[Extranodal NK/T-cell lymphoma, nasal-type, revealed by cutaneous breast involvement]

Extranodal NK/T-cell lymphoma (ENKTL) is a rare form of non-Hodgkin's lymphoma and carries a poor prognosis. Depending on the primary sites of anatomical involvement, it is subcategorized into nasal or extra-nasal ENKTL. Cutaneous involvement is the second localization reported for these lymphomas.

A woman was admitted for erythematous infiltrative patches on the breasts having an ulcerative course. Cutaneous histopathology showed a dense, diffuse infiltrate of atypical lymphocytes. Immunohistochemistry revealed expression of specific markers for NK-cells and of cytotoxic molecules (TIA-1, granzyme B and perforin), lack of expression of T-cell markers (except positivity of cytoplasmic CD3 and CD2), and the presence of EBV-DNA in lymphoma cells. Positron emission tomography-computed tomography revealed sub- and supra-diaphragmatic multi-organ involvement (kidneys, breasts, stomach, duodenum, lungs, pleural cavity, uterus, bones). No bone marrow infiltration was noted. PCR (polymerase chain reaction) showed high circulating levels of EBV-DNA in peripheral blood. A systemic nasal-type ENKTL was diagnosed. A chemotherapy regimen including high-dose methotrexate, oxaliplatin, gemcitabine, L-asparaginase and dexamethasone was started. Despite good initial therapeutic response, the outcome was rapidly fatal with bone marrow involvement and multi-organ failure.

Major cutaneous manifestations of ENKTL comprise erythematous infiltrative patches mimicking panniculitis or cellulitis and evolving towards ulceration or necrosis. Subcutaneous nodules may also be noted. Late diagnosis at an advanced stage accounts for the poorer prognosis in extra-nasal ENKTL. In the advanced stages, treatment is based on a chemotherapy regimen including L-asparaginase, possibly followed by autologous or allogeneic hematopoietic stem cell transplantation.