Unusual variants of adrenal pseudocysts with intracystic fat, myelolipomatous metaplasia, and metastatic carcinoma.

Five previously unreported cases of adrenal pseudocysts are described that demonstrate a wider range of histologic appearances than has been previously recognized in these lesions. One pseudocyst removed from an asymptomatic 59-year-old female contained intracystic nests of cytologically malignant cells of unknown origin. Workup revealed a left breast mass, which on biopsy showed an infiltrating ductal carcinoma with neoplastic cells that were cytologically similar to those found within the cyst contents. Four other pseudocysts are described with variable numbers of intracystic vascular structures and benign adrenal cortical cells. In addition, intracystic mature adipose tissue was observed in all four cases, with myelolipomatous metaplasia found in one. Awareness of the wide histologic variability of these lesions should improve diagnostic accuracy and allow distinction from adrenocortical neoplasia and myelolipoma.