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The “ancient” variant of schwannomas is a rare subtype of a benign encapsulated neoplasm of nerve sheath. A review of current literature has revealed several reported sites but not in the hypopharynx. Here we report such a hypopharyngeal tumour arising in a 32 year old man, paying particular attention to the potential diagnostic difficulties.
“Ancient” Schwannomas are benign nerve origin neoplasms that may cause difficulties in the differential diagnosis with other benign or malignant tumours. Though they usually occur in head and neck region, we could not find references pertaining to the ancient variant in the hypopharyngeal region. The present case describes a 32 year old man who presented with difficulty in breathing and hoarseness of voice of 6 months duration and had no features of neurofibromatosis. The case is being presented for its rarity and aims to increase the awareness of possibility that these tumours may also exist in hypopharynx mimicking more frequent lesions.
A 32 year old man presented with a 6 month history of hoarseness of voice and difficulty in breathing. He had no features of neurofibromatosis. Indirect Laryngoscopy showed a smooth mass in the left hypopharyngeal region. No lymphadenopathy was detected. Under general anesthesia the mass was removed and sent for histology. The resected specimen was gray white to gray brown measured 4.5 × 4 × 2 cms, well encapsulated and had nodular surface. Cutsection showed gray white solid areas admixed with multiple cystic areas filled with myxoid material along with areas of hemorrhage. Microscopically proliferation of spindled shaped cells with fibrillary cytoplasm was seen with dense fibrous bands arranging the cells into nodules. In some cells marked nuclear hyperchromatism and atypia were seen. Mitoses were not present. Within the lesion, cellular areas were interspersed with looser myxoid and cystic areas. Blood vessels with thickened hyalinised walls were noted (Fig. 1). Staining for S 100 protein was positive in the tumour cells (Fig. 2). The histological features are that of an ancient schwannoma.
A Schwannoma is a benign encapsulated neoplasm derived from schwann cells of nerve sheath. The exact incidence of schwannomas is unknown, but they are rare. Schwannomas are found in all age groups but are more common in the first four decades and affect both sexes equally. They may occur in association with neurofibromatosis or arise sporadically. The microscopic appearance of schwannoma is distinctive , with two recognisable patterns. Antoni A areas are composed of compact spindle cells often arranged in palisades or in an organoid arrangement (verocay bodies). Antoni B areas consist of tumour cells suspended in a myxomatous matrix that may appear microcystic. Several variants of schwannomas based on appearances have been observed, including cellular, glandular, epithelioid and ancient types and exhibit benign progression. Cellular schwannomas are almost exclusively composed of antoni A areas but lack verocay bodies. The epithelioid and glandular variants compose of epithelioid areas and glandular component respectively to acquire their descriptive names.
Ancient schwannomas show bizarre hyperchromatic nuclei without mitoses. To the inexperienced these features can lead to an erroneous diagnosis of malignancy, although the very low mitotic activity should allow these tumours to be distinguished from malignant nerve sheath tumours.
A literature review showed that ancient schwannomas are rare, most cases occur in the head and neck region . Other less common sites include the extremities, mediastinum, thorax , retroperitoneum , pancreas , pelvis  and scrotum . We could not find references pertaining to ancient variant in the hypopharyngeal region.
Ancient schwannomas involving hypopharynx pose a difficult diagnostic challenge to ENT surgeons. Radiological findings are often non-specific . Ultrasonography can differentiate between solid and cystic tumours. CT scan can be helpful in determining the size, location, local involvement and distant spread. Magnetic resonance imaging (MRI) provides similar useful information as CT but yields better visualization of the tumour . Fine needle aspiration cytology is difficult in this area, if done is not often helpful because the tissue architectural information required is not obtainable from cytological specimen. The only gold standard diagnostic investigation is histology of either biopsy or excised specimen.
This case is reported for its rarity and to pay attention to diagnostic difficulties and to increase the awareness of the possibility that these tumours may also exist in the hypopharynx mimicking more frequent lesions.