Parotid gland ancient schwannoma is an extremely rare entity, with only 6 cases reported to date. Ancient schwannoma present degenerative alteration, including cystic changes, hyalinizing stroma, hemorrhages, infiltration of macrophages, and cellular atypia with hyperchromatic nuclei. These factors have the potential to mimic malignant tumors, resulting in an overestimation of diagnosis and subsequent inappropriate management. In the present case, we report a case of parotid gland ancient schwannoma, which developed relatively fast degenerative alteration without a large-sized mass. We reviewed all the cases of parotid ancient schwannoma, and suggest that the character of parotid gland tissue can deceive the change of tumor growth size. We also suspect that pre-surgical manipulation, such as FNAB or CNB, can cause degenerative changes in a relative short period. It is important to consider reactive degenerative alteration of schwannoma, and not to misinterpret as a malignant entities, notably when needle biopsy history is present.

Schwannoma, benign neoplasia derived from schwann cell, is rare tumor, and prevalent in tongue, palate, floor of mouth and buccal mucosa. Thirty-six-year-old male with asymptomatic protrusion of mandible angle was evaluated. We surgically removed the mass and histological examination gave the diagnosis of ancient schwannoma. We report a case of ancient schwannoma in masseter muscle and review of literature.

Immunohistochemical localization of vimentin, glial fibrillary acidic protein (GFAP), myelin basic protein (MBP), neuron-specific enolase (NSE) were performed to confirm the canine schwannoma diagnosed histologically. Biopsy samples from skin masses occurred on a 6 year old female dog and a 13 year old female dog were used for immunohistochemical analysis. Histologically, the tumor tissues showed the characteristics of schwannoma mainly composed of predominantly fusiform or spindle cells. The cells are arranged in small interwoven bundles with intervening fibrous and mucinous stroma that imitate a herringbone pattern. The cell nuclei have an elongated, wavy, buckled appearnce and closely bunched together. In high magnification, mitotic figure, nuclear hyperchromatism, pleomorphism and poorly defined cytoplasms were noted. the vimentin was highly expressed in the cytoplasm of all neoplastic cells. Positive reactions against NSE and GFAP, widely used to suggest a neural origin of cell types, are observed in cytoplasms of tumor cells. These results can be used as a reference data for definitive diagnosis of canine schwannoma.

Plexiform schwannoma is a rare benign tumor originated from Schwann cell with low probabilities of becoming malignant. While it has a multi-nodular character compared to the original form, its nature can be confirmed by immunohistochemical studies such as S-100 protein stain. It is rare in the nasal cavity and therefore not many cases were reported in Korea. The authors present a case of plexiform schwannoma on the nasal vestibule with a size of 2 cm.

Cases of schwannoma of the gastrointestinal tract are rare; most of these tumors are found in the stomach and the small intestine. Cases of cecal schwannoma are extremely rare. Here, we report on a case of cecal schwannoma confirmed pathologically after laparoscopic resection.