Biomedical Research

A Japanese man in his mid-60s reported having a subcutaneous mass for a period of 8 months, after which it gradually enlarged in size and was surgically extirpated. The resected tumor was 10 × 8 mm in size, and the cut surface was smooth, solid, and whitish. Histological analysis revealed the presence of medium to large lymphoid cells that had proliferated to form a solid mass. The diffuse proliferating cells stained positive for CD20, CD79a, and CD5, but were negative for CD3, CD30, and CD10, and the MIB-1 index was very high. On the basis of these findings, the tumor was diagnosed as cutaneous CD5+ diffuse large B cell lymphoma. Interestingly, detailed analysis revealed elastophagocytosis, with scattered, fragmented elastic fibers engulfed by macrophages that were intermixed with tumor cells. These macrophages were mostly multinucleated giant cells, apparently forming part of a foreign body-type reaction. Elastic fiber staining clearly revealed positively stained fragmented fibers in the cytoplasm of the macrophages, which were densely positive for CD68, in sharp contrast to the CD68-negative tumor cells. The final diagnosis was cutaneous CD5+ diffuse large B cell lymphoma exhibiting unusual elastophagocytosis. The patient’s clinical course was good, and the tumor disappeared completely after 3 cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) therapy with radiation.

Author(s): Yuji Ohtsuki, Yuki Matsuka, Wakana Tanihata, Masako Izumimoto, Yuhei Okada, Gang-Hong Lee, Mutsuo Furihata, Katsuyoshi Takata, Tadashi Yoshino
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