A Case of Intrathyroidal Parathyroid Carcinoma Accompanied by Contralateral Parathyroid Hyperplasia

Parathyroid carcinoma accounts for about 0.5%-5% of all parathyroid neoplasms. Very rarely, but if the intrathyroidal parathyroid gland is present, the carcinoma can arise in that developmental anomaly. It is very difficult to distinguish a thyroid nodule from an intrathyroidal parathyroid neoplasm with preoperative radiologic and cytologic evaluations. A 59-year-old male was initially evaluated as presenting a follicular thyroid neoplasm accompanied by hyperparathyroidism. He received hemi-thyroidectomy with central neck dissection and subtotal parathyroidectomy. The final pathology evaluation revealed intrathyroidal parathyroid carcinoma and hyperplasia of contralateral parathyroid glands. We report this very rare and unique clinical situation with a literature review.

663 Metastatic Parathyroid Cancer with Refractory Hypercalcaemia

A 45-year-old gentleman presented to hospital with vomiting. Bloods demonstrated a corrected calcium of 4.48 and PTH of 979. CT neck showed a right sided thyroid lesion, which on FNA was reported as a possible thyroid or parathyroid neoplasm. A NM scan showed an enhancing nodule in the right thyroid gland and lytic vertebral and pelvic lesions. Bone biopsy showed parathyroid carcinoma. He underwent palliative total thyroidectomy and right superior and inferior parathyroidectomy under the ENT team. His thyroidectomy specimen was reported as right inferior parathyroid carcinoma, infiltrating into the thyroid gland. His calcium levels did not normalise post-surgery and corrected levels were consistently above 3, with PTH > 5000 despite fluid and calcimimetic therapy with only temporary normalisation with bisphosphonates and denosumab. This refractory hypercalcaemia is due to the bony metastases producing PTH, which represents a primary cause of mortality. He is currently being managed with regular fluid infusions and bisphosphonates, with view to commence palliative chemotherapy. Parathyroid carcinoma is extremely rare, and rarer still to present with metastatic disease. Treatment options are limited, with poor evidence behind chemoradiation and immunotherapy. Clinicians should be aware of the complications and management of refractory hypercalcaemia linked to this disease entity.

Ectopic Atypical Parathyroid Adenoma Presenting With Pancreatitis

Background: Atypical Parathyroid Adenoma (APA) and parathyroid carcinomas (PC) are rare parathyroid tumors (<1%) causing primary hyperparathyroidism. We present a case of ectopic APA in the left anterior mediastinum. Case: A 38 year old male with hyperlipidemia admitted for acute pancreatitis noted to have calcium level of 13.4 mg/dl (8.6–10.3mg/dl) in the absence of family history of hypercalcemia or kidney stones. He was treated with zoledronic acid, intravenous fluids and calcitonin for hypercalcemia. Pancreatitis resolved with fluid management. Calcium on discharge was 9.9 mg/dl. 8 week follow-up labs showed PTH of 420 pg/ml (14–64 pg/ml), calcium 10.2 mg/dl, phosphorus 1.9 mg/dl (2.5–4.5 mg/dl), vitamin D 19 ng/ml (30–100 ng/ml), 24-hour urinary calcium 115 mg/24 hour (55–300 mg/24 hour) and calcium to creatinine ratio 0.41. Hence diagnosis of primary hyperparathyroidism was made but given the degree of calcium and PTH elevation there was a concern for PC. Ultrasound of the neck demonstrated no abnormality. Sestamibi scan showed irregular focal accumulation of radiotracer in the left upper mediastinum suggestive of mediastinal ectopic parathyroid adenoma (EPA). CT chest with contrast showed a 3.9 x 2.2 x 3.4cm lobulated, heterogenous, hypodense, minimally enhancing mass in the left anterior prevascular space. Diagnosis of EPA was made and he underwent left video assisted thoracic surgery. Operative findings showed a multilobular mass at the level of the aortic arch between vagus and phrenic nerves. Intraoperative PTH went from 1124 pg/ml pre-incision to 160 at 15-minute post-excision. Postoperative calcium was 9.6 mg/dl and PTH 51 pg/ml. Final pathology showed 3.7 x 2.5 x 2cm, hypercellular parathyroid with prominent fibrous band and parafibromin retention compatible with APA. Discussion: APA is an intermediate form of parathyroid neoplasm with uncertain malignant potential, showing atypical histological features without evidence of invasive growth. This poses a diagnostic challenge of PC as the histopathological features overlap and requires an expert pathologist to make the diagnosis. Inactivating CDC73 mutations, encoding parafibromin, is the most common genetic abnormality. Loss of parafibromin has been seen in 100% cases of PC and predicts poor prognosis. Due to rarity of the disease there are no clear guidelines on follow up. Based on literature, annual follow up is suggested with biochemical testing and imaging for the first 5 years after surgery and every 2–3 years thereafter due to 3% recurrence rate and potential progression to PC. Cetani et al in 2019 reported 672 cases of APA, only 3 were ectopic in the mediastinum thus making our case rare. APA is a rare entity as biochemical profile and histopathological features overlap with PC and can be misdiagnosed. Greater awareness of APA may improve capture of cases, allowing the development of guidelines to recognize and treat it.

A Case of Parathyroid Adenocarcinoma and Hyperparathyroidism, When “CRAB” Symptoms Are Not due to a Plasma Cell Myeloma

A previously well 49-year-old patient presented to our hospital with symptomatic hypercalcaemia complaining of polyuria and polydipsia, as well as abdominal and lower back pain (serum/ionized calcium at 3.66 milli mole/l and 1.90 milli moles/l). At admission, he had a normocytic anemia (Hb, 99 g/L) and acute kidney injury (creatinine at 161 μM). His parathyroid hormone (PTH) levels were at 67.6 pico moles/l. A plain X-ray of the lumbar spine showed the presence of a lytic lesion in the L4 vertebrae. CT and MRI confirmed this to be a destructive lesion. A subsequent pan CT scan showed a 2.8 cm complex nodule in the left lobe of the thyroid posteriorly. Excisional biopsy of the resected mass was associated with an infiltrative cellular parathyroid neoplasm with solid and nested architectural growth pattern admixed with hemorrhage and focal calcifications. The tumor showed lymphovascular and perineural invasion. At the time of workup and despite the absence of a positive SPEP/UPEP, a bone marrow biopsy was requested to rule out multiple myeloma. His normocellular bone marrow biopsy showed marked paratrabecular fibrosis and extensive bony remodelling but no metastatic invasion. The diagnosis of a metastatic parathyroid carcinoma was made. He is subsequently considered for palliative radiotherapy to the primary tumor bed and the lumbar spine. In addition, a role for immunotherapy with ipilimumab and nivolumab in context of clinical trials is envisioned and he is being considered for enrollment.

Atypical presentation of oncocytic parathyroid adenoma masquerading as metastatic carcinoma

Parathyroid carcinoma is the rarest endocrine malignancy. Definitive diagnosis is challenging as it is difficult to distinguish malignant from benign disease. A 71-year-old man presented with weight loss and hypercalcaemia. CT scans revealed multiple lung nodules and lytic bone lesions that were consistent with metastatic dissemination. Technetium-99m-sestamibi-single-photon emission computed tomography scan showed an abnormal uptake in the right thyroid lobe. Fine-needle aspiration (FNA) was performed on three occasions. The patient underwent parathyroidectomy with ipsilateral hemithyroidectomy without postoperative complications. Microscopic examination showed a parathyroid neoplasm with fibrosis and intravascular tumour on a background of unremarkable thyroid parenchyma. This resulted in an initial impression of parathyroid carcinoma. Further review by two independent pathologists provided a final diagnosis of oncocytic parathyroid adenoma. This case highlights the subjectivity and interobserver variation with endocrine histological examination. FNA can induce changes that mimic parathyroid carcinoma on histology. An index of suspicion for benign parathyroid adenomas should be maintained.

A Case Report on Parathyroid Carcinoma: A Diagnostic Dilemma

Parathyroid Carcinoma is a rare cause of primary hyperparathyroidism. Pre-operative diagnosis remains a challenge. Here we report a case referred to us for suspicious goiter with hypercalcemia. Cytological findings suggested it to a possible thyroid mass rather than parathyroid neoplasm. Serum parathormone level was high and the patient underwent surgery. Histopathology confirmed the diagnosis of parathyroid carcinoma. A diagnostic approach to parathyroid neoplasm, combining multimodality imaging and clinico-pathologic features, is discussed. Bangladesh J. Nuclear Med. 21(2): 122-124, July 2018

Cytomorphologic features distinguishing Bethesda category IV thyroid lesions from parathyroid

Background: Thyroid follicular cells share similar cytomorphological features with parathyroid. Without a clinical suspicion, the distinction between a thyroid neoplasm and an intrathyroidal parathyroid can be challenging. The aim of this study was to assess the distinguishing cytomorphological features of parathyroid (including intrathyroidal) and Bethesda category IV (Beth-IV) thyroid follicular lesions, which carry a 15%–30% risk of malignancy and are often followed up with surgical resection. Methods: A search was performed to identify “parathyroid” diagnoses in parathyroid/thyroid-designated fine-needle aspirations (FNAs) and Beth-IV thyroid FNAs (follicular and Hurthle cell), all with diagnostic confirmation through surgical pathology, immunocytochemical stains, Afirma® analysis, and/or clinical correlation. Unique cytomorphologic features were scored (0-3) or noted as present versus absent. Statistical analysis was performed using R 3.3.1 software. Results: We identified five FNA cases with clinical suspicion of parathyroid neoplasm, hyperthyroidism, or thyroid lesion that had an eventual final diagnosis of the parathyroid lesion (all female; age 20–69 years) and 12 Beth-IV diagnoses (11 female, 1 male; age 13–64 years). The following cytomorphologic features are useful distinguishing features (P value): overall pattern (0.001), single cells (0.001), cell size compared to red blood cell (0.01), nuclear irregularity (0.001), presence of nucleoli (0.001), nuclear-to-cytoplasmic ratio (0.007), and nuclear chromatin quality (0.028). Conclusions: There are cytomorphologic features that distinguish Beth-IV thyroid lesions and (intrathyroidal) parathyroid. These features can aid in rendering correct diagnoses and appropriate management.