Microcystic/reticular schwannoma: a distinct variant with predilection for visceral locations.
ABSTRACT Schwannomas are benign, generally nonrecurring tumors most frequently arising in the subcutaneous tissue of adults with no sex predilection. Herein we report 10 cases of a distinctive morphologic variant of schwannoma with predominantly microcystic-reticular morphology and characterize the clinicopathologic spectrum. The age at presentation ranged from 11 to 93 years (median age 63 y). The tumor size ranged from 0.4 to 23 cm (median size 4.3 cm). Five tumors arose in the gastrointestinal tract, most often in the submucosa. Two cases arose in subcutaneous tissue and 1 case each in the upper respiratory tract, the adrenal gland, and deep soft tissue. None of the patients had features of neurofibromatosis type 1 or type 2 (NF1, NF2). Histologically 8 tumors were circumscribed but unencapsulated and 2 cases located in the subcutaneous fat were circumscribed and encapsulated. At visceral locations, focally pushing margins and microscopic foci of infiltration into surrounding parenchyma were seen. All cases showed a striking microcystic and reticular lesional growth pattern with anastomosing and intersecting strands of spindle cells with eosinophilic cytoplasm distributed around islands of myxoid or collagenous/hyalinized stroma. The nuclei were round, oval, and tapered and showed inconspicuous nucleoli. Three cases had smaller areas resembling conventional schwannoma. Mitotic activity did not exceed more than 3 mitoses/50 high-power fields (HPF) (median 1/30 HPF). Pleomorphism and necrosis were absent. All tumors showed strong nuclear and cytoplasmic positivity for S-100 and variably strong glial fibrillary acidic protein staining. A surrounding tumor capsule was highlighted with epithelial membrane antigen in 2 out of 10 cases. Smooth muscle actin, Desmin, Pan-CK, AE/AE3, Cam5.2, and p-63 were negative in all cases evaluated. Neurofilament protein highlighted axons in one out of 7 cases investigated. CD117 showed weak focal positivity in 1 out of 4 cases. Follow-up data were available in 7 cases (median duration 15 mo). None has recurred to date. Microcystic schwannoma represents a distinctive morphologic variant of schwannoma with predilection for visceral locations. Recognition of this distinct entity is essential to avoid confusion with malignant tumors, especially in the gastrointestinal and upper respiratory tracts.
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ABSTRACT: Background Schwannoma is a common, benign, peripheral nerve sheath tumor. Fine-needle aspiration (FNA) has been very useful for diagnosing classic Schwannoma. Recently, a new morphological variant, the so-called microcystic/reticular Schwannoma, has been recognized. Although histological features of microcystic/reticular Schwannoma have been described, there are no available reports on its FNA cytological appearance. Case Report A 28-year-old male presented with right arm and finger tingling and numbness. Physical examination found a right lower neck mass. He underwent FNA, followed by needle core biopsy. A diagnosis of microcystic/reticular schwannoma was made. In this case report, we focused on the FNA diagnostic features, thoroughly searched the literature, and discussed relevant information for differential diagnosis. Conclusions Unlike classic Schwannoma, microcystic/reticular variant has unique cytological features which can mimic those of several morphologically similar mass lesions, making the FNA interpretation more challenging. Cytopathologists should be aware of this new variant of Schwannoma when evaluating FNA cytology of mass lesions showing low-grade, paucicellular, and myxoid features.
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ABSTRACT: Neuroblastoma-like schwannoma is a rare variant of benign nerve sheath neoplasia, which is histologically characterized by small round neoplastic Schwann cells radially arranged around collagenous cores with a configuration of rosette-like structures. We report the first documented case of neuroblastoma-like schwannoma of the oral cavity in a 26-year-old male patient who presented with swelling in the lower labial mucosa.Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 06/2014; DOI:10.1016/j.oooo.2014.05.023 · 1.50 Impact Factor
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ABSTRACT: Microcystic/reticular schwannoma is a recently described, rare, distinctive histological variant of schwannoma with a predilection for the gastrointestinal tract (GIT). The authors experienced the first case of a microcystic/reticular schwannoma occurring in the esophagus. A 39-year-old male presented for an obstructive sensation during swallowing of several months duration. Endoscopy revealed a bulging mass with intact mucosa at 30 cm from incisors in the esophagus. The mass was excised and gross examination showed it was a well circumscribed, unencapsulated nodule, measuring 3.5×3.2×1.2 cm. On microscopic examination, the tumor showed a vague multinodular appearance with a pushing border and tumor cells arranged in a microcystic and reticular growth pattern with anastomosing and intersecting strands of spindle cells in a myxoid or collagenous/hyalinized stroma. Tumor cells showed diffuse nuclear and cytoplasmic positivity for S100. The authors report the first case of microcystic/reticular schwannoma of the esophagus. Microcystic/reticular schwannoma is a distinctive histological variant of schwannoma with a benign clinical course. However, its histological findings are non-specific and may cause diagnostic difficulties. Awareness of this uncommon neoplasm with distinct histologic features is essential to prevent misdiagnosis.BMC Gastroenterology 12/2014; 14(1):193. DOI:10.1186/s12876-014-0193-y · 2.11 Impact Factor