Gangliocytic Paraganglioma: a Diagnostic Pitfall of Rare Neuroendocrine Tumor

Abstract

Dear Editor:We wish to comment on the gangliocytic paraganglioma research. Since hypoxia-inducible factor 2α gain-of-function mutations were detected in gangliocytic paraganglioma (GP) [1], as well as paraganglioma and somatostatinoma [2], this neuroendocrine tumor may be relative tumors of paraganglioma and/or somatostatinoma. In fact, there are similar morphological and immunohistochemical features between paraganglioma and GP, except for the existence of ganglion-like cell in GP [3]. In addition, GP often shows positive immunoreactivity for somatostatin [3,4]. To differentiate GP from paraganglioma, pathologists should consider the primary tumor site and the existence of ganglion-like cell (paraganglioma lacks ganglion-like cells, and it is very rare in the duodenum) [4]. On the other hand, morphological differences between GP and somatostatinoma make differentiation easy, and immunoreactivity for progesterone receptor and pancreatic polypeptide which is discussed below may be useful to differentiate them [5].Meanwhile, the most important differential diagnosis of GP is neuroendocrine tumor (NET) G1. Indeed, the patients with GP may have a better prognosis than the patients with NET G1, but GP has often been misdiagnosed as NET G1 owing to its morphological similar findings and low proliferative activity [4,5]. Thus, we would like to emphasize the usefulness of immunohistochemical examinations using progesterone receptor and pancreatic polypeptide to differentiate them. Namely, typical epithelioid cell (a major component of GP)shows positive immunoreactivity with them, whereas tumor cell of NET G1 was negative for both immunohistochemistries [4,5]. We believe that these findings may be useful to differentiate GP from NET G1, including small specimen obtained from biopsy.

Biliary Neuroendocrine Neoplasms: Clinical Profiles, Management, and Analysis of Prognostic Factors

“…And it has also been reported that GP accounts for ~40% of duodenal NETs (15). GPs show better prognosis compared with G1 NETs (16), thus it is important to differentiate GPs from NETs. Morphologically, GP comprises three characteristic cell types: epithelioid cells, spindle-shaped cells and ganglion-like cells.…”

Diagnosis, Pathological Findings, and Clinical Management of Gangliocytic Paraganglioma: A Systematic Review

“…Thus, pathologists should consider the primary lesion and the presence of ganglion-like cells. For instance, ganglion-like cells are absent from paraganglioma, which rarely arises from the duodenum ( 46 ). Although NET G1 is the most important differential diagnosis, GP is often misdiagnosed as NET G1 ( 8 ).…”

Gangliocytic paraganglioma: An overview and future perspective

“…Thus, it is important to distinguish between GP and NET G1. However, morphological and immunohistochemical similarities between GP and NET G1 may lead to misdiagnosis[8,9]. Thus, oncologists, clinicians, and pathologists should be aware of the concept of GP because our previous study suggests that GP accounts for a consistent proportion of NETs arising from the duodenum[10].…”