An unusual ectopic location of a parathyroid carcinoma arising within the thyroid gland.

INTRODUCTION: Parathyroid carcinomas are very rare tumors and may arise in the normally located or ectopic gland. The latter present certain diagnostic difficulties, and there are no specific guidelines on their management. We present a case of parathyroid carcinoma arising within an ectopically located intrathyroid gland and discuss the diagnosis, management, and difficulties encountered. Furthermore, we review all six previously reported cases of this rare event and demonstrate the patterns in presentation, as well as the differences in management.

CASE PRESENTATION: A 39-yr-old male presented with a right neck mass with biochemical derangement suggestive of a parathyroid lesion. However, radiological investigations were inconclusive as to the true nature of this lesion because they demonstrated a mass within the right thyroid lobe. A sestamibi (99m)technetium subtraction study was performed, which suggested an intrathyroid parathyroid carcinoma. The patient underwent successful surgical intervention.

CONCLUSION: Although rare, ectopically located parathyroid glands can harbor malignant disease. Those located within the thyroid gland can be difficult to diagnose, and thus a combination of radiological modalities, including sestamibi (99m)technetium studies, need to be utilized. Although surgical resection is the most effective treatment, there are no specific guidelines as to the radicality of such treatment.