UNUSUAL INTRACYTOPLASMIC INCLUSIONS IN METASTATIC CARCINOMA - DISCUSSION OF THEIR POSSIBLE SIGNIFICANCE

Unusual filamentous inclusion bodies in the cytoplasm of metastatic tu mor cells are described. Their presence (intermingled with zymogen gra nules) seems rather restricted to cells of primary or metastatic acina r cell carcinoma of the pancreas, acinic carcinoma of salivary gland ( parotid gland) and Paneth cells (neoplastic or in zinc deficiency stat e). For the time being, the real nature of these inclusions (deranged zymogen granules?) is unclear. This case also emphasizes the value of electron microscopy in solving the problem of the occult primary tumor and avoiding the misdiagnosis of an endocrine tumor (e.g. islet cell tumor or carcinoid), or a duct cell tumor with eosinophilic granular c ytoplasm or in recognizing the foci of acinar cells in a mixed variant of carcinoma of the pancreas.