Pitfalls in Cytological Diagnosis of Extra Adrenal Paraganglioma and Pheochromocytoma: Experience From a Tertiary Care Center.

Background: Pheochromocytoma and extra-adrenal paragangliomas increasingly coming into light nowadays because of improved imaging techniques and biochemical investigations. There is sparse literature available regarding cytological findings of adrenal and extra-adrenal paragangliomas.

Material and methods: We studied 16 cytological specimens retrospectively over a period of 3 years, where subsequent histological diagnosis of phaeochromocytoma or paraganglioma was available.

Results: A total of 16 cytology specimens were studied. Nine patients had adrenal SOLs and seven patients had extra-adrenal lesions. Age range was 12 to 60 years Majority of the cytology smears were cellular (87.5%). The smears were composed of small clusters as well as dispersed plasmacytoid cells with eccentric nuclei containing salt and pepper chromatin and moderate to abundant granular cytoplasm. Large cellular clusters mimicking the Zellballen pattern was present in one case. Anisonucleosis was mild to moderate, except in three cases where marked anisonucleosis posed diagnostic challenges. The background was hemorrhagic in all cases, however, two cases in addition had necroinflammatory background. All cases lacked mitotic activity and cytoplasm was delicate with indistinct cell borders. Bare oval nuclei were a frequent finding. Nuclear grooves or cytoplasmic vacuoles were absent. In 12 out of 16 cases, the initial cytological diagnosis correlated with final histological diagnosis, with an overall diagnostic accuracy of 75%. Four misdiagnosed cases had some atypical cytological features like marked anisonucleosis, necroinflammatory background, and presence of prominent nucleoli.

Conclusion: Here we have highlighted some of the distinguishing cytological features that can help in cytological diagnosis of paragangliomas. Hemorrhagic background with plasmacytoid morphology, granular cytoplasm, naked nuclei, and absence of mitosis are useful clues.