Granular cell tumour of the oesophagus mimicking a gastrointestinal stromal tumour on frozen section

Plexiform fibromyxoma: Review of rare mesenchymal gastric neoplasm and its differential diagnosis

Plexiform fibromyxoma (PF) is a very rare mesenchymal neoplasm of the stomach that was first described in 2007 and was officially recognized as a subtype of gastric mesenchymal neoplasm by World Health Organization (WHO) in 2010. Histologically, PF is characterized by a plexiform growth of bland spindle to ovoid cells embedded in a myxoid stroma that is rich in small vessels. The lesion is usually paucicellular. While mucosal and vascular invasion have been documented, no metastasis or malignant transformation has been reported. Its pathogenesis is largely unknown and defining molecular alterations are not currently available. There are other mesenchymal tumors arising in the gastrointestinal tract that need to be differentiated from PF given their differing biologic behaviors and malignant potential. Histologic mimics with spindle cells include gastrointestinal stromal tumor, smooth muscle tumor, and nerve sheath tumor. Histologic mimics with myxoid stroma include myxoma and aggressive angiomyxoma. Molecular alterations that have been described in a subset of PF may be seen in gastroblastoma and malignant epithelioid tumor with glioma-associated oncogene homologue 1 (GLI1) rearrangement. The recent increase in publications on PF reflects growing recognition of this entity with expansion of clinical and pathologic findings in these cases. Herein we provide a review of PF in comparison to other mesenchymal tumors with histologic and molecular resemblance to raise the awareness of this enigmatic neoplasm. Also, we highlight the challenges pathologists face when the sample is small, or such rare entity is encountered intraoperatively.

Esophageal granular cell tumor: Clinical, endoscopic and histological features of 19 cases

Esophageal granular cell tumors (GCTs) are rare and often misdiagnosed. To demonstrate their clinicopathological features, the present study reports 19 cases and reviews the literature. There were 11 female and eight male esophageal GCT patients with a median age of 42.0 years. All the tumors were solitary. The majority of patient indications for endoscopy (89.5%) were non-specific and endoscopic therapy was performed in 17 cases with a relapse in one case after a 12-month follow-up. The endoscopic appearance of esophageal GCT was variable and the majority of tumors (80.0%) were located in the middle and lower esophageal segments. The size of the tumors ranged from 0.4 to 2 cm in diameter and the surface was white-gray, pink or yellow. Nine patients underwent an endoscopic ultrasound exam, eight of which demonstrated hypoechoic echostructures with a smooth margin and intracavity growth features. One case was derived from the muscularis propria layer with an irregular margin and intra- and extra-cavity growth features. The histological features could mimic other tumors and immunohistochemical stains are usually positive for S-100, periodic acid-Schiff, neuron-specific enolase and nestin. Three cases indicated pleomorphism and Ki-67 was locally positive. Esophageal GCTs are rare and endoscopic ultrasound features are variable. Immunohistochemical staining may aid in the diagnosis.

Peripheral nerve sheath tumors of the gastrointestinal tract: a multicenter study of 58 patients including NF1-associated gastric schwannoma and unusual morphologic variants

The frequency and morphological spectrum of gastrointestinal peripheral nerve sheath tumors (PNSTs) from consecutive case material has not been studied in the c-KIT era. We reviewed all mesenchymal gastrointestinal (GI) lesions at our departments according to current diagnostic criteria. PNSTs formed the third commonest group of mesenchymal GI tumors with a lower frequency (< or =5%) compared to gastrointestinal stromal tumors (GISTs; approximately 50%) and smooth muscle neoplasms ( approximately 30%). Granular cell tumors (GCTs; n = 31) and schwannomas (n = 22) were the most common types of PNSTs encountered. Rare tumors included neurofibromatosis 1 (NF1)-associated PNSTs (n = 5) and gastric perineurioma (n = 1). Thirteen schwannomas (including also some recent cases) were initially diagnosed as GIST, leiomyoma, or neurofibroma. Unusual histological variants included sigmoid GCT with prominent lipomatous component (n = 1), reticular-microcystic schwannoma of small (n = 1) and large (n = 1) bowel, NF1-associated gastric schwannoma (the first case to date), and psammomatous melanotic colonic schwannoma unrelated to Carney complex (n = 1). PNSTs coexisted with GIST in four patients (three had definite NF1). In conclusion, PNSTs of the GI tract are rare uniformly benign neoplasms that may show schwannian, perineurial, fibroblastic, or mixed differentiation. Most of them (92%) occurred sporadically unassociated with NF1 or NF2. Gastrointestinal PNSTs are still underrecognized by general pathologists. Awareness of their diverse morphology will help to avoid confusing them with smooth muscle neoplasms and GIST that they may closely mimic.