Fine needle aspiration cytology of retroperitoneal paraganglioma with lipofuscin pigmentation.

The cytologic features observed in fine needle aspiration smears and cell blocks from a retroperitoneal paraganglioma are described. The aspirate contained clusters of uniform cells of medium size, with ill-defined borders, round nuclei and evenly dispersed chromatin. An unusual feature was the presence of cytoplasmic pigment, which proved to be lipofuscin by histochemical staining and electron microscopy. The histologic and ultrastructural findings, as well as the results of histochemical and immunodiagnostic staining, are also presented.