P2088 - A Rare Case of Paraneoplastic Hypercalcemia Associated With Colorectal Adenocarcinoma

Blace Haviland, DO¹, Dylan Nunn, MS², Emily Franks, MD^3
1Kettering Health, Huber Heights, OH; ²Heritage College of Osteopathic Medicine, Ohio University, Dayton, OH; ³Kettering Health, Kettering, OH

Introduction: Hypercalcemia of malignancy (HCM) is a known complication of malignancy, but is only rarely associated with colorectal cancer. The lowest incidences of HCM have been reported in colorectal and prostate cancers. Malignancy is usually evident clinically by the time hypercalcemia develops, and the finding of such is a poor prognostic factor. We present a case of adenocarcinoma of unknown primary—later discovered to be advanced colorectal adenocarcinoma primarily presenting with symptoms of hypercalcemia —and highlight the rarity of its occurrence.

Case Description/Methods: A 67-year-old male presented with worsening malaise, fatigue, and urinary frequency. He had a recent admission for similar symptoms and was found to have hypercalcemia, transaminitis, hyperbilirubinemia, and a new large pulmonary mass with extensive hepatic metastases on computed tomography (CT). Laboratory evaluation demonstrated worsening of these previous findings as well as an elevated parathyroid hormone-related protein (PTHrP). Immunohistochemical staining (IHC) performed on liver biopsy during the previous admission revealed the metastatic lesions were CDK20 and CDX-2 positive and TTF, CK7 and NKX3 negative. These findings favor colorectal adenocarcinoma over other common cancers in this patient’s demographic group, including lung and prostate cancers. The patient was unfortunately deemed a poor candidate for treatment due to advanced staging and symptoms and was therefore transitioned to hospice.

Discussion: Humoral hypercalcemia of malignancy, characterized by PTHrP induced hypercalcemia, is the primary mechanism of HCM, accounting for 80% of cases. However, this is most commonly associated with squamous cell carcinoma. Colorectal adenocarcinoma is the least common malignancy to cause hypercalcemia. Hypercalcemia can range from mild to severe with symptoms such as fatigue, polyuria, and altered mental status, all of which were observed in our patient. Management is aimed at fluid resuscitation as well as medical management with bisphosphonates and calcitonin. Adenocarcinoma of unknown primary should be investigated with a thorough history and physical, pertinent laboratory evaluation and imaging. Biopsy of the most accessible site should be performed with IHC. Metastatic colon cancer with hypercalcemia carries a poor prognosis. It is important to assess the patient’s fitness, functional status, and medical comorbidities when determining appropriate management.



Disclosures:


Blace Haviland, DO¹, Dylan Nunn, MS², Emily Franks, MD³. P2088 - A Rare Case of Paraneoplastic Hypercalcemia Associated With Colorectal Adenocarcinoma, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.