Mesenteric Microcystic/Reticular Schwannoma: A Diagnostic Dilemma

Microcystic/reticular schwannoma is a rare variant of schwannoma with a predilection for visceral locations including the gastrointestinal tract. Due to overlapping features with other tumours, unawareness of this tumour type may lead to diagnostic pitfalls. We here report a case of microcystic/reticular schwannoma arising in the mesentery of a 25-year-old female. The tumour was incidentally discovered by ultrasonography. An operation was performed and histological examination revealed a capsulated tumour composed of spindle cells with reticular pattern set within a myxoid stroma. Differential diagnoses were Extra Gastrointestinal Stromal Tumour (EGIST) with myxoid change, microcystic/reticular schwannoma, Low-Grade Fibromyxoid Sarcoma (LGFMS) and Aggressive Angiomyxoma (AAM). Immunohistochemically, the tumour cells were positive for S-100 protein which was consistent with a peripheral nerve sheath tumour. Albeit very rare, microcystic/reticular schwannoma should be included in the differential diagnosis of mesenteric tumours. The awareness and the knowledge about this rare tumour are needed to achieve the correct diagnosis.