Schwannoma masquerading as a thyroid nodule: A diagnostic delimma.

We present a case of a 70 years old female presenting with a long-standing neck swelling with a recent increase in size and new onset pain. It was initially diagnosed and operated on as a cold nodule of thyroid as her thyroid scan showed left cold nodule and FNAC was inconclusive. However, a final diagnosis of schwannoma with Antoni A structures was made on histopathological attributes. Schwannomas are benign peripheral nerve tumors which grow slowly on parent nerves. The mainstay of treatment is surgical excision. To avoid unnecessary or inappropriate interventions, thorough pre-operative assessment is required in case of thyroid or non-thyroidal lesions as most are hypoechogenic on ultrasonography and fine needle aspiration has low diagnostic yield. The key pre-operative investigations are ultrasound and ultrasound guided cytology and immunohistochemical staining (for example S-100, calcitonin, CEA, thyroglobulin, TTF-1, melan-A, HMB45 and Ki-67). MRI is also a good diagnostic tool in neck swellings where diagnosis is uncertain.