ENDOMETRIOSIS-TRANSFORMED UTERINE CLEAR CELL CARCINOMA WITH ASYMPTOMATIC PTHrP MEDIATED HYPERCALCEMIA

INTRODUCTION/BACKGROUNDHypercalcemia is a well-recognized complication of various solid tumours and hematologic malignancies. Clear cell carcinoma arising from the malignant transformation of endometriosis is a rare and typically aggressive cancer which occasionally presents only with hypercalcemia. In this report, we describe a case of parathyroid hormonerelated protein (PTHrP) hypercalcemia secondary to endometrial clear cell carcinoma including the results of biochemical laboratory tests and discuss treatment strategies with related literature reviews. CASEA 50-year-old female with endometriosis was incidentally found to have mild hypercalcemia during hospitalization for SAR COV (COVID-19) infection. Parathyroid hormone (iPTH) was suppressed, while PTHrP was significantly elevated at 30 pmol/L (<1.3 pmol/L). A comprehensive investigation for malignancy was done, which revealed no abnormalities except for the progressive enlargement of her underlying endometriosis. An extended hysterectomy was performed, and subsequent histological examination confirmed the presence of endometrial clear cell carcinoma. Post-surgery, her serum calcium level went back to normal levels. CONCLUSIONThis is a case of uterine clear cell carcinoma arising from endometriosis complicated with hypercalcemia and highlights that hypercalcemia may be the sole sign of disease transformation, despite the well-established aggressive nature of the disease. It is then crucial to perform a timely and thorough assessment, followed by appropriate management