Intravascular natural killer cell lymphoma mimicking mycosis fungoides: a case report and review of the literature.

Intravascular lymphoma is a rare entity. Most cases constitute a variant of extranodal diffuse large B-cell lymphoma, and only 10% of the published cases are of T-cell or histiocytic origin. Even fewer cases of intravascular natural killer (NK) cell lymphoma have been reported. To date, only the intravascular lymphoma of B-cell linage is recognized as a distinct entity by the WHO Classification. Here, we report the clinical, morphological, immunohistochemical, and molecular findings of a 72-year-old male patient with intravascular NK-cell lymphoma of the skin who initially presented with red skin efflorescences suspicious of mycosis fungoides. A skin biopsy revealed large cell infiltrates of NK/T-cell phenotype (CD3ε, CD4, CD8, CD56, and TIA-1), which were localized strictly intravascularly and which were positive for Epstein-Barr virus nucleic acid EBER (Epstein-Barr virus-encoded small RNA). Molecular studies revealed a germline configuration for the T-cell receptor consistent with the possibility of an NK-cell origin. At the beginning, the disease appeared to be limited to the skin with no sign of bone marrow involvement or leukemic dissemination. Chemotherapy was initiated; however, the patient subsequently developed meningiosis lymphomatosa with recurrent epileptic episodes and bone marrow infiltration with pancytopenia 7 months after primary admission. Finally, the patient passed away in a septic shock.

MAGE-A3 is a frequent tumor antigen of metastasized melanoma.

MAGE-3 or MAGE-A3 is one of the best-characterized tumor antigens. Due to its tumor-restricted expression pattern and its recognition by both cytotoxic and helper T cells it constitutes a promising tumor antigen for anticancer immunotherapy, notably of malignant melanoma. Surprisingly, however, only very limited information is available on the frequency and consistency of its expression in metastatic melanoma lesions. We have now investigated the presence of MAGE-A3 mRNA in 316 tumor samples from 147 melanoma patients by RT-PCR. MAGE-A3 mRNA was detectable in 62% of metastases, and expression did not depend on the site of the metastases (skin, lymph node, and internal organs), age, sex, or duration of disease. Southern blot hybridization of the PCR product enhanced sensitivity of detection, and 26% more samples (13/50 samples tested) scored positive, indicating an even higher MAGE-A3 mRNA frequency than determined by simple ethidium bromide gel analysis. In 62 patients, we were able to investigate MAGE-A3 expression in several metastases from the same patient, and unexpectedly, both MAGE-A3-positive and MAGE-A3-negative metastases were found in 32% of these patients (20 of 62). Immunohistochemistry (using mAb 57B) demonstrated that the expression pattern was usually also heterogeneous with positively and negatively stained tumor cells within one metastasis. However, most (90%) of the metastases (47/52) gave a partially positive signal. Taken together, MAGE-A3 is a common and frequent tumor antigen in metastasized melanoma, but its expression is often heterogeneous.