Case Report: Refractory Hyponatremia in Malignant Melanoma

Orlando—There were approximately 76,000 new cases of malignant melanoma in the United States and 10,000 melanoma-related deaths in 2016. Some patients with malignant melanoma develop fungating wounds that are associated with significant patient distress and morbidity.

Rui Mao, MD, and colleagues presented a case report on a 43-year-old man who developed malignant melanoma on his back with metastases to his left supraclavicular lymph nodes. The case report was presented during a poster session at the NKF 2017 Spring Clinical Meetings in a poster titled Refractory Hyponatremia in a Patient with Fungating Metastatic Melanoma.

The lesion on the patient’s back was treated with wide local excision, radiation, and combination trametinib and dabrafenib therapy. Despite chemotherapy and CyberKnife therapy, the patient’s disease had progressed and he required admission to the hospital for relief of pain and the tumor burden.

At admission, the patient had a football-sized, fungating tumor on his left shoulder, with extensive loss of fluid and bleeding. Results of laboratory tests revealed severe hyponatremia of 113 mEq/L. Additional laboratory workups showed persistently low urine sodium <10 mEq/L and urine osmolality of 834 mOsm/kg. Multiple transfusions were administered, along with continuous normal saline at a rate of 300 mL per hour; however, the hyponatremia persisted.

In light of reports of secondary adrenal insufficiency from hypopituitarism associated with dabrafenib, the patient was empirically treated with hydrocortisone, resulting in some improvement in the hyponatremia. However, in order to improve his serum sodium to 130 mEq/L, continued IV fluids were required because of extensive fluid losses from the tumor. Ultimately, the patient underwent palliative amputation of his left upper extremity to control fluid losses.

In summary, the researchers said, “This is a rare case of refractory hyponatremia due to extensive fluid losses from locally advanced malignant melanoma as well as chemotherapy with dabrafenib. It is important to consider adrenal insufficiency in melanoma patients on dabrafenib as complete treatment involves initiation of steroids and cessation of the offending agent.”

Source: Mao R, Tran TP, Baradhi K. Refractory hyponatremia in a patient with fungating metastatic melanoma. Abstract of a poster presented at the National Kidney Foundation 2017 Spring Clinical Meetings, April 19-22, 2017, Orlando, Florida.