Use of formaldehyde-induced fluorescence for cytological diagnosis of pheochromocytoma

Eleven cases with pheochromocytoma were cytologically investigated on touch preparations using formaldehyde-induced fluorescence method (FIF) in addition to the usual Papanicolaou's stain (PAP) and May-Grünwald Giemsa stain (MGG). The specific catecholamine fluorescence was successfully observed in the cytoplasm of tumor cells and also in the background. Application of FIF for touch preparation is simple in technique and may greatly contribute for confirmation of the diagnosis of pheochromocytoma. MGG stained the cytoplasm composed of two-tone colors: eosinophilic granular in the perikarya and basophilic granular around nucleus. Electronmicroscopically, they were consistent with catecholamine granules and abundant rough endoplasmic reticulums, respectively. Although, it is fairly difficult to determine whether tumor cells are other malignant tumors or not by using PAP, small N/C ratio might be a useful index for pheochromocytoma. Combination of FIF, MGG, and PAP makes it easy to confirm the diagnosis of pheochromocytoma.