Cytological Diagnosis of Duodenal Gangliocytic Paraganglioma on Ultrasound-Guided Fine Needle Aspirate: A Case Report with Review of the Literature

Abstract

Duodenal gangliocytic paraganglioma (DGP) is a rare neoplasm usually found in the second portion of the duodenum and comprised of epithelioid neuroendocrine cells, Schwann cell-like spindle cells, and ganglion cells. We report a case of a 58-year-old male with a duodenal mass discovered incidentally during a staging PET scan for an oropharyngeal carcinoma. An ultrasound-guided fine needle aspirate (FNA) of the lesion revealed fascicles of spindle cells and sparse epithelioid cells with mild cytological atypia. Cell-block prepared from this specimen showed fragments of tightly packed clusters of spindle cells positive for S-100 and Sox 10. A diagnosis of a spindle cell neoplasm, favoring a schwannoma, was rendered. Subsequent surgical resection of this 2.8 cm submucosal mass showed predominantly spindled Schwann-like cells, interspersed epithelioid cells, rare ganglion cells, and an immunohistochemical profile that confirmed the diagnosis of DGP. On retrospective review of the prior aspirate, rare Neurofilament protein (NFP) positive ganglion cells were also identified and thus concluded to be consistent with DGP. Although two case reports of DGP, both with regional metastatic lymph nodal disease, have been previously described in the English language literature, this is the first case report describing the cytological features of a DGP without evidence of lymph node metastasis. In conclusion, in the evaluation of submucosal duodenal lesions by US-guided FNA, the possibility of a DGP should be included in the differential diagnosis when two or all three cell elements required for this diagnosis are identified and their phenotype is confirmed by immunohistochemical markers. spindle cells, and ganglion-like cells. Although most commonly found in the second part of the duodenum, with a predilection for the periampullary region, rare cases with involvement of the jejunum, pylorus, esophagus, pancreas, appendix, and lung have also been reported in the literature [1]. DGP is generally considered a benign lesion, however, metastasis to regional lymph nodes or rarely to other organs, including one case with bone metastasis and two with liver metastasis, have also been reported in approximately 5-7% of cases [28]. Most cases are diagnosed on surgical resection, and to our knowledge, only two case reports describing the cytological features of DGP have been reported in the English language literature [6,8]. Interestingly, both cases were associated with metastasis to locoregional lymph nodes. Herein, we present the cytological features of a new case of DGP presenting as a solitary submucosal mass without evidence of lymph node metastasis. In addition, we will discuss the differential diagnosis with other submucosal duodenal lesions, and the limitations that sometimes may preclude its diagnosis on US-guided FNA.