A challenging case of facial oedemas revealing a systemic peripheral T-cell lymphoma, not otherwise specified.

Diagnosis of peripheral T-cell lymphoma, not otherwise specified (PTCL- NOS) can be challenging because of heterogeneous clinical presentations. Objectives: To report a challenging rare case of facial oedemas revealing systemic PTCL-NOS with cutaneous, muscular and cerebral involvement. We report the case of a 20-year-old Polynesian patient presenting with facial oedemas and fever. Infectious and autoimmune aetiologies were ruled out by an exhaustive investigation. Positron emission tomography revealed subcutaneous hypermetabolism around the orbital and labial areas with diffuse muscular involvement. Muscle biopsy identified an atypical CD3+ T-cell lymphocytic infiltrate in favour of T-cell lymphomatous proliferation. Magnetic resonance imaging identified the cerebral location of a lymphoma. A palpebral biopsy revealed an infiltration of atypical T lymphocytes with irregular nuclei, expressing CD2, CD3, CD5, CD7, CD8, TOX, TIA1, granzyme B, and perforin. Delta TCR was expressed by 50% of atypical cells. Treatment with polychemotherapy and haplo-identical allogeneic stem cell transplantation (HSCT) led to a complete metabolic response. The mucocutaneous involvement was compatible with lupus panniculitis, but the immunological tests were negative, and the cutaneous histology was not compatible. Dermatomyositis was suspected, but myositis antibodies were negative. There was no clinical proximal muscle deficit and muscle histology was not compatible. In our case, as extracutaneous disease was present from the beginning, the diagnosis would be better classified as systemic (non-primary cutaneous) PTCL-NOS. This report emphasizes the importance of repeated biopsies and expert reviews for diagnosing and managing PTCL, which can have a highly variable and poor prognosis.