A Case of Parathyroid Carcinoma in Renal Hyperparathyroidism

Introduction

Parathyroid carcinoma is a rare malignant endocrine tumor that is usually associated with primary hyperparathyroidism. The coexistence of parathyroid carcinoma and renal hyperparathyroidism is a rare phenomenon. Hence, we present a case of parathyroid carcinoma in a patient with tertiary hyperparathyroidism.

Case Presentation

Our patient is a 31-year-old woman with a past medical history of end-stage renal failure (ESRF), on hemodialysis for the past 18 years. She was referred by her nephrologist to the endocrine surgery department for consideration of parathyroidectomy in view of long-standing tertiary hyperparathyroidism complicated by hypercalcemia. Bedside ultrasonography scan (US) of the thyroid revealed three parathyroid glands and a hypoechoic right lower pole thyroid nodule with central calcification. Fine-needle aspiration cytology was performed for the suspected thyroid nodule on the same day, which eventually yielded a follicular lesion of undetermined significance. A right hemithyroidectomy and total parathyroidectomy with deltoid implantation was performed. Intraoperative exploration revealed that the thyroid nodule noted at initial US was found to be the right superior parathyroid gland invading into the right thyroid itself. The right superior parathyroid gland was excised en bloc with the right hemithyroidectomy. Post-operatively, the patient was hypocalcemic but was discharged well on post-operative day 5. Histopathological diagnosis of the right hemithyroidectomy specimen containing the right superior parathyroid gland was consistent with that of parathyroid carcinoma.

Conclusion

Parathyroid carcinoma is a rare entity that is difficult to diagnose. In patients with ESRF, the presence of concurrent tertiary hyperparathyroidism makes this even more challenging.

COVID-19 post-vaccination lymphadenopathy: Report of cytological findings from fine needle aspiration biopsy

The coronavirus COVID-19 pandemic has spurred the rapid development of vaccines, with vaccination programmes already underway in many countries. Regional lymphadenopathy is one of the documented side effects of vaccination. We document the fine needle aspiration cytological findings of an enlarged supraclavicular lymph node in a 34-year-old Asian female following the first dose of the Pfizer-BioNTech COVID-19 mRNA vaccine, which appears to be the first such report in a premorbidly well patient with no known history of malignancy. The cytological findings featured a reactive pattern in keeping with follicular hyperplasia, with prominent germinal centre elements including lymphohistiocytic aggregates and tingible-body macrophages. Despite an increased proportion of larger lymphocytes, the overall pattern was in keeping with a reactive pattern, bearing in mind the temporal and geographic relation to the vaccination injection. In instances of localised lymphadenopathy, particularly in supraclavicular or axillary locations, pathologists should be cognizant of the possibility of post-vaccination reactive lymphadenopathy, and seek clinical and radiological hints favouring a benign process, whilst recognising potential morphological overlaps with lymphoproliferative disorders. Awareness of this diagnostic pitfall is especially important as COVID-19 vaccination coverage is ramped up worldwide, leading to an expected increase in incidence of post-vaccination reactive lymphadenopathy.

YJ5 as an immunohistochemical marker of osteogenic lineage

Overexpression of WLS, an upstream protein in the Wnt pathway, has been implicated in several non-osteogenic tumours. This study represents the first attempt at evaluating WLS expression in various bone and soft tissue tumours using YJ5, a monoclonal antibody specific to WLS, with the aim of elucidating its utility in discerning tumours with aberrant Wnt signalling and as a marker of osteogenic lineage in challenging cases. Tumour tissue sections of 144 bone mass lesions and 63 soft tissue mass lesions were immunostained with the YJ5 antibody following standardised protocols. Subsequent assessment of immunoreactivity segregated cases into one of three groups: absent/weak, moderate, or strong YJ5 immunoreactivity. For the bone tumours, strong YJ5 immunoreactivity was seen in almost all osteosarcomas and chondroblastomas, all osteoblastomas and osteoid osteomas. In contrast, all other cartilaginous tumours, chordomas, aneurysmal bone cysts, chondromyxoid fibromas, most fibrous dysplasias and most giant cell tumours exhibited absent/weak YJ5 immunostaining. For the soft tissue tumours, a more heterogeneous pattern of YJ5 immunoreactivity was observed. Because diffuse and strong YJ5 expression is identified in almost all benign and malignant bone tumours with osteoblastic activity, it can be potentially utilised as an immunohistochemical marker to support osteogenic lineage. If interpreted in the appropriate context, this marker is useful in determining whether a malignant bone tumour is an osteosarcoma, particularly in those subtypes with no or minimal osteoid or unusual morphological features. This marker can also complement SATB2 to denote osteogenic lineage.