Ruolo della microscopia elettronica e della reazione uranaffine nella diagnosi dei chemodectomi del cane

The diagnosis of neuroendocrine tumors and, specifically in this case, chemodectomas, could be a challengefor pathologists, due to the poor differentiation resulting in misleading immunohistochemical results and thelimited availability of antibodies for the characterization of neurosecretory products. Moreover, argirophilicstaining could give a faint, randomly positive or negative reaction. Therefore, TEM associated withuranaffin reaction – a cytochemical stain localizing adenine nucleotides in organelles storing biogenicamines – should be applied. In the present study, 5 chemodectomas of aortic (3/5) and carotid (2/5) bodyhave been submitted for argirophilic stains (Grimelius, Churukian Schenk), routine TEM analysis anduranaffin reaction (treatment with 0.9% NaCl for 48 hrs and 4% uranyl acetate for 48 hrs at 4°C). Uranaffinreaction was positive (electrondense granules, lack or faint staining of other cell components, exceptchromatin and ribosomes) in all cases, also those negative or poorly stained by argirophilic methods, withscarce granules or advanced autolysis. Furthermore, TEM examination revealed an high granulespleomorphism (different electrondensity and content compartimentalization), related to variable maturation,hormones and nucleotides levels and mechanisms of secretion. Finally, TEM analysis strengthened byuranaffin reaction is recommended in all doubtful chemodectomas and, generally, in all tumors withsuspected neuroendocrine differentiation.[...]