A 42-year-old male presented with a prolactin-producing pituitary adenoma with an atypical radiologi cal appearance. The tumor was incidentally found by magnetic resonance imaging, which demonstrat ed a cystic tumor in the enlarged and partially empty sella turcica. Computed tomography revealed the tumor was surrounded by calcification with an egg-shell appearance. The serum prolactin level was 37 ng/ml. The operative finding was a calcified shell-containing cystic tumor. Immunohistochemical

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... in ing revealed prolactin-positive cells. The combination of the unusual calcification , and enlarged and partially empty sella was considered to be a sequela of spontaneous degeneration of the tumor.