Case Presentation:
A 61 year old female with history of metastatic breast carcinoma presented to the hospital for an elective vertebral cryoablation and kyphoplasty to treat her painful bony metastasis. She has known vertebral lytic lesions in addition to a suspected right adrenal involvement. On the first day, cryoablation was performed uneventfully under general anesthesia. Post operatively, however, she had an unexplained transient hypotensive episode with a systolic blood pressure down to 85 mmHg from a normal baseline. On the following day, she underwent general anesthesia for kyphoplasty. Right after the initiation of the procedure, her systolic blood pressure increased to a level of 230 mmHg. The procedure was aborted and she was admitted to a telemetry unit. One dose of IV labetalol was given and her blood pressure normalized within 2 hours. Work up was initiated for her labile blood pressure. The patient had no fever, her pain was controlled with medications, and she was euvolemic on physical examination. Upon further inquiry, the patient recalled several previous episodes of transient hypertension (as high as 250/110) and headache after chemotherapy infusion. Her baseline blood pressure was otherwise normal, and she had not been on any antihypertensive medications. A careful review of her previous abdominal CT scan revealed a 3-cm right adrenal heterogeneous nodule which was thought to represent a metastatic lesion from her breast carcinoma. Biochemical evaluation, including plasma normetanephrines and 24-hour urine metanephrines, was done. This confirmed the suspicion of pheochromocytoma.
Discussion:
Although unusual, patients with one known malignancy can develop another synchronous neoplasm. Concomitant presentation of metastatic breast cancer and pheochromocytoma is rare and has been described in one other case report.
Up to 40 % of patients with metastatic breast cancer have adrenal gland involvement. On the other hand, only 3% of patients with adrenal incidentaloma on imaging have pheochromocytoma. The diagnosis of pheochromocytoma is further challenged by the fact that routine unenhanced CT, which is helpful for ruling in non-functional adrenal adenoma when the density is low (Hounsfield unit <10), does not distinguish metastasis from functional adrenal tumors, as they both have high density (Hounsfield unit > 20). Therefore, obtaining relevant history in addition to biochemical evaluation in both urine and serum collections is key to unmasking the diagnosis.
Adrenalectomy is the definitive treatment. Importantly, patients with pheochromocytoma must receive alpha blockade followed by beta-blockade prior to the surgery, to prevent perioperative hypertensive crisis.
Conclusions:
Functional adrenal tumor should remain in the differential for patients with metastatic malignancy and suspected adrenal involvement. Careful history and biochemical evaluation are key elements in making the diagnosis and avoiding perioperative catastrophes.