[Ki-1-positive anaplastic large-cell lymphoma with mediastinal involvement]

A 30-year-old woman was admitted to our hospital because of an abnormal mass shadow in the right side of the mediastinum on a a chest X-ray film. The chest X-ray film and computed tomogram revealed a mass approximately 4.8 cm in diameter in the right side of the mediastinum. The mass had invaded the right supraclavicular fossa. Lymph-node biopsy was done. Microscopical examination of an HE-stained specimen of a supraclavicular lymph nodes showed prediferation of large atypical lymphocytes. These atypical lymphocytes were stained immunohistochemically with anti-Ki-1 antibody. No T cell or B cell markers were found on these cells. No other tumors were detected by radiological examination. Therefore, our diagnosis was anaplastic large-cell lymphoma, which is identical to Ki-1 lymphoma of the mediastinum.