients, lymphoma relapsed in 3 and 7 months, respectively, and one patient died of the disease in 7 months. Four other patients were free of disease for 6 to 126 months. Conclusion: PCGD-TCL cases in Taiwan are more commonly solitary, frequently with indolent courses. The two currently available TCR-δ clones alone might be insufficient to detect all tumors.