A case report of parathyroid hyperplasia diagnosed by DPP IV activity staining

Background: Aspiration biopsy cytology (ABC) is rarely perfomed on the parathyroid gland itself. However, in cases of differential diagnosis to determine a thyroid or parathyroid origin, ABC and enzyme-cytochemistry of dipeptidyl peptidase IV (DPP IV) are extremely useful. Case: A 49-year-old Japanese male had a history of hemodialysis due to chronic renal failure for 15 years. For the last three years, he occasionally complained of lumbago, and the serum level of parathyroid hormone was gradually elevated. An ultrasonographic study revealed two masses in the neck region; one was located at the dorsal side of the lower pole of the left thyroid gland, and the other was adjacent to the lower pole of the right thyroid gland. ABC was performed on these masses, and revealed small and uniform cells in sheets without nuclear grooves and pseudo-inclusion bodies in routine Papanicolaou staining. In order to clarify their origin, enzyme cytochemistry and immunocytochemistry were also performed. The cells were strongly positive for DPPIV and parathyroid hormone but not for thyroglobulin, indicating that these cells originated from parathyroid glands. Surgically, the masses were actually swollen parathyroid glands partly attached to the thyroid glands. Histological examination showed a proliferation of chief cells in trabecular or sheeting fashion. The final pathological diagnosis was secondary hyperplasia of parathyroid glands. Conclusion: In this case, enzyme cytochemistry of DPP IV has helpful diagnostic value for differential diagnosis between hyperplasia of the parathyroid gland and non-papillary tumor of the thyroid gland.