Paraneoplastic renal tubular acidosis secondary to ovarian teratoma

Background: Renal tubular acidosis (RTA) is a relatively uncommon disorder, often linked to autoimmune conditions or adverse effects of certain medications. It is rare for clinicians to encounter this disorder during their medical practice. There are 3 distinct types: type 1(distal), type 2 (proximal), and type 4 (hypoaldosteronism). Etiology of a specific case of RTA can be difficult to pin, which is what prompted us to get further imaging. Our case report is going to reveal a rare relationship between RTA and an ovarian teratoma. Ovarian teratomas are a type of germ cell tumor that are composed of somatic tissue, typically ectoderm, endoderm, and mesoderm. These tissues are foreign to the anatomic site they are found in. More than 95% of ovarian teratomas are mature cystic teratomas which are generally asymptomatic. If symptoms do occur, they are typically associated with the size of the teratoma itself.

Case Presentation: This case begins with a female patient presenting to the emergency department with acute paralysis of all four of her extremities. Initial laboratory results revealed a potassium value of 1.5mEq/L. Consistent with this hypokalemia, EKG changes showed distinct U-waves. This patient was promptly treated with aggressive potassium repletion. Interestingly, the potassium failed to rise as expected, so focuses on potassium loss were explored. A comprehensive work-up ultimately led to a working diagnosis of renal tubular acidosis (RTA). A CT scan of the abdomen revealed a large ovarian teratoma. Interestingly, this patient had a history of a similar mass previously which was resected successfully in the past. Surgical removal of the teratoma was indicated, and after the procedure, her potassium was normalized appropriately. This raised an intriguing question: 'Could this teratoma be the source of her hypokalemia?’ Her paralysis corrected as her potassium was replenished, and she was able to safely discharge from the hospital with oral potassium supplementation and close follow-up. At subsequent follow-ups, her potassium did remain within normal limits with intermittent lowering that was far less severe than her initial presentation.

Discussion: This case report aims to highlight a rare presentation of severe symptomatic hypokalemia potentially linked to an ovarian teratoma with underlying autoimmune or paraneoplastic factors. The concurrence of RTA and ovarian teratomas are exceedingly rare within scientific literature. With the presentation of this case, we emphasize the potential value of exploring paraneoplastic syndromes associated with ovarian teratomas and subsequent clinical implications.