Primary Cutaneous Clonal CD8+ T-Cell Lymphoproliferative Disorder Associated With Immunodeficiency due to RAG1 Mutation.

The development of T-cell lymphomas, granulomatous reactions, and autoimmunity has been observed in immunodeficiency due to milder forms of recombination activating gene (RAG) deficiency. A few cases of cutaneous clonal papulonodular CD8 lymphocytic infiltrates and cutaneous CD8 granulomatous T-cell lymphoma have been described in association with common variable immunodeficiency, and with X-linked agammaglobulinemia. We describe a 15-year-old girl with several autoimmune disorders and recurrent infections that presented with several nodules on her cheek. Histopathological studies demonstrate histological, immunohistochemical, and molecular findings compatible with a primary cutaneous clonal CD8 T-cell lymphoproliferative disorder. Vacuolar interface changes were also seen in the involved skin, reminiscent of cutaneous lupus erythematosus. Molecular genetic analysis revealed a germline novel homozygous missense mutation in RAG1 (T1003>C). The parents were heterozygous carriers. The facial cutaneous lesions recurred despite local radiation therapy. Because of recurrent life-threatening systemic infections, allogeneic bone marrow transplantation was performed. The pathogenesis of this primary cutaneous clonal CD8 T-cell lymphoproliferative disorder may have been related to a chronic stimulation of autoreactive T cells in the involved skin paired with reduced RAG1 activity.