Reticular and microcystic schwannoma of the parotid gland

Abstract

Background Microcystic/reticular variant of schwannoma is a rare, distinctive variant of schwannoma with predilection for visceral sites. Fewer than 20 cases are described in the literature and involvement of head and neck has not previously been reported. Microcystic/reticular variant of schwannoma demonstrates similar biological behaviour to usual schwannoma and should be distinguished from parotid gland tumours that may recur aggressively if incompletely excised. Aim To present a case of microcystic/reticular variant of schwannoma in the parotid gland with literature review and discuss pertinent differential diagnoses. Case report A 59-year-old female presented with a preauricular swelling. FNA showed cytologically bland spindle shaped cells amidst myxoid stroma. At operation, the tumour was found to be closely associated with facial nerve and was resected with nerve preservation. Histopathological examination showed a well circumscribed, unencapsulated lesion composed of slender, spindle shaped cells with intracytoplasmic vacuoles amidst myxoid stroma. Areas with accordion-like linear cellular arrays, reticular pattern and microcysts were present. Features of typical schwannoma, atypia, mitoses, or necrosis were absent. Diffuse immunor-eactivity with S100 was noted. Immunohistochemistry helped exclude differential diagnoses like myoepithelioma, pleomorphic adenoma, perineuroma, parachordoma, and epithelioid haemangio-endothelioma. Conclusion We present a case of microcystic/reticular variant of schwannoma in the head and neck, to our knowledge the first report of this entity in this location.