Parathyroid carcinoma: an analysis of 10 consecutive patients treated in the Hospital of LUHS Kauno Klinikos

Objective Parathyroid carcinoma (PC) is considered a rare malignancy which accounts for less than 1% of hyperparathyroidism cases in reported literature. In B. C. James study there were only 348 cases of PC reported in SEER database 2000-2012, which compose 0,36 (per 1 million) incidence rate. PC occurrence is equal in men and women, while benign parathyroid diseases incidence is higher in women with ratio 3-4:1. Diagnostic criteria were established in 1973 by A. Schantz and B. Castleman which include thick fibrous bands, mitotic activity, vascular and capsular invasion in pathomorphological tests. The variations and pathognomic features are debated as there have been reported large series of patients with metastatic tumours of which as many as 50% were initially misdiagnosed as benign tumours, therefore preoperative diagnosis and staging is often incorrect or not available. Imaging techniques such as sestamibi scintigraphy and neck ultrasound are only used in localizing the parathyroid tissue preoperatively and >3cm size mass may raise suspicion of PC as denoted in Cetani study, however these techniques are in no way diagnostic of PC. This lead to diagnostic markers application such as Ki-67, Cyclin D1, which are more specific to PC than parathyroid adenoma. The course of disease is indolent and most deaths occur due to untreated complications of hypercalcemia. Ten cases of PC were treated in our hospital during the period of 17 years. This review focuses on our experience with the diagnosis, treatment and survival of the patients. Our aim was to review the demographics, diagnostics, treatment and outcomes of the patients, who were surgically treated for parathyroid carcinoma in the Hospital of Lithuanian University of Health Sciences Kauno Klinikos. As large part of contemporary literature on the topic is referencing the older studies from the year 2000 and before, we think that a more recent standpoint can contribute to better understanding the PC. Methods The model of the study was retrospective. Data on demographics, initial symptoms, preoperative diagnostic blood tests and instrumental procedures, surgical operations, complications, postoperative blood tests, and histology of tumours was collected. The data concerning patients‘ survival was acquired from the Lithuanian National Cancer Institute’s Cancer Registry. Results There were 10 patients who were treated surgically for parathyroid carcinoma. During the study period patients with PC accounted for 2,2 percent of all the patients with parathyroid gland pathology treated surgically in our clinic. Among PC patients there were 7 females, age distribution was from 54 – 74, mean – 64 years. Eighty percent of admitted patients suffered from complications. The most prevalent symptoms were renal function impairment, nephrolithiasis and subsequent pyelonephritis. Three patients had suffered from spontaneous bone fractures. Other common complaints included joint pain and malaise, hoarseness of voice.. Five patients had palpable disease at time of admission. One patient was asymptomatic (Table 1). Preoperative blood tests showed increased serum calcium 2,62-3,4 mmol/l (normal range (NR) – 2,15-2,55 mmol/l), ionized calcium 1,15- 1,57 mmol/l (NR – 0,98-1,13 mmol/l), and PTH 23,91 – 210 pmol/l (NR – 1,2-5,3 pmol/l), which plunged to normal range after surgical treatment. All patients were tested with ultrasound and scintigraphy. Five fine needle aspirational (FNA) punctures of nodules were performed (Table 3). None of the tests were diagnostic of parathyroid carcinoma preoperatively, nevertheless 5 out of 5 cytology showed features of malignancy. En-bloc parathyroidectomies were performed on all patients with various extents of thyroid gland removal. The diagnoses of PC were confirmed with histologic tests. Most prevalent features included vascular invasion (70%), capsular invasion (60%) and presence of fibrous bands (60%). There were no cases with distant metastases at initial surgery and lymphonodectomies were not performed. Data from Cancer registry showed, that 8 out of 10 patients were alive (survivability ranging from 4 months to 16 years postoperatively). Two of the patients have deceased due to carcinoma of pancreas and thyroid gland 2 and 4 years respectively after the operation. Conclusions Parathyroid carcinoma has complex diagnostics and staging because of its rarity and lack of studies. Majority of PC patients present with hypercalcemia and its complications – renal insufficiency, nephrolithiasis. Palpable neck mass is prevalent in half of the patients. Lesser than 3,5 mmol/l values of serum calcium should not lessen the suspicion of PC. The outcome of non-metastasized PC is favourable when en-bloc resection of the tumour is performed. Brief description of the abstract Objective: Review the diagnostics, treatment and outcomes of the patients, who were surgically treated for parathyroid carcinoma in the Hospital of LUHS Kauno klinikos from 2003 to 2019. Conclusions: Majority of PC patients present with hypercalcemia and its complications – renal insufficiency, nephrolithiasis. Lesser than 3,5 mmol/l values of serum calcium should not lessen the suspicion of PC. The outcome of non-metastasized PC is favourable when en-bloc resection of the tumour is performed.