Pleural mesothelioma presenting as an axillary lymph node metastasis with anemone cell appearance.

A case of epithelial mesothelioma presenting as an axillary metastasis of unknown origin with anemone cells in a 33-year-old patient with pleural effusion is reported. The differential diagnosis included tumors that can be composed of cells with anemone shape (malignant lymphoma, leukemia, malignant melanoma, carcinoma, and mesothelioma). Tumor cells in the present case were positive for cytokeratins (Cam 5.2 and AE1/3) as well as vimentin antibodies and were consistently negative for carcinoembryonic antigen, Leu-M1, leukocyte common antigen, pan-B-cell and pan-T-cell antigen, Ber-H2, S-100 protein, HMB-45, and epithelial membrane antigen antibodies. On electron microscopy, the most remarkable features were the presence of abundant, long, slender microvilli, the lack of well-developed intercellular junctions, and only occasional tight junctions in some of the tumor cells. A pleural needle biopsy confirmed the pleural origin of the proliferation. The patient refused treatment and died 3 years after diagnosis.