Neural tumours of the neck presenting as thyroid nodules: a report of three cases

Neural tumours of the neck may at times secondarily involve the thyroid and manifest clinically as thyroid nodules. On cytological evaluation these nodules may be confused with other spindle lesions of the thyroid. We report two cases of schwannoma and one case of a malignant peripheral nerve sheath tumour (MPNST) of the neck, which presented as thyroid nodules and evaluate the role of cytology in identifying these tumours.

The thyroid nodules in all the three cases were sampled by the non-aspiration technique using a 23-gauge needle. Both alcohol-fixed and air-dried smears were prepared and stained by the Papanicolaou and May-Grünwald-Giemsa stains. Cytology smears and histology sections from the resected specimens were reviewed, and the findings noted.

Both the cases of schwannoma were correctly identified on cytology while the case of MPNST could only be typed as a spindle cell tumour. However, on cytology it was not possible to state whether the tumours were thyroidal or extrathyroidal in origin.

Schwannomas of the neck are easily identifiable on cytology compared with MPNST. However, cytology alone is not helpful in identifying the origin of these tumours. As primary neural tumours of the thyroid are rare, the possibility of a soft tissue neural tumour extending into the thyroid should always be ruled out while evaluating these cases.